kubernetes
/
git-sync
mirror of https://github.com/kubernetes/git-sync.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Clean up logging using glogr

This commit is contained in:
Tim Hockin 2016-08-24 21:27:15 -07:00
parent ff73d8e4f0
commit dd60fb0312
14 changed files with 2201 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
Godeps/Godeps.json generated Normal file
View File

@ -0,0 +1,22 @@
{
"ImportPath": "k8s.io/git-sync",
"GoVersion": "go1.6",
"GodepVersion": "v66",
"Packages": [
"./..."
],
"Deps": [
{
"ImportPath": "github.com/golang/glog",
"Rev": "23def4e6c14b4da8ac2ed8007337bc5eb5007998"
},
{
"ImportPath": "github.com/thockin/glogr",
"Rev": "7a7f3ced4f9f52e96710761820bd85ed6c400aa5"
},
{
"ImportPath": "github.com/thockin/logr",
"Rev": "103d90809f342ce8b186c0bc903a34bc1c8007be"
}
]
}

5
Godeps/Readme generated Normal file
View File

@ -0,0 +1,5 @@
This directory tree is generated automatically by godep.
Please do not edit.
See https://github.com/tools/godep for more information.

5
Makefile
View File

@ -32,7 +32,6 @@ KUBE_CROSS_VERSION ?= v1.6.3-2
GO_PKG = k8s.io/git-sync GO_PKG = k8s.io/git-sync
BIN = git-sync BIN = git-sync
SRCS = main.go
# If you want to build all containers, see the 'all-container' rule. # If you want to build all containers, see the 'all-container' rule.
# If you want to build AND push all containers, see the 'all-push' rule. # If you want to build AND push all containers, see the 'all-push' rule.
@ -52,7 +51,7 @@ all-push: $(addprefix sub-push-,$(ALL_ARCH))
build: bin/$(BIN)-$(ARCH) build: bin/$(BIN)-$(ARCH)
bin/$(BIN)-$(ARCH): $(SRCS) bin/$(BIN)-$(ARCH): FORCE
mkdir -p bin mkdir -p bin
docker run \ docker run \
-u $$(id -u):$$(id -g) \ -u $$(id -u):$$(id -g) \
@ -87,3 +86,5 @@ endif
clean: clean:
rm -rf .container-* .push-* bin/ rm -rf .container-* .push-* bin/
FORCE:

82
main.go
View File

@ -24,7 +24,6 @@ import (
"fmt" "fmt"
"io" "io"
"io/ioutil" "io/ioutil"
"log"
"os" "os"
"os/exec" "os/exec"
"os/signal" "os/signal"
@ -33,6 +32,9 @@ import (
"strconv" "strconv"
"strings" "strings"
"time" "time"
"github.com/thockin/glogr"
"github.com/thockin/logr"
) )
var flRepo = flag.String("repo", envString("GIT_SYNC_REPO", ""), "git repo url") var flRepo = flag.String("repo", envString("GIT_SYNC_REPO", ""), "git repo url")
@ -59,6 +61,17 @@ var flPassword = flag.String("password", envString("GIT_SYNC_PASSWORD", ""), "pa
var flSSH = flag.Bool("ssh", envBool("GIT_SYNC_SSH", false), "use SSH protocol") var flSSH = flag.Bool("ssh", envBool("GIT_SYNC_SSH", false), "use SSH protocol")
var log = newLoggerOrDie()
func newLoggerOrDie() logr.Logger {
g, err := glogr.New()
if err != nil {
fmt.Fprintf(os.Stderr, "failind to initialize logging: %v", err)
os.Exit(1)
}
return g
}
func envString(key, def string) string { func envString(key, def string) string {
if env := os.Getenv(key); env != "" { if env := os.Getenv(key); env != "" {
return env return env
@ -82,7 +95,7 @@ func envInt(key string, def int) int {
if env := os.Getenv(key); env != "" { if env := os.Getenv(key); env != "" {
val, err := strconv.Atoi(env) val, err := strconv.Atoi(env)
if err != nil { if err != nil {
log.Printf("invalid value for %q: using default: %q", key, def) log.Errorf("invalid value for %q: using default: %q", key, def)
return def return def
} }
return val return val
@ -90,29 +103,29 @@ func envInt(key string, def int) int {
return def return def
} }
const usage = "usage: GIT_SYNC_REPO= GIT_SYNC_DEST= [GIT_SYNC_BRANCH= GIT_SYNC_WAIT= GIT_SYNC_DEPTH= GIT_SYNC_USERNAME= GIT_SYNC_PASSWORD= GIT_SYNC_SSH= GIT_SYNC_ONE_TIME= GIT_SYNC_MAX_SYNC_FAILURES=] git-sync -repo GIT_REPO_URL -dest PATH [-branch -wait -username -password -ssh -depth -one-time -max-sync-failures]"
func main() { func main() {
setFlagDefaults()
flag.Parse() flag.Parse()
if *flRepo == "" || *flDest == "" { if *flRepo == "" || *flDest == "" {
flag.Usage() flag.Usage()
os.Exit(1) os.Exit(1)
} }
if _, err := exec.LookPath("git"); err != nil { if _, err := exec.LookPath("git"); err != nil {
log.Printf("required git executable not found: %v", err) log.Errorf("required git executable not found: %v", err)
os.Exit(1) os.Exit(1)
} }
if *flUsername != "" && *flPassword != "" { if *flUsername != "" && *flPassword != "" {
if err := setupGitAuth(*flUsername, *flPassword, *flRepo); err != nil { if err := setupGitAuth(*flUsername, *flPassword, *flRepo); err != nil {
log.Printf("error creating .netrc file: %v", err) log.Errorf("error creating .netrc file: %v", err)
os.Exit(1) os.Exit(1)
} }
} }
if *flSSH { if *flSSH {
if err := setupGitSSH(); err != nil { if err := setupGitSSH(); err != nil {
log.Printf("error configuring SSH: %v", err) log.Errorf("error configuring SSH: %v", err)
os.Exit(1) os.Exit(1)
} }
} }
@ -122,22 +135,22 @@ func main() {
for { for {
if err := syncRepo(*flRepo, *flBranch, *flRev, *flDepth, *flRoot, *flDest); err != nil { if err := syncRepo(*flRepo, *flBranch, *flRev, *flDepth, *flRoot, *flDest); err != nil {
if initialSync || failCount >= *flMaxSyncFailures { if initialSync || failCount >= *flMaxSyncFailures {
log.Printf("error syncing repo: %v", err) log.Errorf("error syncing repo: %v", err)
os.Exit(1) os.Exit(1)
} }
failCount++ failCount++
log.Printf("unexpected error syncing repo: %v", err) log.Errorf("unexpected error syncing repo: %v", err)
log.Printf("waiting %d seconds before retryng", *flWait) log.V(0).Infof("waiting %d seconds before retryng", *flWait)
time.Sleep(time.Duration(*flWait) * time.Second) time.Sleep(time.Duration(*flWait) * time.Second)
continue continue
} }
if initialSync { if initialSync {
if isHash, err := revIsHash(*flRev, *flRoot); err != nil { if isHash, err := revIsHash(*flRev, *flRoot); err != nil {
log.Printf("can't tell if rev %s is a git hash, exiting", *flRev) log.Errorf("can't tell if rev %s is a git hash, exiting", *flRev)
os.Exit(1) os.Exit(1)
} else if isHash { } else if isHash {
log.Printf("rev %s appears to be a git hash, no further sync needed", *flRev) log.V(0).Infof("rev %s appears to be a git hash, no further sync needed", *flRev)
sleepForever() sleepForever()
} }
if *flOneTime { if *flOneTime {
@ -147,11 +160,21 @@ func main() {
} }
failCount = 0 failCount = 0
log.Printf("next sync in %d seconds", *flWait) log.V(0).Infof("next sync in %d seconds", *flWait)
time.Sleep(time.Duration(*flWait) * time.Second) time.Sleep(time.Duration(*flWait) * time.Second)
} }
} }
func setFlagDefaults() {
// Force logging to stderr.
stderrFlag := flag.Lookup("logtostderr")
if stderrFlag == nil {
fmt.Fprintf(os.Stderr, "can't find flag 'logtostderr'")
os.Exit(1)
}
stderrFlag.Value.Set("true")
}
// Do no work, but don't do something that triggers go's runtime into thinking // Do no work, but don't do something that triggers go's runtime into thinking
// it is deadlocked. // it is deadlocked.
func sleepForever() { func sleepForever() {
@ -179,12 +202,12 @@ func updateSymlink(gitRoot, link, newDir string) error {
if _, err := runCommand(gitRoot, "ln", "-snf", newDirRelative, "tmp-link"); err != nil { if _, err := runCommand(gitRoot, "ln", "-snf", newDirRelative, "tmp-link"); err != nil {
return fmt.Errorf("error creating symlink: %v", err) return fmt.Errorf("error creating symlink: %v", err)
} }
log.Printf("created symlink %s -> %s", "tmp-link", newDirRelative) log.V(1).Infof("created symlink %s -> %s", "tmp-link", newDirRelative)
if _, err := runCommand(gitRoot, "mv", "-T", "tmp-link", link); err != nil { if _, err := runCommand(gitRoot, "mv", "-T", "tmp-link", link); err != nil {
return fmt.Errorf("error replacing symlink: %v", err) return fmt.Errorf("error replacing symlink: %v", err)
} }
log.Printf("renamed symlink %s to %s", "tmp-link", link) log.V(1).Infof("renamed symlink %s to %s", "tmp-link", link)
// Clean up previous worktree // Clean up previous worktree
if len(currentDir) > 0 { if len(currentDir) > 0 {
@ -192,14 +215,14 @@ func updateSymlink(gitRoot, link, newDir string) error {
return fmt.Errorf("error removing directory: %v", err) return fmt.Errorf("error removing directory: %v", err)
} }
log.Printf("removed %s", currentDir) log.V(1).Infof("removed %s", currentDir)
_, err := runCommand(gitRoot, "git", "worktree", "prune") _, err := runCommand(gitRoot, "git", "worktree", "prune")
if err != nil { if err != nil {
return err return err
} }
log.Printf("pruned old worktrees") log.V(1).Infof("pruned old worktrees")
} }
return nil return nil
@ -213,7 +236,6 @@ func addWorktreeAndSwap(gitRoot, dest, branch, rev string) error {
if err != nil { if err != nil {
return err return err
} }
log.Printf("fetched origin/%s", branch)
// Find the real commit for the rev. // Find the real commit for the rev.
output, err := runCommand(gitRoot, "git", "rev-list", "-n1", rev) output, err := runCommand(gitRoot, "git", "rev-list", "-n1", rev)
@ -222,7 +244,7 @@ func addWorktreeAndSwap(gitRoot, dest, branch, rev string) error {
} }
revhash := strings.Trim(string(output), "\n") revhash := strings.Trim(string(output), "\n")
if revhash != rev { if revhash != rev {
log.Printf("rev %s resolves to %s", rev, revhash) log.V(0).Infof("rev %s resolves to %s", rev, revhash)
} }
// Make a worktree for this exact git hash. // Make a worktree for this exact git hash.
@ -231,7 +253,7 @@ func addWorktreeAndSwap(gitRoot, dest, branch, rev string) error {
if err != nil { if err != nil {
return err return err
} }
log.Printf("added worktree %s for origin/%s", worktreePath, branch) log.V(0).Infof("added worktree %s for origin/%s", worktreePath, branch)
// The .git file in the worktree directory holds a reference to // The .git file in the worktree directory holds a reference to
// /git/.git/worktrees/<worktree-dir-name>. Replace it with a reference // /git/.git/worktrees/<worktree-dir-name>. Replace it with a reference
@ -251,7 +273,7 @@ func addWorktreeAndSwap(gitRoot, dest, branch, rev string) error {
if err != nil { if err != nil {
return err return err
} }
log.Printf("reset worktree %s to %s", worktreePath, rev) log.V(0).Infof("reset worktree %s to %s", worktreePath, rev)
if *flChmod != 0 { if *flChmod != 0 {
// set file permissions // set file permissions
@ -274,7 +296,7 @@ func cloneRepo(repo, branch, rev string, depth int, gitRoot string) error {
if err != nil { if err != nil {
return err return err
} }
log.Printf("cloned %s", repo) log.V(0).Infof("cloned %s", repo)
return nil return nil
} }
@ -310,9 +332,9 @@ func syncRepo(repo, branch, rev string, depth int, gitRoot, dest string) error {
return err return err
} }
if needed { if needed {
log.Printf("update required") log.V(0).Infof("update required")
} else { } else {
log.Printf("no update required") log.V(0).Infof("no update required")
return nil return nil
} }
} }
@ -330,7 +352,7 @@ func needResync(localDir, rev string) (bool, error) {
local = strings.Trim(local, "\n") local = strings.Trim(local, "\n")
// Fetch rev from upstream. // Fetch rev from upstream.
_, err := runCommand(localDir, "git", "fetch", "origin", rev) _, err = runCommand(localDir, "git", "fetch", "origin", rev)
if err != nil { if err != nil {
return false, err return false, err
} }
@ -342,8 +364,8 @@ func needResync(localDir, rev string) (bool, error) {
} }
remote = strings.Trim(remote, "\n") remote = strings.Trim(remote, "\n")
log.Printf("local hash: %s", local) log.V(2).Infof("local hash: %s", local)
log.Printf("remote hash: %s", remote) log.V(2).Infof("remote hash: %s", remote)
return (local != remote), nil return (local != remote), nil
} }
@ -360,7 +382,7 @@ func cmdForLog(command string, args ...string) string {
} }
func runCommand(cwd, command string, args ...string) (string, error) { func runCommand(cwd, command string, args ...string) (string, error) {
log.Printf("run(%q): %s", cwd, cmdForLog(command, args...)) log.V(5).Infof("run(%q): %s", cwd, cmdForLog(command, args...))
cmd := exec.Command(command, args...) cmd := exec.Command(command, args...)
if cwd != "" { if cwd != "" {
@ -375,7 +397,7 @@ func runCommand(cwd, command string, args ...string) (string, error) {
} }
func setupGitAuth(username, password, gitURL string) error { func setupGitAuth(username, password, gitURL string) error {
log.Println("setting up the git credential cache") log.V(1).Infof("setting up the git credential cache")
cmd := exec.Command("git", "config", "--global", "credential.helper", "cache") cmd := exec.Command("git", "config", "--global", "credential.helper", "cache")
output, err := cmd.CombinedOutput() output, err := cmd.CombinedOutput()
if err != nil { if err != nil {
@ -399,7 +421,7 @@ func setupGitAuth(username, password, gitURL string) error {
} }
func setupGitSSH() error { func setupGitSSH() error {
log.Println("setting up git SSH credentials") log.V(1).Infof("setting up git SSH credentials")
if _, err := os.Stat("/etc/git-secret/ssh"); err != nil { if _, err := os.Stat("/etc/git-secret/ssh"); err != nil {
return fmt.Errorf("error: could not find SSH key Secret: %v", err) return fmt.Errorf("error: could not find SSH key Secret: %v", err)

191
vendor/github.com/golang/glog/LICENSE generated vendored Normal file
View File

@ -0,0 +1,191 @@
Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/
TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
1. Definitions.
"License" shall mean the terms and conditions for use, reproduction, and
distribution as defined by Sections 1 through 9 of this document.
"Licensor" shall mean the copyright owner or entity authorized by the copyright
owner that is granting the License.
"Legal Entity" shall mean the union of the acting entity and all other entities
that control, are controlled by, or are under common control with that entity.
For the purposes of this definition, "control" means (i) the power, direct or
indirect, to cause the direction or management of such entity, whether by
contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the
outstanding shares, or (iii) beneficial ownership of such entity.
"You" (or "Your") shall mean an individual or Legal Entity exercising
permissions granted by this License.
"Source" form shall mean the preferred form for making modifications, including
but not limited to software source code, documentation source, and configuration
files.
"Object" form shall mean any form resulting from mechanical transformation or
translation of a Source form, including but not limited to compiled object code,
generated documentation, and conversions to other media types.
"Work" shall mean the work of authorship, whether in Source or Object form, made
available under the License, as indicated by a copyright notice that is included
in or attached to the work (an example is provided in the Appendix below).
"Derivative Works" shall mean any work, whether in Source or Object form, that
is based on (or derived from) the Work and for which the editorial revisions,
annotations, elaborations, or other modifications represent, as a whole, an
original work of authorship. For the purposes of this License, Derivative Works
shall not include works that remain separable from, or merely link (or bind by
name) to the interfaces of, the Work and Derivative Works thereof.
"Contribution" shall mean any work of authorship, including the original version
of the Work and any modifications or additions to that Work or Derivative Works
thereof, that is intentionally submitted to Licensor for inclusion in the Work
by the copyright owner or by an individual or Legal Entity authorized to submit
on behalf of the copyright owner. For the purposes of this definition,
"submitted" means any form of electronic, verbal, or written communication sent
to the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control systems, and
issue tracking systems that are managed by, or on behalf of, the Licensor for
the purpose of discussing and improving the Work, but excluding communication
that is conspicuously marked or otherwise designated in writing by the copyright
owner as "Not a Contribution."
"Contributor" shall mean Licensor and any individual or Legal Entity on behalf
of whom a Contribution has been received by Licensor and subsequently
incorporated within the Work.
2. Grant of Copyright License.
Subject to the terms and conditions of this License, each Contributor hereby
grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free,
irrevocable copyright license to reproduce, prepare Derivative Works of,
publicly display, publicly perform, sublicense, and distribute the Work and such
Derivative Works in Source or Object form.
3. Grant of Patent License.
Subject to the terms and conditions of this License, each Contributor hereby
grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free,
irrevocable (except as stated in this section) patent license to make, have
made, use, offer to sell, sell, import, and otherwise transfer the Work, where
such license applies only to those patent claims licensable by such Contributor
that are necessarily infringed by their Contribution(s) alone or by combination
of their Contribution(s) with the Work to which such Contribution(s) was
submitted. If You institute patent litigation against any entity (including a
cross-claim or counterclaim in a lawsuit) alleging that the Work or a
Contribution incorporated within the Work constitutes direct or contributory
patent infringement, then any patent licenses granted to You under this License
for that Work shall terminate as of the date such litigation is filed.
4. Redistribution.
You may reproduce and distribute copies of the Work or Derivative Works thereof
in any medium, with or without modifications, and in Source or Object form,
provided that You meet the following conditions:
You must give any other recipients of the Work or Derivative Works a copy of
this License; and
You must cause any modified files to carry prominent notices stating that You
changed the files; and
You must retain, in the Source form of any Derivative Works that You distribute,
all copyright, patent, trademark, and attribution notices from the Source form
of the Work, excluding those notices that do not pertain to any part of the
Derivative Works; and
If the Work includes a "NOTICE" text file as part of its distribution, then any
Derivative Works that You distribute must include a readable copy of the
attribution notices contained within such NOTICE file, excluding those notices
that do not pertain to any part of the Derivative Works, in at least one of the
following places: within a NOTICE text file distributed as part of the
Derivative Works; within the Source form or documentation, if provided along
with the Derivative Works; or, within a display generated by the Derivative
Works, if and wherever such third-party notices normally appear. The contents of
the NOTICE file are for informational purposes only and do not modify the
License. You may add Your own attribution notices within Derivative Works that
You distribute, alongside or as an addendum to the NOTICE text from the Work,
provided that such additional attribution notices cannot be construed as
modifying the License.
You may add Your own copyright statement to Your modifications and may provide
additional or different license terms and conditions for use, reproduction, or
distribution of Your modifications, or for any such Derivative Works as a whole,
provided Your use, reproduction, and distribution of the Work otherwise complies
with the conditions stated in this License.
5. Submission of Contributions.
Unless You explicitly state otherwise, any Contribution intentionally submitted
for inclusion in the Work by You to the Licensor shall be under the terms and
conditions of this License, without any additional terms or conditions.
Notwithstanding the above, nothing herein shall supersede or modify the terms of
any separate license agreement you may have executed with Licensor regarding
such Contributions.
6. Trademarks.
This License does not grant permission to use the trade names, trademarks,
service marks, or product names of the Licensor, except as required for
reasonable and customary use in describing the origin of the Work and
reproducing the content of the NOTICE file.
7. Disclaimer of Warranty.
Unless required by applicable law or agreed to in writing, Licensor provides the
Work (and each Contributor provides its Contributions) on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied,
including, without limitation, any warranties or conditions of TITLE,
NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are
solely responsible for determining the appropriateness of using or
redistributing the Work and assume any risks associated with Your exercise of
permissions under this License.
8. Limitation of Liability.
In no event and under no legal theory, whether in tort (including negligence),
contract, or otherwise, unless required by applicable law (such as deliberate
and grossly negligent acts) or agreed to in writing, shall any Contributor be
liable to You for damages, including any direct, indirect, special, incidental,
or consequential damages of any character arising as a result of this License or
out of the use or inability to use the Work (including but not limited to
damages for loss of goodwill, work stoppage, computer failure or malfunction, or
any and all other commercial damages or losses), even if such Contributor has
been advised of the possibility of such damages.
9. Accepting Warranty or Additional Liability.
While redistributing the Work or Derivative Works thereof, You may choose to
offer, and charge a fee for, acceptance of support, warranty, indemnity, or
other liability obligations and/or rights consistent with this License. However,
in accepting such obligations, You may act only on Your own behalf and on Your
sole responsibility, not on behalf of any other Contributor, and only if You
agree to indemnify, defend, and hold each Contributor harmless for any liability
incurred by, or claims asserted against, such Contributor by reason of your
accepting any such warranty or additional liability.
END OF TERMS AND CONDITIONS
APPENDIX: How to apply the Apache License to your work
To apply the Apache License to your work, attach the following boilerplate
notice, with the fields enclosed by brackets "[]" replaced with your own
identifying information. (Don't include the brackets!) The text should be
enclosed in the appropriate comment syntax for the file format. We also
recommend that a file or class name and description of purpose be included on
the same "printed page" as the copyright notice for easier identification within
third-party archives.
Copyright [yyyy] [name of copyright owner]
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

44
vendor/github.com/golang/glog/README generated vendored Normal file
View File

@ -0,0 +1,44 @@
glog
====
Leveled execution logs for Go.
This is an efficient pure Go implementation of leveled logs in the
manner of the open source C++ package
https://github.com/google/glog
By binding methods to booleans it is possible to use the log package
without paying the expense of evaluating the arguments to the log.
Through the -vmodule flag, the package also provides fine-grained
control over logging at the file level.
The comment from glog.go introduces the ideas:
Package glog implements logging analogous to the Google-internal
C++ INFO/ERROR/V setup. It provides functions Info, Warning,
Error, Fatal, plus formatting variants such as Infof. It
also provides V-style logging controlled by the -v and
-vmodule=file=2 flags.
Basic examples:
glog.Info("Prepare to repel boarders")
glog.Fatalf("Initialization failed: %s", err)
See the documentation for the V function for an explanation
of these examples:
if glog.V(2) {
glog.Info("Starting transaction...")
}
glog.V(2).Infoln("Processed", nItems, "elements")
The repository contains an open source version of the log package
used inside Google. The master copy of the source lives inside
Google, not here. The code in this repo is for export only and is not itself
under development. Feature requests will be ignored.
Send bug reports to golang-nuts@googlegroups.com.

1180
vendor/github.com/golang/glog/glog.go generated vendored Normal file
View File

File diff suppressed because it is too large Load Diff

124
vendor/github.com/golang/glog/glog_file.go generated vendored Normal file
View File

@ -0,0 +1,124 @@
// Go support for leveled logs, analogous to https://code.google.com/p/google-glog/
//
// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// File I/O for logs.
package glog
import (
"errors"
"flag"
"fmt"
"os"
"os/user"
"path/filepath"
"strings"
"sync"
"time"
)
// MaxSize is the maximum size of a log file in bytes.
var MaxSize uint64 = 1024 * 1024 * 1800
// logDirs lists the candidate directories for new log files.
var logDirs []string
// If non-empty, overrides the choice of directory in which to write logs.
// See createLogDirs for the full list of possible destinations.
var logDir = flag.String("log_dir", "", "If non-empty, write log files in this directory")
func createLogDirs() {
if *logDir != "" {
logDirs = append(logDirs, *logDir)
}
logDirs = append(logDirs, os.TempDir())
}
var (
pid = os.Getpid()
program = filepath.Base(os.Args[0])
host = "unknownhost"
userName = "unknownuser"
)
func init() {
h, err := os.Hostname()
if err == nil {
host = shortHostname(h)
}
current, err := user.Current()
if err == nil {
userName = current.Username
}
// Sanitize userName since it may contain filepath separators on Windows.
userName = strings.Replace(userName, `\`, "_", -1)
}
// shortHostname returns its argument, truncating at the first period.
// For instance, given "www.google.com" it returns "www".
func shortHostname(hostname string) string {
if i := strings.Index(hostname, "."); i >= 0 {
return hostname[:i]
}
return hostname
}
// logName returns a new log file name containing tag, with start time t, and
// the name for the symlink for tag.
func logName(tag string, t time.Time) (name, link string) {
name = fmt.Sprintf("%s.%s.%s.log.%s.%04d%02d%02d-%02d%02d%02d.%d",
program,
host,
userName,
tag,
t.Year(),
t.Month(),
t.Day(),
t.Hour(),
t.Minute(),
t.Second(),
pid)
return name, program + "." + tag
}
var onceLogDirs sync.Once
// create creates a new log file and returns the file and its filename, which
// contains tag ("INFO", "FATAL", etc.) and t. If the file is created
// successfully, create also attempts to update the symlink for that tag, ignoring
// errors.
func create(tag string, t time.Time) (f *os.File, filename string, err error) {
onceLogDirs.Do(createLogDirs)
if len(logDirs) == 0 {
return nil, "", errors.New("log: no log dirs")
}
name, link := logName(tag, t)
var lastErr error
for _, dir := range logDirs {
fname := filepath.Join(dir, name)
f, err := os.Create(fname)
if err == nil {
symlink := filepath.Join(dir, link)
os.Remove(symlink) // ignore err
os.Symlink(name, symlink) // ignore err
return f, fname, nil
}
lastErr = err
}
return nil, "", fmt.Errorf("log: cannot create log: %v", lastErr)
}

201
vendor/github.com/thockin/glogr/LICENSE generated vendored Normal file
View File

@ -0,0 +1,201 @@
Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/
TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
1. Definitions.
"License" shall mean the terms and conditions for use, reproduction,
and distribution as defined by Sections 1 through 9 of this document.
"Licensor" shall mean the copyright owner or entity authorized by
the copyright owner that is granting the License.
"Legal Entity" shall mean the union of the acting entity and all
other entities that control, are controlled by, or are under common
control with that entity. For the purposes of this definition,
"control" means (i) the power, direct or indirect, to cause the
direction or management of such entity, whether by contract or
otherwise, or (ii) ownership of fifty percent (50%) or more of the
outstanding shares, or (iii) beneficial ownership of such entity.
"You" (or "Your") shall mean an individual or Legal Entity
exercising permissions granted by this License.
"Source" form shall mean the preferred form for making modifications,
including but not limited to software source code, documentation
source, and configuration files.
"Object" form shall mean any form resulting from mechanical
transformation or translation of a Source form, including but
not limited to compiled object code, generated documentation,
and conversions to other media types.
"Work" shall mean the work of authorship, whether in Source or
Object form, made available under the License, as indicated by a
copyright notice that is included in or attached to the work
(an example is provided in the Appendix below).
"Derivative Works" shall mean any work, whether in Source or Object
form, that is based on (or derived from) the Work and for which the
editorial revisions, annotations, elaborations, or other modifications
represent, as a whole, an original work of authorship. For the purposes
of this License, Derivative Works shall not include works that remain
separable from, or merely link (or bind by name) to the interfaces of,
the Work and Derivative Works thereof.
"Contribution" shall mean any work of authorship, including
the original version of the Work and any modifications or additions
to that Work or Derivative Works thereof, that is intentionally
submitted to Licensor for inclusion in the Work by the copyright owner
or by an individual or Legal Entity authorized to submit on behalf of
the copyright owner. For the purposes of this definition, "submitted"
means any form of electronic, verbal, or written communication sent
to the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control systems,
and issue tracking systems that are managed by, or on behalf of, the
Licensor for the purpose of discussing and improving the Work, but
excluding communication that is conspicuously marked or otherwise
designated in writing by the copyright owner as "Not a Contribution."
"Contributor" shall mean Licensor and any individual or Legal Entity
on behalf of whom a Contribution has been received by Licensor and
subsequently incorporated within the Work.
2. Grant of Copyright License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
copyright license to reproduce, prepare Derivative Works of,
publicly display, publicly perform, sublicense, and distribute the
Work and such Derivative Works in Source or Object form.
3. Grant of Patent License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
(except as stated in this section) patent license to make, have made,
use, offer to sell, sell, import, and otherwise transfer the Work,
where such license applies only to those patent claims licensable
by such Contributor that are necessarily infringed by their
Contribution(s) alone or by combination of their Contribution(s)
with the Work to which such Contribution(s) was submitted. If You
institute patent litigation against any entity (including a
cross-claim or counterclaim in a lawsuit) alleging that the Work
or a Contribution incorporated within the Work constitutes direct
or contributory patent infringement, then any patent licenses
granted to You under this License for that Work shall terminate
as of the date such litigation is filed.
4. Redistribution. You may reproduce and distribute copies of the
Work or Derivative Works thereof in any medium, with or without
modifications, and in Source or Object form, provided that You
meet the following conditions:
(a) You must give any other recipients of the Work or
Derivative Works a copy of this License; and
(b) You must cause any modified files to carry prominent notices
stating that You changed the files; and
(c) You must retain, in the Source form of any Derivative Works
that You distribute, all copyright, patent, trademark, and
attribution notices from the Source form of the Work,
excluding those notices that do not pertain to any part of
the Derivative Works; and
(d) If the Work includes a "NOTICE" text file as part of its
distribution, then any Derivative Works that You distribute must
include a readable copy of the attribution notices contained
within such NOTICE file, excluding those notices that do not
pertain to any part of the Derivative Works, in at least one
of the following places: within a NOTICE text file distributed
as part of the Derivative Works; within the Source form or
documentation, if provided along with the Derivative Works; or,
within a display generated by the Derivative Works, if and
wherever such third-party notices normally appear. The contents
of the NOTICE file are for informational purposes only and
do not modify the License. You may add Your own attribution
notices within Derivative Works that You distribute, alongside
or as an addendum to the NOTICE text from the Work, provided
that such additional attribution notices cannot be construed
as modifying the License.
You may add Your own copyright statement to Your modifications and
may provide additional or different license terms and conditions
for use, reproduction, or distribution of Your modifications, or
for any such Derivative Works as a whole, provided Your use,
reproduction, and distribution of the Work otherwise complies with
the conditions stated in this License.
5. Submission of Contributions. Unless You explicitly state otherwise,
any Contribution intentionally submitted for inclusion in the Work
by You to the Licensor shall be under the terms and conditions of
this License, without any additional terms or conditions.
Notwithstanding the above, nothing herein shall supersede or modify
the terms of any separate license agreement you may have executed
with Licensor regarding such Contributions.
6. Trademarks. This License does not grant permission to use the trade
names, trademarks, service marks, or product names of the Licensor,
except as required for reasonable and customary use in describing the
origin of the Work and reproducing the content of the NOTICE file.
7. Disclaimer of Warranty. Unless required by applicable law or
agreed to in writing, Licensor provides the Work (and each
Contributor provides its Contributions) on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied, including, without limitation, any warranties or conditions
of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
PARTICULAR PURPOSE. You are solely responsible for determining the
appropriateness of using or redistributing the Work and assume any
risks associated with Your exercise of permissions under this License.
8. Limitation of Liability. In no event and under no legal theory,
whether in tort (including negligence), contract, or otherwise,
unless required by applicable law (such as deliberate and grossly
negligent acts) or agreed to in writing, shall any Contributor be
liable to You for damages, including any direct, indirect, special,
incidental, or consequential damages of any character arising as a
result of this License or out of the use or inability to use the
Work (including but not limited to damages for loss of goodwill,
work stoppage, computer failure or malfunction, or any and all
other commercial damages or losses), even if such Contributor
has been advised of the possibility of such damages.
9. Accepting Warranty or Additional Liability. While redistributing
the Work or Derivative Works thereof, You may choose to offer,
and charge a fee for, acceptance of support, warranty, indemnity,
or other liability obligations and/or rights consistent with this
License. However, in accepting such obligations, You may act only
on Your own behalf and on Your sole responsibility, not on behalf
of any other Contributor, and only if You agree to indemnify,
defend, and hold each Contributor harmless for any liability
incurred by, or claims asserted against, such Contributor by reason
of your accepting any such warranty or additional liability.
END OF TERMS AND CONDITIONS
APPENDIX: How to apply the Apache License to your work.
To apply the Apache License to your work, attach the following
boilerplate notice, with the fields enclosed by brackets "{}"
replaced with your own identifying information. (Don't include
the brackets!) The text should be enclosed in the appropriate
comment syntax for the file format. We also recommend that a
file or class name and description of purpose be included on the
same "printed page" as the copyright notice for easier
identification within third-party archives.
Copyright {yyyy} {name of copyright owner}
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

8
vendor/github.com/thockin/glogr/README.md generated vendored Normal file
View File

@ -0,0 +1,8 @@
# Minimal Go logging using glog
This package implements the [logr interface](https://github.com/thockin/logr)
in terms of Google's [glog](https://godoc.org/github.com/golang/glog). This
provides a relatively minimalist API to logging in Go, backed by a well-proven
implementation.
This is a BETA grade implementation.

86
vendor/github.com/thockin/glogr/glogr.go generated vendored Normal file
View File

@ -0,0 +1,86 @@
// Package glogr implements github.com/thockin/logr.Logger in terms of
// github.com/golang/glog.
package glogr
import (
"fmt"
"runtime"
"github.com/golang/glog"
"github.com/thockin/logr"
)
// New returns a logr.Logger which is implemented by glog.
func New() (logr.Logger, error) {
return glogger{
level: 0,
prefix: "",
}, nil
}
type glogger struct {
level int
prefix string
}
func prepend(prefix interface{}, args []interface{}) []interface{} {
return append([]interface{}{prefix}, args...)
}
// Magic string for intermediate frames that we should ignore.
const autogeneratedFrameName = "<autogenerated>"
// Discover how many frames we need to climb to find the caller. This approach
// was suggested by Ian Lance Taylor of the Go team, so it *should* be safe
// enough (famous last words).
func framesToCaller() int {
// 1 is the immediate caller. 3 should be too many.
for i := 1; i < 3; i++ {
_, file, _, _ := runtime.Caller(i + 1) // +1 for this function's frame
if file != autogeneratedFrameName {
return i
}
}
return 1 // something went wrong, this is safe
}
func (l glogger) Info(args ...interface{}) {
if l.Enabled() {
glog.InfoDepth(framesToCaller(), prepend(l.prefix, args)...)
}
}
func (l glogger) Infof(format string, args ...interface{}) {
if l.Enabled() {
glog.InfoDepth(framesToCaller(), fmt.Sprintf("%s"+format, prepend(l.prefix, args)...))
}
}
func (l glogger) Enabled() bool {
return bool(glog.V(glog.Level(l.level)))
}
func (l glogger) Error(args ...interface{}) {
glog.ErrorDepth(framesToCaller(), prepend(l.prefix, args)...)
}
func (l glogger) Errorf(format string, args ...interface{}) {
glog.ErrorDepth(framesToCaller(), fmt.Sprintf("%s"+format, prepend(l.prefix, args)...))
}
func (l glogger) V(level int) logr.InfoLogger {
return glogger{
level: level,
prefix: l.prefix,
}
}
func (l glogger) NewWithPrefix(prefix string) logr.Logger {
return glogger{
level: l.level,
prefix: prefix,
}
}
var _ logr.Logger = glogger{}
var _ logr.InfoLogger = glogger{}

201
vendor/github.com/thockin/logr/LICENSE generated vendored Normal file
View File

@ -0,0 +1,201 @@
Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/
TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
1. Definitions.
"License" shall mean the terms and conditions for use, reproduction,
and distribution as defined by Sections 1 through 9 of this document.
"Licensor" shall mean the copyright owner or entity authorized by
the copyright owner that is granting the License.
"Legal Entity" shall mean the union of the acting entity and all
other entities that control, are controlled by, or are under common
control with that entity. For the purposes of this definition,
"control" means (i) the power, direct or indirect, to cause the
direction or management of such entity, whether by contract or
otherwise, or (ii) ownership of fifty percent (50%) or more of the
outstanding shares, or (iii) beneficial ownership of such entity.
"You" (or "Your") shall mean an individual or Legal Entity
exercising permissions granted by this License.
"Source" form shall mean the preferred form for making modifications,
including but not limited to software source code, documentation
source, and configuration files.
"Object" form shall mean any form resulting from mechanical
transformation or translation of a Source form, including but
not limited to compiled object code, generated documentation,
and conversions to other media types.
"Work" shall mean the work of authorship, whether in Source or
Object form, made available under the License, as indicated by a
copyright notice that is included in or attached to the work
(an example is provided in the Appendix below).
"Derivative Works" shall mean any work, whether in Source or Object
form, that is based on (or derived from) the Work and for which the
editorial revisions, annotations, elaborations, or other modifications
represent, as a whole, an original work of authorship. For the purposes
of this License, Derivative Works shall not include works that remain
separable from, or merely link (or bind by name) to the interfaces of,
the Work and Derivative Works thereof.
"Contribution" shall mean any work of authorship, including
the original version of the Work and any modifications or additions
to that Work or Derivative Works thereof, that is intentionally
submitted to Licensor for inclusion in the Work by the copyright owner
or by an individual or Legal Entity authorized to submit on behalf of
the copyright owner. For the purposes of this definition, "submitted"
means any form of electronic, verbal, or written communication sent
to the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control systems,
and issue tracking systems that are managed by, or on behalf of, the
Licensor for the purpose of discussing and improving the Work, but
excluding communication that is conspicuously marked or otherwise
designated in writing by the copyright owner as "Not a Contribution."
"Contributor" shall mean Licensor and any individual or Legal Entity
on behalf of whom a Contribution has been received by Licensor and
subsequently incorporated within the Work.
2. Grant of Copyright License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
copyright license to reproduce, prepare Derivative Works of,
publicly display, publicly perform, sublicense, and distribute the
Work and such Derivative Works in Source or Object form.
3. Grant of Patent License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
(except as stated in this section) patent license to make, have made,
use, offer to sell, sell, import, and otherwise transfer the Work,
where such license applies only to those patent claims licensable
by such Contributor that are necessarily infringed by their
Contribution(s) alone or by combination of their Contribution(s)
with the Work to which such Contribution(s) was submitted. If You
institute patent litigation against any entity (including a
cross-claim or counterclaim in a lawsuit) alleging that the Work
or a Contribution incorporated within the Work constitutes direct
or contributory patent infringement, then any patent licenses
granted to You under this License for that Work shall terminate
as of the date such litigation is filed.
4. Redistribution. You may reproduce and distribute copies of the
Work or Derivative Works thereof in any medium, with or without
modifications, and in Source or Object form, provided that You
meet the following conditions:
(a) You must give any other recipients of the Work or
Derivative Works a copy of this License; and
(b) You must cause any modified files to carry prominent notices
stating that You changed the files; and
(c) You must retain, in the Source form of any Derivative Works
that You distribute, all copyright, patent, trademark, and
attribution notices from the Source form of the Work,
excluding those notices that do not pertain to any part of
the Derivative Works; and
(d) If the Work includes a "NOTICE" text file as part of its
distribution, then any Derivative Works that You distribute must
include a readable copy of the attribution notices contained
within such NOTICE file, excluding those notices that do not
pertain to any part of the Derivative Works, in at least one
of the following places: within a NOTICE text file distributed
as part of the Derivative Works; within the Source form or
documentation, if provided along with the Derivative Works; or,
within a display generated by the Derivative Works, if and
wherever such third-party notices normally appear. The contents
of the NOTICE file are for informational purposes only and
do not modify the License. You may add Your own attribution
notices within Derivative Works that You distribute, alongside
or as an addendum to the NOTICE text from the Work, provided
that such additional attribution notices cannot be construed
as modifying the License.
You may add Your own copyright statement to Your modifications and
may provide additional or different license terms and conditions
for use, reproduction, or distribution of Your modifications, or
for any such Derivative Works as a whole, provided Your use,
reproduction, and distribution of the Work otherwise complies with
the conditions stated in this License.
5. Submission of Contributions. Unless You explicitly state otherwise,
any Contribution intentionally submitted for inclusion in the Work
by You to the Licensor shall be under the terms and conditions of
this License, without any additional terms or conditions.
Notwithstanding the above, nothing herein shall supersede or modify
the terms of any separate license agreement you may have executed
with Licensor regarding such Contributions.
6. Trademarks. This License does not grant permission to use the trade
names, trademarks, service marks, or product names of the Licensor,
except as required for reasonable and customary use in describing the
origin of the Work and reproducing the content of the NOTICE file.
7. Disclaimer of Warranty. Unless required by applicable law or
agreed to in writing, Licensor provides the Work (and each
Contributor provides its Contributions) on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied, including, without limitation, any warranties or conditions
of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
PARTICULAR PURPOSE. You are solely responsible for determining the
appropriateness of using or redistributing the Work and assume any
risks associated with Your exercise of permissions under this License.
8. Limitation of Liability. In no event and under no legal theory,
whether in tort (including negligence), contract, or otherwise,
unless required by applicable law (such as deliberate and grossly
negligent acts) or agreed to in writing, shall any Contributor be
liable to You for damages, including any direct, indirect, special,
incidental, or consequential damages of any character arising as a
result of this License or out of the use or inability to use the
Work (including but not limited to damages for loss of goodwill,
work stoppage, computer failure or malfunction, or any and all
other commercial damages or losses), even if such Contributor
has been advised of the possibility of such damages.
9. Accepting Warranty or Additional Liability. While redistributing
the Work or Derivative Works thereof, You may choose to offer,
and charge a fee for, acceptance of support, warranty, indemnity,
or other liability obligations and/or rights consistent with this
License. However, in accepting such obligations, You may act only
on Your own behalf and on Your sole responsibility, not on behalf
of any other Contributor, and only if You agree to indemnify,
defend, and hold each Contributor harmless for any liability
incurred by, or claims asserted against, such Contributor by reason
of your accepting any such warranty or additional liability.
END OF TERMS AND CONDITIONS
APPENDIX: How to apply the Apache License to your work.
To apply the Apache License to your work, attach the following
boilerplate notice, with the fields enclosed by brackets "{}"
replaced with your own identifying information. (Don't include
the brackets!) The text should be enclosed in the appropriate
comment syntax for the file format. We also recommend that a
file or class name and description of purpose be included on the
same "printed page" as the copyright notice for easier
identification within third-party archives.
Copyright {yyyy} {name of copyright owner}
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

36
vendor/github.com/thockin/logr/README.md generated vendored Normal file
View File

@ -0,0 +1,36 @@
# A more minimal logging API for Go
Before you consider this package, please read [this blog post by the inimitable
Dave Cheney](http://dave.cheney.net/2015/11/05/lets-talk-about-logging). I
really appreciate what he has to say, and it largely aligns with my own
experiences. Too many choices of levels means inconsistent logs.
This package offers a purely abstract interface, based on these ideas but with
a few twists. Code can depend on just this interface and have the actual
logging implementation be injected from callers. Ideally only `main()` knows
what logging implementation is being used.
# Differences from Dave's ideas
The main differences are:
1) Dave basically proposes doing away with the notion of a logging API in favor
of `fmt.Printf()`. I disagree, especially when you consider things like output
locations, timestamps, file and line decorations, and structured logging. I
restrict the API to just 2 types of logs: info and error.
Info logs are things you want to tell the user which are not errors. Error
logs are, well, errors. If your code receives an `error` from a subordinate
function call and is logging that `error` *and not returning it*, use error
logs.
2) Verbosity-levels on info logs. This gives developers a chance to indicate
arbitrary grades of importance for info logs, without assigning names with
semantic meaning such as "warning", "trace", and "debug". Superficially this
may feel very similar, but the primary difference is the lack of semantics.
Because verbosity is a numerical value, it's safe to assume that an app running
with higher verbosity means more (and less important) logs will be generated.
This is a BETA grade API. I have implemented it for
[glog](https://godoc.org/github.com/golang/glog). Until there is a significant
2nd implementation, I don't really know how it will change.

48
vendor/github.com/thockin/logr/logr.go generated vendored Normal file
View File

@ -0,0 +1,48 @@
// Package logr defines abstract interfaces for logging. Packages can depend on
// these interfaces and callers can implement logging in whatever way is
// appropriate.
//
// This design derives from Dave Cheney's blog:
// http://dave.cheney.net/2015/11/05/lets-talk-about-logging
//
// This is a BETA grade API. Until there is a significant 2nd implementation,
// I don't really know how it will change.
package logr
// TODO: consider structured logging, a la uber-go/zap
// TODO: consider other bits of glog functionality like Flush, InfoDepth, OutputStats
// InfoLogger represents the ability to log non-error messages.
type InfoLogger interface {
// Info logs a non-error message. This is behaviorally akin to fmt.Print.
Info(args ...interface{})
// Infof logs a formatted non-error message.
Infof(format string, args ...interface{})
// Enabled test whether this InfoLogger is enabled. For example,
// commandline flags might be used to set the logging verbosity and disable
// some info logs.
Enabled() bool
}
// Logger represents the ability to log messages, both errors and not.
type Logger interface {
// All Loggers implement InfoLogger. Calling InfoLogger methods directly on
// a Logger value is equivalent to calling them on a V(0) InfoLogger. For
// example, logger.Info() produces the same result as logger.V(0).Info.
InfoLogger
// Error logs a error message. This is behaviorally akin to fmt.Print.
Error(args ...interface{})
// Errorf logs a formatted error message.
Errorf(format string, args ...interface{})
// V returns an InfoLogger value for a specific verbosity level. A higher
// verbosity level means a log message is less important.
V(level int) InfoLogger
// NewWithPrefix returns a Logger which prefixes all messages.
NewWithPrefix(prefix string) Logger
}