func/docker/pusher.go

94 lines
2.2 KiB
Go

package docker
import (
"bytes"
"errors"
"fmt"
"io"
"os"
"os/exec"
"strings"
bosonFunc "github.com/boson-project/func"
)
// Pusher of images from local to remote registry.
type Pusher struct {
// Verbose logging.
Verbose bool
}
// NewPusher creates an instance of a docker-based image pusher.
func NewPusher() *Pusher {
return &Pusher{}
}
// Push the image of the Function.
func (n *Pusher) Push(f bosonFunc.Function) (digest string, err error) {
// Check for the docker binary explicitly so that we can return
// an extra-friendly error message.
_, err = exec.LookPath("docker")
if err != nil {
err = errors.New("please install 'docker'")
return
}
if f.Image == "" {
return "", errors.New("Function has no associated image. Has it been built?")
}
// set up the command, specifying a sanitized project name and connecting
// standard output and error.
cmd := exec.Command("docker", "push", f.Image)
// Capture the command output in the buffer
var output bytes.Buffer
// If verbose logging is enabled, echo chatty stdout.
if n.Verbose {
fmt.Println(cmd)
cmd.Stdout = io.MultiWriter(&output, os.Stdout)
} else {
cmd.Stdout = &output
}
// Capture stderr for echoing on failure.
var stderr bytes.Buffer
cmd.Stderr = &stderr
// Run the command, echoing captured stderr as well ass the cmd internal error.
err = cmd.Run()
if err != nil {
// TODO: sanitize stderr from docker?
err = fmt.Errorf("%v. %v", stderr.String(), err.Error())
}
digest = parseDigest(output.String())
return
}
// parseDigest tries to parse the last line from the output, which holds the pushed image digest
// The last line should look like this:
// latest: digest: sha256:a278a91112d17f8bde6b5f802a3317c7c752cf88078dae6f4b5a0784deb81782 size: 2613
func parseDigest(output string) string {
// get last line from the output
lines := strings.Split(output, "\n")
lastline := lines[len(lines)-2]
// find the start index of the "digest" section
shaIndex := strings.Index(lastline, "sha256")
if shaIndex == -1 {
return ""
}
subStr := lastline[shaIndex:]
// find the end index of the "digest" section
endIndex := strings.Index(subStr, " ")
if endIndex == -1 {
return ""
}
return subStr[:endIndex]
}