Generate systemd unit files for containers

the podman generate systemd command will generate a systemd unit file
based on the attributes of an existing container and user inputs.  the
command outputs the unit file to stdout for the user to copy or
redirect.  it is enabled for the remote client as well.

users can set a restart policy as well as define a stop timeout
override for the container.

Signed-off-by: baude <bbaude@redhat.com>

cmd/podman/cliconfig/config.go

@@ -136,12 +136,18 @@ type ExportValues struct {
 	PodmanCommand
 	Output string
 }
-
 type GenerateKubeValues struct {
 	PodmanCommand
 	Service bool
 }
 
+type GenerateSystemdValues struct {
+	PodmanCommand
+	Name          bool
+	RestartPolicy string
+	StopTimeout   int
+}
+
 type HistoryValues struct {
 	PodmanCommand
 	Human   bool

cmd/podman/generate.go

@@ -18,6 +18,7 @@ var (
 	//	Commands that are universally implemented
 	generateCommands = []*cobra.Command{
 		_containerKubeCommand,
+		_containerSystemdCommand,
 	}
 )
 

cmd/podman/generate_systemd.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/containers/libpod/cmd/podman/cliconfig"
+	"github.com/containers/libpod/pkg/adapter"
+	"github.com/containers/libpod/pkg/systemdgen"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+)
+
+var (
+	containerSystemdCommand     cliconfig.GenerateSystemdValues
+	containerSystemdDescription = `Command generates a systemd unit file for a Podman container
+  `
+	_containerSystemdCommand = &cobra.Command{
+		Use:   "systemd [flags] CONTAINER | POD",
+		Short: "Generate a systemd unit file for a Podman container",
+		Long:  containerSystemdDescription,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			containerSystemdCommand.InputArgs = args
+			containerSystemdCommand.GlobalFlags = MainGlobalOpts
+			containerSystemdCommand.Remote = remoteclient
+			return generateSystemdCmd(&containerSystemdCommand)
+		},
+		Args: func(cmd *cobra.Command, args []string) error {
+			if len(args) > 1 || len(args) < 1 {
+				return errors.New("provide only one container name or ID")
+			}
+			return nil
+		},
+		Example: `podman generate kube ctrID
+`,
+	}
+)
+
+func init() {
+	containerSystemdCommand.Command = _containerSystemdCommand
+	containerSystemdCommand.SetHelpTemplate(HelpTemplate())
+	containerSystemdCommand.SetUsageTemplate(UsageTemplate())
+	flags := containerSystemdCommand.Flags()
+	flags.BoolVarP(&containerSystemdCommand.Name, "name", "n", false, "use the container name instead of ID")
+	flags.IntVarP(&containerSystemdCommand.StopTimeout, "timeout", "t", -1, "stop timeout override")
+	flags.StringVar(&containerSystemdCommand.RestartPolicy, "restart-policy", "on-failure", "applicable systemd restart-policy")
+}
+
+func generateSystemdCmd(c *cliconfig.GenerateSystemdValues) error {
+	runtime, err := adapter.GetRuntime(getContext(), &c.PodmanCommand)
+	if err != nil {
+		return errors.Wrapf(err, "could not get runtime")
+	}
+	defer runtime.Shutdown(false)
+
+	// User input stop timeout must be 0 or greater
+	if c.Flag("timeout").Changed && c.StopTimeout < 0 {
+		return errors.New("timeout value must be 0 or greater")
+	}
+	// Make sure the input restart policy is valid
+	if err := systemdgen.ValidateRestartPolicy(c.RestartPolicy); err != nil {
+		return err
+	}
+
+	unit, err := runtime.GenerateSystemd(c)
+	if err != nil {
+		return err
+	}
+	fmt.Println(unit)
+	return nil
+}

cmd/podman/varlink/io.podman.varlink

@@ -1218,6 +1218,8 @@ method GetLayersMapWithImageInfo() -> (layerMap: string)
 # BuildImageHierarchyMap is for the development of Podman and should not be used.
 method BuildImageHierarchyMap(name: string) -> (imageInfo: string)
 
+method GenerateSystemd(name: string, restart: string, timeout: int, useName: bool) -> (unit: string)
+
 # ImageNotFound means the image could not be found by the provided name or ID in local storage.
 error ImageNotFound (id: string, reason: string)
 

commands.md

@@ -25,6 +25,8 @@ Command                                                                  | Descr
 [podman-exec(1)](/docs/podman-exec.1.md)                                 | Execute a command in a running container                                   |
 [podman-export(1)](/docs/podman-export.1.md)                             | Export container's filesystem contents as a tar archive                    |
 [podman-generate(1)](/docs/podman-generate.1.md)                         | Generate structured output based on Podman containers and pods             |
+[podman-generate-kube(1)](/docs/podman-generate-kube.1.md)               | Generate Kubernetes YAML based on a container or Pod             |
+[podman-generate-systemd(1)](/docs/podman-generate-systemd.1.md)         | Generate a Systemd unit file for a container             |
 [podman-history(1)](/docs/podman-history.1.md)                           | Shows the history of an image                                              |
 [podman-image(1)](/docs/podman-image.1.md)                               | Manage Images                                                              |
 [podman-image-exists(1)](/docs/podman-image-exists.1.md)                 | Check if an image exists in local storage                                  |

completions/bash/podman

@@ -919,6 +919,7 @@ _podman_generate() {
 	"
      subcommands="
 	 kube
+	 systemd
      "
      __podman_subcommands "$subcommands $aliases" && return
 
@@ -2460,6 +2461,32 @@ _podman_generate_kube() {
     esac
 }
 
+_podman_generate_systemd() {
+    local options_with_args="
+    --restart-policy
+    -t
+    --timeout"
+
+    local boolean_options="
+    -h
+    --help
+    -n
+    --name
+    "
+
+    case "$cur" in
+	-*)
+	    COMPREPLY=($(compgen -W "$boolean_options $options_with_args" -- "$cur"))
+	    ;;
+	*)
+	    COMPREPLY=( $( compgen -W "
+			  $(__podman_containers --all)
+			  " -- "$cur" ) )
+	    __ltrim_colon_completions "$cur"
+	    ;;
+    esac
+}
+
 _podman_play_kube() {
     local options_with_args="
     --authfile

docs/podman-generate-systemd.1.md

@@ -0,0 +1,69 @@
+% podman-generate Podman Man Pages
+% Brent Baude
+% April 2019
+# NAME
+podman-generate-systemd- Generate Systemd Unit file
+
+# SYNOPSIS
+**podman generate systemd** [*-n*|*--name*] [*-t*|*--timeout*] [*--restart-policy*] *container*
+
+# DESCRIPTION
+**podman generate systemd** will create a Systemd unit file that can be used to control a container.  The
+command will dynamically create the unit file and output it to stdout where it can be piped by the user
+to a file.  The options can be used to influence the results of the output as well.
+
+
+# OPTIONS:
+
+**--name** **-n**
+
+Use the name of the container for the start, stop, and description in the unit file
+
+**--timeout** **-t**
+
+Override the default stop timeout for the container with the given value.
+
+**--restart-policy**
+Set the SystemD restart policy.  The restart-policy must be one of: "no", "on-success", "on-failure", "on-abnormal",
+"on-watchdog", "on-abort", or "always".  The default policy is *on-failure*.
+
+## Examples ##
+
+Create a systemd unit file for a container running nginx:
+
+```
+$ sudo podman generate systemd nginx
+[Unit]
+Description=c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc Podman Container
+[Service]
+Restart=on-failure
+ExecStart=/usr/bin/podman start c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc
+ExecStop=/usr/bin/podman stop -t 10 c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc
+KillMode=none
+Type=forking
+PIDFile=/var/lib/containers/storage/overlay-containers/c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc/userdata/c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc.pid
+[Install]
+WantedBy=multi-user.target
+```
+
+Create a systemd unit file for a container running nginx with an *always* restart policy and 1-second timeout.
+```
+$ sudo podman generate systemd --restart-policy=always -t 1 nginx
+[Unit]
+Description=c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc Podman Container
+[Service]
+Restart=always
+ExecStart=/usr/bin/podman start c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc
+ExecStop=/usr/bin/podman stop -t 1 c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc
+KillMode=none
+Type=forking
+PIDFile=/var/lib/containers/storage/overlay-containers/c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc/userdata/c21da63c4783be2ac2cd3487ef8d2ec15ee2a28f63dd8f145e3b05607f31cffc.pid
+[Install]
+WantedBy=multi-user.target
+```
+
+## SEE ALSO
+podman(1), podman-container(1)
+
+# HISTORY
+April 2019, Originally compiled by Brent Baude (bbaude at redhat dot com)

docs/podman-generate.1.md

@@ -14,6 +14,7 @@ The generate command will create structured output (like YAML) based on a contai
 | Command  | Man Page                                            | Description                                                                  |
 | -------  | --------------------------------------------------- | ---------------------------------------------------------------------------- |
 | kube     | [podman-generate-kube(1)](podman-generate-kube.1.md)| Generate Kubernetes YAML based on a pod or container.                        |
+| systemd  | [podman-generate-systemd(1)](podman-generate-systemd.1.md)| Generate a systemd unit file for a container.                        |
 
 ## SEE ALSO
 podman, podman-pod, podman-container

docs/podman-run.1.md

@@ -593,7 +593,7 @@ Not implemented.
 
 Restart should be handled via a systemd unit files. Please add your podman
 commands to a unit file and allow systemd or your init system to handle the
-restarting of the container processes. See example below.
+restarting of the container processes. See *podman generate systemd*.
 
 **--rm**=*true*|*false*
 
@@ -1151,21 +1151,6 @@ the uids and gids from the host.
 $ podman run --uidmap 0:30000:7000 --gidmap 0:30000:7000 fedora echo hello
 ```
 
-### Running a podman container to restart inside of a systemd unit file
-
-
-```
-[Unit]
-Description=My App
-[Service]
-Restart=always
-ExecStart=/usr/bin/podman start -a my_app
-ExecStop=/usr/bin/podman stop -t 10 my_app
-KillMode=process
-[Install]
-WantedBy=multi-user.target
-```
-
 ### Configuring Storage Options from the command line
 
 Podman allows for the configuration of storage by changing the values

pkg/adapter/containers.go

@@ -18,6 +18,7 @@ import (
 	"github.com/containers/libpod/cmd/podman/shared"
 	"github.com/containers/libpod/libpod"
 	"github.com/containers/libpod/pkg/adapter/shortcuts"
+	"github.com/containers/libpod/pkg/systemdgen"
 	"github.com/containers/storage"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -940,3 +941,20 @@ func (r *LocalRuntime) Port(c *cliconfig.PortValues) ([]*Container, error) {
 	}
 	return portContainers, nil
 }
+
+// GenerateSystemd creates a unit file for a container
+func (r *LocalRuntime) GenerateSystemd(c *cliconfig.GenerateSystemdValues) (string, error) {
+	ctr, err := r.Runtime.LookupContainer(c.InputArgs[0])
+	if err != nil {
+		return "", err
+	}
+	timeout := int(ctr.StopTimeout())
+	if c.StopTimeout >= 0 {
+		timeout = int(c.StopTimeout)
+	}
+	name := ctr.ID()
+	if c.Name {
+		name = ctr.Name()
+	}
+	return systemdgen.CreateSystemdUnitAsString(name, ctr.ID(), c.RestartPolicy, ctr.Config().StaticDir, timeout)
+}

pkg/adapter/containers_remote.go

@@ -956,3 +956,8 @@ func (r *LocalRuntime) Port(c *cliconfig.PortValues) ([]*Container, error) {
 	}
 	return containers, nil
 }
+
+// GenerateSystemd creates a systemd until for a container
+func (r *LocalRuntime) GenerateSystemd(c *cliconfig.GenerateSystemdValues) (string, error) {
+	return iopodman.GenerateSystemd().Call(r.Conn, c.InputArgs[0], c.RestartPolicy, int64(c.StopTimeout), c.Name)
+}

pkg/systemdgen/systemdgen.go

@@ -0,0 +1,43 @@
+package systemdgen
+
+import (
+	"fmt"
+	"path/filepath"
+
+	"github.com/pkg/errors"
+)
+
+var template = `[Unit]
+Description=%s Podman Container
+[Service]
+Restart=%s
+ExecStart=/usr/bin/podman start %s
+ExecStop=/usr/bin/podman stop -t %d %s
+KillMode=none
+Type=forking
+PIDFile=%s
+[Install]
+WantedBy=multi-user.target`
+
+var restartPolicies = []string{"no", "on-success", "on-failure", "on-abnormal", "on-watchdog", "on-abort", "always"}
+
+// ValidateRestartPolicy checks that the user-provided policy is valid
+func ValidateRestartPolicy(restart string) error {
+	for _, i := range restartPolicies {
+		if i == restart {
+			return nil
+		}
+	}
+	return errors.Errorf("%s is not a valid restart policy", restart)
+}
+
+// CreateSystemdUnitAsString takes variables to create a systemd unit file used to control
+// a libpod container
+func CreateSystemdUnitAsString(name, cid, restart, pidPath string, stopTimeout int) (string, error) {
+	if err := ValidateRestartPolicy(restart); err != nil {
+		return "", err
+	}
+	pidFile := filepath.Join(pidPath, fmt.Sprintf("%s.pid", cid))
+	unit := fmt.Sprintf(template, name, restart, name, stopTimeout, name, pidFile)
+	return unit, nil
+}

pkg/varlinkapi/generate.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"github.com/containers/libpod/cmd/podman/shared"
 	iopodman "github.com/containers/libpod/cmd/podman/varlink"
+	"github.com/containers/libpod/pkg/systemdgen"
 )
 
 // GenerateKube ...
@@ -28,3 +29,24 @@ func (i *LibpodAPI) GenerateKube(call iopodman.VarlinkCall, name string, service
 		Service: string(servB),
 	})
 }
+
+// GenerateSystemd ...
+func (i *LibpodAPI) GenerateSystemd(call iopodman.VarlinkCall, nameOrID, restart string, stopTimeout int64, useName bool) error {
+	ctr, err := i.Runtime.LookupContainer(nameOrID)
+	if err != nil {
+		return call.ReplyErrorOccurred(err.Error())
+	}
+	timeout := int(ctr.StopTimeout())
+	if stopTimeout >= 0 {
+		timeout = int(stopTimeout)
+	}
+	name := ctr.ID()
+	if useName {
+		name = ctr.Name()
+	}
+	unit, err := systemdgen.CreateSystemdUnitAsString(name, ctr.ID(), restart, ctr.Config().StaticDir, timeout)
+	if err != nil {
+		return call.ReplyErrorOccurred(err.Error())
+	}
+	return call.ReplyGenerateSystemd(unit)
+}

test/e2e/generate_systemd_test.go

@@ -0,0 +1,74 @@
+// +build !remoteclient
+
+package integration
+
+import (
+	. "github.com/containers/libpod/test/utils"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"os"
+)
+
+var _ = Describe("Podman generate systemd", func() {
+	var (
+		tempdir    string
+		err        error
+		podmanTest *PodmanTestIntegration
+	)
+
+	BeforeEach(func() {
+		tempdir, err = CreateTempDirInTempDir()
+		if err != nil {
+			os.Exit(1)
+		}
+		podmanTest = PodmanTestCreate(tempdir)
+		podmanTest.Setup()
+		podmanTest.RestoreAllArtifacts()
+	})
+
+	AfterEach(func() {
+		podmanTest.Cleanup()
+		f := CurrentGinkgoTestDescription()
+		processTestResult(f)
+
+	})
+
+	It("podman generate systemd on bogus container", func() {
+		session := podmanTest.Podman([]string{"generate", "systemd", "foobar"})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Not(Equal(0)))
+	})
+
+	It("podman generate systemd bad restart policy", func() {
+		session := podmanTest.Podman([]string{"generate", "systemd", "--restart-policy", "never", "foobar"})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Not(Equal(0)))
+	})
+
+	It("podman generate systemd bad timeout value", func() {
+		session := podmanTest.Podman([]string{"generate", "systemd", "--timeout", "-1", "foobar"})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Not(Equal(0)))
+	})
+
+	It("podman generate systemd", func() {
+		n := podmanTest.Podman([]string{"run", "--name", "nginx", "-dt", nginx})
+		n.WaitWithDefaultTimeout()
+		Expect(n.ExitCode()).To(Equal(0))
+
+		session := podmanTest.Podman([]string{"generate", "systemd", "nginx"})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Equal(0))
+	})
+
+	It("podman generate systemd with timeout", func() {
+		n := podmanTest.Podman([]string{"run", "--name", "nginx", "-dt", nginx})
+		n.WaitWithDefaultTimeout()
+		Expect(n.ExitCode()).To(Equal(0))
+
+		session := podmanTest.Podman([]string{"generate", "systemd", "--timeout", "5", "nginx"})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Equal(0))
+	})
+
+})