Support template unit files in podman generate systemd

Signed-off-by: Boaz Shuster <boaz.shuster.github@gmail.com>

cmd/podman/generate/systemd.go

@@ -21,6 +21,7 @@ import (
 const (
 	restartPolicyFlagName = "restart-policy"
 	timeFlagName          = "time"
+	newFlagName           = "new"
 )
 
 var (
@@ -53,10 +54,11 @@ func init() {
 	flags := systemdCmd.Flags()
 	flags.BoolVarP(&systemdOptions.Name, "name", "n", false, "Use container/pod names instead of IDs")
 	flags.BoolVarP(&files, "files", "f", false, "Generate .service files instead of printing to stdout")
+	flags.BoolVar(&systemdOptions.TemplateUnitFile, "template", false, "Make it a template file and use %i and %I specifiers. Working only for containers")
 
 	flags.UintVarP(&systemdTimeout, timeFlagName, "t", containerConfig.Engine.StopTimeout, "Stop timeout override")
 	_ = systemdCmd.RegisterFlagCompletionFunc(timeFlagName, completion.AutocompleteNone)
-	flags.BoolVarP(&systemdOptions.New, "new", "", false, "Create a new container or pod instead of starting an existing one")
+	flags.BoolVar(&systemdOptions.New, newFlagName, false, "Create a new container or pod instead of starting an existing one")
 	flags.BoolVarP(&systemdOptions.NoHeader, "no-header", "", false, "Skip header generation")
 
 	containerPrefixFlagName := "container-prefix"
@@ -93,6 +95,13 @@ func systemd(cmd *cobra.Command, args []string) error {
 		logrus.Warnln("The generated units should be placed on your remote system")
 	}
 
+	if cmd.Flags().Changed(newFlagName) && !systemdOptions.New && systemdOptions.TemplateUnitFile {
+		return errors.New("--template cannot be set with --new=false")
+	}
+	if !systemdOptions.New && systemdOptions.TemplateUnitFile {
+		systemdOptions.New = true
+	}
+
 	reports, err := registry.ContainerEngine().GenerateSystemd(registry.GetContext(), args[0], systemdOptions)
 	if err != nil {
 		return err

docs/source/markdown/podman-generate-systemd.1.md

@@ -59,6 +59,12 @@ Set the systemd unit name prefix for pods. The default is *pod*.
 
 Set the systemd unit name separator between the name/id of a container/pod and the prefix. The default is *-*.
 
+#### **--template**
+
+Add template specifiers to run multiple services from the systemd unit file.
+
+Note that if `--new` was not set to true, it is set to true by default. However, if `--new` is set to `false` explicitly the command will fail.
+
 ## EXAMPLES
 
 ### Generate and print a systemd unit file for a container

pkg/api/handlers/libpod/generate.go

@@ -20,6 +20,7 @@ func GenerateSystemd(w http.ResponseWriter, r *http.Request) {
 		Name             bool    `schema:"useName"`
 		New              bool    `schema:"new"`
 		NoHeader         bool    `schema:"noHeader"`
+		TemplateUnitFile bool    `schema:"templateUnitFile"`
 		RestartPolicy    *string `schema:"restartPolicy"`
 		StopTimeout      uint    `schema:"stopTimeout"`
 		ContainerPrefix  string  `schema:"containerPrefix"`
@@ -43,6 +44,7 @@ func GenerateSystemd(w http.ResponseWriter, r *http.Request) {
 		Name:             query.Name,
 		New:              query.New,
 		NoHeader:         query.NoHeader,
+		TemplateUnitFile: query.TemplateUnitFile,
 		RestartPolicy:    query.RestartPolicy,
 		StopTimeout:      &query.StopTimeout,
 		ContainerPrefix:  query.ContainerPrefix,

pkg/bindings/generate/types.go

@@ -16,6 +16,8 @@ type SystemdOptions struct {
 	New *bool
 	// NoHeader - Removes autogenerated by Podman and timestamp if set to true
 	NoHeader *bool
+	// TemplateUnitFile - Create a template unit file that uses the identity specifiers
+	TemplateUnitFile *bool
 	// RestartPolicy - systemd restart policy.
 	RestartPolicy *string
 	// StopTimeout - time when stopping the container.

pkg/bindings/generate/types_systemd_options.go

@@ -62,6 +62,21 @@ func (o *SystemdOptions) GetNoHeader() bool {
 	return *o.NoHeader
 }
 
+// WithTemplateUnitFile set field TemplateUnitFile to given value
+func (o *SystemdOptions) WithTemplateUnitFile(value bool) *SystemdOptions {
+	o.TemplateUnitFile = &value
+	return o
+}
+
+// GetTemplateUnitFile returns value of field TemplateUnitFile
+func (o *SystemdOptions) GetTemplateUnitFile() bool {
+	if o.TemplateUnitFile == nil {
+		var z bool
+		return z
+	}
+	return *o.TemplateUnitFile
+}
+
 // WithRestartPolicy set field RestartPolicy to given value
 func (o *SystemdOptions) WithRestartPolicy(value string) *SystemdOptions {
 	o.RestartPolicy = &value

pkg/domain/entities/generate.go

@@ -20,6 +20,8 @@ type GenerateSystemdOptions struct {
 	Separator string
 	// NoHeader - skip header generation
 	NoHeader bool
+	// TemplateUnitFile - make use of %i and %I to differentiate between the different instances of the unit
+	TemplateUnitFile bool
 }
 
 // GenerateSystemdReport

pkg/domain/infra/tunnel/generate.go

@@ -8,7 +8,7 @@ import (
 )
 
 func (ic *ContainerEngine) GenerateSystemd(ctx context.Context, nameOrID string, opts entities.GenerateSystemdOptions) (*entities.GenerateSystemdReport, error) {
-	options := new(generate.SystemdOptions).WithUseName(opts.Name).WithContainerPrefix(opts.ContainerPrefix).WithNew(opts.New).WithNoHeader(opts.NoHeader)
+	options := new(generate.SystemdOptions).WithUseName(opts.Name).WithContainerPrefix(opts.ContainerPrefix).WithNew(opts.New).WithNoHeader(opts.NoHeader).WithTemplateUnitFile(opts.TemplateUnitFile)
 	options.WithPodPrefix(opts.PodPrefix).WithSeparator(opts.Separator)
 	if opts.RestartPolicy != nil {
 		options.WithRestartPolicy(*opts.RestartPolicy)

pkg/systemd/generate/common.go

@@ -23,7 +23,7 @@ func validateRestartPolicy(restart string) error {
 	return errors.Errorf("%s is not a valid restart policy", restart)
 }
 
-const headerTemplate = `# {{{{.ServiceName}}}}.service
+const headerTemplate = `# {{{{.ServiceName}}}}{{{{- if (eq .IdentifySpecifier true) }}}}@{{{{- end}}}}.service
 {{{{- if (eq .GenerateNoHeader false) }}}}
 # autogenerated by Podman {{{{.PodmanVersion}}}}
 {{{{- if .TimeStamp}}}}
@@ -32,7 +32,7 @@ const headerTemplate = `# {{{{.ServiceName}}}}.service
 {{{{- end}}}}
 
 [Unit]
-Description=Podman {{{{.ServiceName}}}}.service
+Description=Podman {{{{.ServiceName}}}}.service{{{{- if (eq .IdentifySpecifier true) }}}} for %I{{{{- end}}}}
 Documentation=man:podman-generate-systemd(1)
 Wants=network-online.target
 After=network-online.target

pkg/systemd/generate/containers.go

@@ -90,6 +90,8 @@ type containerInfo struct {
 	// Location of the RunRoot for the container.  Required for ensuring the tmpfs
 	// or volume exists and is mounted when coming online at boot.
 	RunRoot string
+	// Add %i and %I to description and execute parts
+	IdentifySpecifier bool
 }
 
 const containerTemplate = headerTemplate + `
@@ -99,7 +101,7 @@ After={{{{- range $index, $value := .BoundToServices -}}}}{{{{if $index}}}} {{{{
 {{{{- end}}}}
 
 [Service]
-Environment={{{{.EnvVariable}}}}=%n
+Environment={{{{.EnvVariable}}}}=%n{{{{- if (eq .IdentifySpecifier true) }}}}-%i{{{{- end}}}}
 {{{{- if .ExtraEnvs}}}}
 Environment={{{{- range $index, $value := .ExtraEnvs -}}}}{{{{if $index}}}} {{{{end}}}}{{{{ $value }}}}{{{{end}}}}
 {{{{- end}}}}
@@ -273,7 +275,6 @@ func executeContainerTemplate(info *containerInfo, options entities.GenerateSyst
 			"--rm",
 		)
 		remainingCmd := info.CreateCommand[index:]
-
 		// Presence check for certain flags/options.
 		fs := pflag.NewFlagSet("args", pflag.ContinueOnError)
 		fs.ParseErrorsWhitelist.UnknownFlags = true
@@ -389,6 +390,32 @@ func executeContainerTemplate(info *containerInfo, options entities.GenerateSyst
 
 		startCommand = append(startCommand, remainingCmd...)
 		startCommand = escapeSystemdArguments(startCommand)
+		if options.TemplateUnitFile {
+			info.IdentifySpecifier = true
+			runIx := -1
+			nameIx := -1
+			for argIx, arg := range startCommand {
+				if arg == "run" {
+					runIx = argIx
+					continue
+				}
+				if arg == "--name" {
+					nameIx = argIx + 1
+					break
+				}
+				if strings.HasPrefix(arg, "--name=") {
+					nameIx = argIx
+					break
+				}
+			}
+			if nameIx == -1 {
+				startCommand = append(startCommand[:runIx+1], startCommand[runIx:]...)
+				startCommand[runIx+1] = fmt.Sprintf("--name=%s-%%i", info.ServiceName)
+				fmt.Println(startCommand)
+			} else {
+				startCommand[nameIx] = fmt.Sprintf("%s-%%i", startCommand[nameIx])
+			}
+		}
 		info.ExecStart = strings.Join(startCommand, " ")
 	}
 

pkg/systemd/generate/pods.go

@@ -79,6 +79,8 @@ type podInfo struct {
 	// Location of the RunRoot for the pod.  Required for ensuring the tmpfs
 	// or volume exists and is mounted when coming online at boot.
 	RunRoot string
+	// Add %i and %I to description and execute parts - this should not be used
+	IdentifySpecifier bool
 }
 
 const podTemplate = headerTemplate + `Requires={{{{- range $index, $value := .RequiredServices -}}}}{{{{if $index}}}} {{{{end}}}}{{{{ $value }}}}.service{{{{end}}}}
@@ -108,6 +110,9 @@ WantedBy=multi-user.target default.target
 // Based on the options, the return value might be the content of all units or
 // the files they been written to.
 func PodUnits(pod *libpod.Pod, options entities.GenerateSystemdOptions) (map[string]string, error) {
+	if options.TemplateUnitFile {
+		return nil, errors.New("--template is not supported for pods")
+	}
 	// Error out if the pod has no infra container, which we require to be the
 	// main service.
 	if !pod.HasInfraContainer() {

test/system/250-systemd.bats

@@ -201,4 +201,33 @@ LISTEN_FDNAMES=listen_fdnames" "LISTEN Environment passed: $context"
     check_listen_env "$stdenv" "podman start"
 }
 
+@test "podman generate - systemd template" {
+    cname=$(random_string)
+    run_podman run -dt --name $cname $IMAGE top
+
+    run_podman generate systemd --template -n $cname
+    is "$output" ".*%I.*" "%I indentifiers in template"
+    is "$output" ".*%i.*" "%i indentifiers in template"
+}
+
+@test "podman generate - systemd template no support for pod" {
+    cname=$(random_string)
+    podname=$(random_string)
+    run_podman pod create --name $podname
+    run_podman run --pod $podname -dt --name $cname $IMAGE top
+
+    run_podman 125 generate systemd --new --template -n $podname
+    is "$output" ".*--template is not supported for pods.*" "Error message contains 'not supported'"
+
+    run_podman rm -f $cname
+    run_podman pod rm -f $podname
+}
+
+@test "podman generate - systemd template only used on --new" {
+    cname=$(random_string)
+    run_podman create --name $cname $IMAGE top
+    run_podman 125 generate systemd --new=false --template -n $cname
+    is "$output" ".*--template cannot be set" "Error message should be '--template requires --new'"
+}
+
 # vim: filetype=sh