Merge pull request #3800 from vrothberg/generate-pod

generate systemd pod

1 files changed, 118 insertions, 29 deletions

diff --git a/pkg/systemdgen/systemdgen.go b/pkg/systemdgen/systemdgen.go
index 06c5ebde5..09d3c6fd5 100644
--- a/pkg/systemdgen/systemdgen.go
+++ b/pkg/systemdgen/systemdgen.go
@@ -1,29 +1,59 @@
 package systemdgen
 
 import (
+	"bytes"
 	"fmt"
+	"io/ioutil"
 	"os"
+	"path/filepath"
+	"sort"
+	"text/template"
+	"time"
 
+	"github.com/containers/libpod/version"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
-var template = `[Unit]
-Description=%s Podman Container
-[Service]
-Restart=%s
-ExecStart=%s start %s
-ExecStop=%s stop -t %d %s
-KillMode=none
-Type=forking
-PIDFile=%s
-[Install]
-WantedBy=multi-user.target`
+// ContainerInfo contains data required for generating a container's systemd
+// unit file.
+type ContainerInfo struct {
+	// ServiceName of the systemd service.
+	ServiceName string
+	// Name or ID of the container.
+	ContainerName string
+	// InfraContainer of the pod.
+	InfraContainer string
+	// StopTimeout sets the timeout Podman waits before killing the container
+	// during service stop.
+	StopTimeout int
+	// RestartPolicy of the systemd unit (e.g., no, on-failure, always).
+	RestartPolicy string
+	// PIDFile of the service. Required for forking services. Must point to the
+	// PID of the associated conmon process.
+	PIDFile string
+	// GenerateTimestamp, if set the generated unit file has a time stamp.
+	GenerateTimestamp bool
+	// BoundToServices are the services this service binds to.  Note that this
+	// service runs after them.
+	BoundToServices []string
+	// RequiredServices are services this service requires. Note that this
+	// service runs before them.
+	RequiredServices []string
+	// PodmanVersion for the header. Will be set internally. Will be auto-filled
+	// if left empty.
+	PodmanVersion string
+	// Executable is the path to the podman executable. Will be auto-filled if
+	// left empty.
+	Executable string
+	// TimeStamp at the time of creating the unit file. Will be set internally.
+	TimeStamp string
+}
 
 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 {
+// validateRestartPolicy checks that the user-provided policy is valid.
+func validateRestartPolicy(restart string) error {
 	for _, i := range restartPolicies {
 		if i == restart {
 			return nil
@@ -32,28 +62,87 @@ func ValidateRestartPolicy(restart string) error {
 	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, pidFile string, stopTimeout int) (string, error) {
-	podmanExe := getPodmanExecutable()
-	return createSystemdUnitAsString(podmanExe, name, cid, restart, pidFile, stopTimeout)
-}
+const containerTemplate = `# {{.ServiceName}}.service
+# autogenerated by Podman {{.PodmanVersion}}
+{{- if .TimeStamp}}
+# {{.TimeStamp}}
+{{- end}}
+
+[Unit]
+Description=Podman {{.ServiceName}}.service
+Documentation=man:podman-generate-systemd(1)
+{{- if .BoundToServices}}
+RefuseManualStart=yes
+RefuseManualStop=yes
+BindsTo={{- range $index, $value := .BoundToServices -}}{{if $index}} {{end}}{{ $value }}.service{{end}}
+After={{- range $index, $value := .BoundToServices -}}{{if $index}} {{end}}{{ $value }}.service{{end}}
+{{- end}}
+{{- if .RequiredServices}}
+Requires={{- range $index, $value := .RequiredServices -}}{{if $index}} {{end}}{{ $value }}.service{{end}}
+Before={{- range $index, $value := .RequiredServices -}}{{if $index}} {{end}}{{ $value }}.service{{end}}
+{{- end}}
+
+[Service]
+Restart={{.RestartPolicy}}
+ExecStart={{.Executable}} start {{.ContainerName}}
+ExecStop={{.Executable}} stop {{if (ge .StopTimeout 0)}}-t {{.StopTimeout}}{{end}} {{.ContainerName}}
+KillMode=none
+Type=forking
+PIDFile={{.PIDFile}}
+
+[Install]
+WantedBy=multi-user.target`
 
-func createSystemdUnitAsString(exe, name, cid, restart, pidFile string, stopTimeout int) (string, error) {
-	if err := ValidateRestartPolicy(restart); err != nil {
+// CreateContainerSystemdUnit creates a systemd unit file for a container.
+func CreateContainerSystemdUnit(info *ContainerInfo, generateFiles bool) (string, error) {
+	if err := validateRestartPolicy(info.RestartPolicy); err != nil {
 		return "", err
 	}
 
-	unit := fmt.Sprintf(template, name, restart, exe, name, exe, stopTimeout, name, pidFile)
-	return unit, nil
-}
+	// Make sure the executable is set.
+	if info.Executable == "" {
+		executable, err := os.Executable()
+		if err != nil {
+			executable = "/usr/bin/podman"
+			logrus.Warnf("Could not obtain podman executable location, using default %s", executable)
+		}
+		info.Executable = executable
+	}
+
+	if info.PodmanVersion == "" {
+		info.PodmanVersion = version.Version
+	}
+	if info.GenerateTimestamp {
+		info.TimeStamp = fmt.Sprintf("%v", time.Now().Format(time.UnixDate))
+	}
 
-func getPodmanExecutable() string {
-	podmanExe, err := os.Executable()
+	// Sort the slices to assure a deterministic output.
+	sort.Strings(info.RequiredServices)
+	sort.Strings(info.BoundToServices)
+
+	// Generate the template and compile it.
+	templ, err := template.New("systemd_service_file").Parse(containerTemplate)
 	if err != nil {
-		podmanExe = "/usr/bin/podman"
-		logrus.Warnf("Could not obtain podman executable location, using default %s", podmanExe)
+		return "", errors.Wrap(err, "error parsing systemd service template")
 	}
 
-	return podmanExe
+	var buf bytes.Buffer
+	if err := templ.Execute(&buf, info); err != nil {
+		return "", err
+	}
+
+	if !generateFiles {
+		return buf.String(), nil
+	}
+
+	buf.WriteByte('\n')
+	cwd, err := os.Getwd()
+	if err != nil {
+		return "", errors.Wrap(err, "error getting current working directory")
+	}
+	path := filepath.Join(cwd, fmt.Sprintf("%s.service", info.ServiceName))
+	if err := ioutil.WriteFile(path, buf.Bytes(), 0644); err != nil {
+		return "", errors.Wrap(err, "error generating systemd unit")
+	}
+	return path, nil
 }