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>

1 files changed, 43 insertions, 0 deletions

diff --git a/pkg/systemdgen/systemdgen.go b/pkg/systemdgen/systemdgen.go
new file mode 100644
index 000000000..3d1c31b5d
--- /dev/null
+++ b/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
+}