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>

4 files changed, 88 insertions, 0 deletions

diff --git a/pkg/adapter/containers.go b/pkg/adapter/containers.go
index eb90ab50e..d575bc9b0 100644
--- a/pkg/adapter/containers.go
+++ b/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)
+}
diff --git a/pkg/adapter/containers_remote.go b/pkg/adapter/containers_remote.go
index b7e353f71..201249fc3 100644
--- a/pkg/adapter/containers_remote.go
+++ b/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)
+}
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
+}
diff --git a/pkg/varlinkapi/generate.go b/pkg/varlinkapi/generate.go
index bc600c397..9dc20d582 100644
--- a/pkg/varlinkapi/generate.go
+++ b/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)
+}