generate systemd: refactor

Refactor the systemd-unit generation code and move all the logic into
`pkg/systemd/generate`.  The code was already hard to maintain but I
found it impossible to wire the `--new` logic for pods in all the chaos.

The code refactoring in this commit will make maintaining the code
easier and should make it easier to extend as well.  Further changes and
refactorings may still be needed but they will easier.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

6 files changed, 347 insertions, 282 deletions

diff --git a/libpod/pod.go b/libpod/pod.go
index db87e60f2..f53290876 100644
--- a/libpod/pod.go
+++ b/libpod/pod.go
@@ -257,6 +257,20 @@ func (p *Pod) InfraContainerID() (string, error) {
 	return p.state.InfraContainerID, nil
 }
 
+// InfraContainer returns the infra container.
+func (p *Pod) InfraContainer() (*Container, error) {
+	if !p.HasInfraContainer() {
+		return nil, errors.New("pod has no infra container")
+	}
+
+	id, err := p.InfraContainerID()
+	if err != nil {
+		return nil, err
+	}
+
+	return p.runtime.state.Container(id)
+}
+
 // TODO add pod batching
 // Lock pod to avoid lock contention
 // Store and lock all containers (no RemoveContainer in batch guarantees cache will not become stale)
diff --git a/pkg/domain/infra/abi/generate.go b/pkg/domain/infra/abi/generate.go
index 08cb87287..fa0cfb389 100644
--- a/pkg/domain/infra/abi/generate.go
+++ b/pkg/domain/infra/abi/generate.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"strings"
 
 	"github.com/containers/libpod/libpod"
 	"github.com/containers/libpod/libpod/define"
@@ -16,165 +15,28 @@ import (
 )
 
 func (ic *ContainerEngine) GenerateSystemd(ctx context.Context, nameOrID string, options entities.GenerateSystemdOptions) (*entities.GenerateSystemdReport, error) {
-	opts := generate.Options{
-		Files: options.Files,
-		New:   options.New,
-	}
-
 	// First assume it's a container.
-	if info, found, err := ic.generateSystemdgenContainerInfo(nameOrID, nil, options); found && err != nil {
-		return nil, err
-	} else if found && err == nil {
-		output, err := generate.CreateContainerSystemdUnit(info, opts)
-		if err != nil {
-			return nil, err
+	ctr, err := ic.Libpod.LookupContainer(nameOrID)
+	if err == nil {
+		// Generate the unit for the container.
+		s, err := generate.ContainerUnit(ctr, options)
+		if err == nil {
+			return &entities.GenerateSystemdReport{Output: s}, nil
 		}
-		return &entities.GenerateSystemdReport{Output: output}, nil
-	}
-
-	// --new does not support pods.
-	if options.New {
-		return nil, errors.Errorf("error generating systemd unit files: cannot generate generic files for a pod")
 	}
 
-	// We're either having a pod or garbage.
+	// If it's not a container, we either have a pod or garbage.
 	pod, err := ic.Libpod.LookupPod(nameOrID)
 	if err != nil {
 		return nil, errors.Errorf("%q does not refer to a container or pod", nameOrID)
 	}
 
-	// Error out if the pod has no infra container, which we require to be the
-	// main service.
-	if !pod.HasInfraContainer() {
-		return nil, fmt.Errorf("error generating systemd unit files: Pod %q has no infra container", pod.Name())
-	}
-
-	// Generate a systemdgen.ContainerInfo for the infra container. This
-	// ContainerInfo acts as the main service of the pod.
-	infraID, err := pod.InfraContainerID()
-	if err != nil {
-		return nil, nil
-	}
-	podInfo, _, err := ic.generateSystemdgenContainerInfo(infraID, pod, options)
+	// Generate the units for the pod and all its containers.
+	s, err := generate.PodUnits(pod, options)
 	if err != nil {
 		return nil, err
 	}
-
-	// Compute the container-dependency graph for the Pod.
-	containers, err := pod.AllContainers()
-	if err != nil {
-		return nil, err
-	}
-	if len(containers) == 0 {
-		return nil, fmt.Errorf("error generating systemd unit files: Pod %q has no containers", pod.Name())
-	}
-	graph, err := libpod.BuildContainerGraph(containers)
-	if err != nil {
-		return nil, err
-	}
-
-	// Traverse the dependency graph and create systemdgen.ContainerInfo's for
-	// each container.
-	containerInfos := []*generate.ContainerInfo{podInfo}
-	for ctr, dependencies := range graph.DependencyMap() {
-		// Skip the infra container as we already generated it.
-		if ctr.ID() == infraID {
-			continue
-		}
-		ctrInfo, _, err := ic.generateSystemdgenContainerInfo(ctr.ID(), nil, options)
-		if err != nil {
-			return nil, err
-		}
-		// Now add the container's dependencies and at the container as a
-		// required service of the infra container.
-		for _, dep := range dependencies {
-			if dep.ID() == infraID {
-				ctrInfo.BoundToServices = append(ctrInfo.BoundToServices, podInfo.ServiceName)
-			} else {
-				_, serviceName := generateServiceName(dep, nil, options)
-				ctrInfo.BoundToServices = append(ctrInfo.BoundToServices, serviceName)
-			}
-		}
-		podInfo.RequiredServices = append(podInfo.RequiredServices, ctrInfo.ServiceName)
-		containerInfos = append(containerInfos, ctrInfo)
-	}
-
-	// Now generate the systemd service for all containers.
-	builder := strings.Builder{}
-	for i, info := range containerInfos {
-		if i > 0 {
-			builder.WriteByte('\n')
-		}
-		out, err := generate.CreateContainerSystemdUnit(info, opts)
-		if err != nil {
-			return nil, err
-		}
-		builder.WriteString(out)
-	}
-
-	return &entities.GenerateSystemdReport{Output: builder.String()}, nil
-}
-
-// generateSystemdgenContainerInfo is a helper to generate a
-// systemdgen.ContainerInfo for `GenerateSystemd`.
-func (ic *ContainerEngine) generateSystemdgenContainerInfo(nameOrID string, pod *libpod.Pod, options entities.GenerateSystemdOptions) (*generate.ContainerInfo, bool, error) {
-	ctr, err := ic.Libpod.LookupContainer(nameOrID)
-	if err != nil {
-		return nil, false, err
-	}
-
-	timeout := ctr.StopTimeout()
-	if options.StopTimeout != nil {
-		timeout = *options.StopTimeout
-	}
-
-	config := ctr.Config()
-	conmonPidFile := config.ConmonPidFile
-	if conmonPidFile == "" {
-		return nil, true, errors.Errorf("conmon PID file path is empty, try to recreate the container with --conmon-pidfile flag")
-	}
-
-	createCommand := []string{}
-	if config.CreateCommand != nil {
-		createCommand = config.CreateCommand
-	} else if options.New {
-		return nil, true, errors.Errorf("cannot use --new on container %q: no create command found", nameOrID)
-	}
-
-	name, serviceName := generateServiceName(ctr, pod, options)
-	info := &generate.ContainerInfo{
-		ServiceName:       serviceName,
-		ContainerName:     name,
-		RestartPolicy:     options.RestartPolicy,
-		PIDFile:           conmonPidFile,
-		StopTimeout:       timeout,
-		GenerateTimestamp: true,
-		CreateCommand:     createCommand,
-	}
-
-	return info, true, nil
-}
-
-// generateServiceName generates the container name and the service name for systemd service.
-func generateServiceName(ctr *libpod.Container, pod *libpod.Pod, options entities.GenerateSystemdOptions) (string, string) {
-	var kind, name, ctrName string
-	if pod == nil {
-		kind = options.ContainerPrefix //defaults to container
-		name = ctr.ID()
-		if options.Name {
-			name = ctr.Name()
-		}
-		ctrName = name
-	} else {
-		kind = options.PodPrefix //defaults to pod
-		name = pod.ID()
-		ctrName = ctr.ID()
-		if options.Name {
-			name = pod.Name()
-			ctrName = ctr.Name()
-		}
-	}
-	return ctrName, fmt.Sprintf("%s%s%s", kind, options.Separator, name)
+	return &entities.GenerateSystemdReport{Output: s}, nil
 }
 
 func (ic *ContainerEngine) GenerateKube(ctx context.Context, nameOrID string, options entities.GenerateKubeOptions) (*entities.GenerateKubeReport, error) {
diff --git a/pkg/systemd/generate/common.go b/pkg/systemd/generate/common.go
new file mode 100644
index 000000000..e809b4837
--- /dev/null
+++ b/pkg/systemd/generate/common.go
@@ -0,0 +1,36 @@
+package generate
+
+import (
+	"github.com/pkg/errors"
+)
+
+// EnvVariable "PODMAN_SYSTEMD_UNIT" is set in all generated systemd units and
+// is set to the unit's (unique) name.
+const EnvVariable = "PODMAN_SYSTEMD_UNIT"
+
+// restartPolicies includes all valid restart policies to be used in a unit
+// file.
+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)
+}
+
+const headerTemplate = `# {{.ServiceName}}.service
+# autogenerated by Podman {{.PodmanVersion}}
+{{- if .TimeStamp}}
+# {{.TimeStamp}}
+{{- end}}
+
+[Unit]
+Description=Podman {{.ServiceName}}.service
+Documentation=man:podman-generate-systemd(1)
+Wants=network.target
+After=network-online.target
+`
diff --git a/pkg/systemd/generate/containers.go b/pkg/systemd/generate/containers.go
index fb0ea5cf9..f316d4452 100644
--- a/pkg/systemd/generate/containers.go
+++ b/pkg/systemd/generate/containers.go
@@ -11,22 +11,20 @@ import (
 	"text/template"
 	"time"
 
+	"github.com/containers/libpod/libpod"
+	"github.com/containers/libpod/pkg/domain/entities"
 	"github.com/containers/libpod/version"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
-// EnvVariable "PODMAN_SYSTEMD_UNIT" is set in all generated systemd units and
-// is set to the unit's (unique) name.
-const EnvVariable = "PODMAN_SYSTEMD_UNIT"
-
-// ContainerInfo contains data required for generating a container's systemd
+// containerInfo contains data required for generating a container's systemd
 // unit file.
-type ContainerInfo struct {
+type containerInfo struct {
 	// ServiceName of the systemd service.
 	ServiceName string
 	// Name or ID of the container.
-	ContainerName string
+	ContainerNameOrID string
 	// StopTimeout sets the timeout Podman waits before killing the container
 	// during service stop.
 	StopTimeout uint
@@ -63,29 +61,7 @@ type ContainerInfo struct {
 	EnvVariable 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 {
-	for _, i := range restartPolicies {
-		if i == restart {
-			return nil
-		}
-	}
-	return errors.Errorf("%s is not a valid restart policy", restart)
-}
-
-const containerTemplate = `# {{.ServiceName}}.service
-# autogenerated by Podman {{.PodmanVersion}}
-{{- if .TimeStamp}}
-# {{.TimeStamp}}
-{{- end}}
-
-[Unit]
-Description=Podman {{.ServiceName}}.service
-Documentation=man:podman-generate-systemd(1)
-Wants=network.target
-After=network-online.target
+const containerTemplate = headerTemplate + `
 {{- if .BoundToServices}}
 RefuseManualStart=yes
 RefuseManualStop=yes
@@ -107,8 +83,8 @@ ExecStop={{.Executable}} stop --ignore --cidfile %t/%n-ctr-id {{if (ge .StopTime
 ExecStopPost={{.Executable}} rm --ignore -f --cidfile %t/%n-ctr-id
 PIDFile=%t/%n-pid
 {{- else}}
-ExecStart={{.Executable}} start {{.ContainerName}}
-ExecStop={{.Executable}} stop {{if (ge .StopTimeout 0)}}-t {{.StopTimeout}}{{end}} {{.ContainerName}}
+ExecStart={{.Executable}} start {{.ContainerNameOrID}}
+ExecStop={{.Executable}} stop {{if (ge .StopTimeout 0)}}-t {{.StopTimeout}}{{end}} {{.ContainerNameOrID}}
 PIDFile={{.PIDFile}}
 {{- end}}
 KillMode=none
@@ -117,18 +93,19 @@ Type=forking
 [Install]
 WantedBy=multi-user.target default.target`
 
-// Options include different options to control the unit file generation.
-type Options struct {
-	// When set, generate service files in the current working directory and
-	// return the paths to these files instead of returning all contents in one
-	// big string.
-	Files bool
-	// New controls if a new container is created or if an existing one is started.
-	New bool
+// ContainerUnit generates a systemd unit for the specified container.  Based
+// on the options, the return value might be the entire unit or a file it has
+// been written to.
+func ContainerUnit(ctr *libpod.Container, options entities.GenerateSystemdOptions) (string, error) {
+	info, err := generateContainerInfo(ctr, options)
+	if err != nil {
+		return "", err
+	}
+	return createContainerSystemdUnit(info, options)
 }
 
-// CreateContainerSystemdUnit creates a systemd unit file for a container.
-func CreateContainerSystemdUnit(info *ContainerInfo, opts Options) (string, error) {
+// createContainerSystemdUnit creates a systemd unit file for a container.
+func createContainerSystemdUnit(info *containerInfo, options entities.GenerateSystemdOptions) (string, error) {
 	if err := validateRestartPolicy(info.RestartPolicy); err != nil {
 		return "", err
 	}
@@ -152,7 +129,7 @@ func CreateContainerSystemdUnit(info *ContainerInfo, opts Options) (string, erro
 	// been created via a Python script, which would certainly yield an
 	// invalid `info.CreateCommand`.  Hence, we're doing a best effort unit
 	// generation and don't try aiming at completeness.
-	if opts.New {
+	if options.New {
 		// The create command must at least have three arguments:
 		// 	/usr/bin/podman run $IMAGE
 		index := 2
@@ -218,7 +195,7 @@ func CreateContainerSystemdUnit(info *ContainerInfo, opts Options) (string, erro
 		return "", err
 	}
 
-	if !opts.Files {
+	if !options.Files {
 		return buf.String(), nil
 	}
 
@@ -233,3 +210,47 @@ func CreateContainerSystemdUnit(info *ContainerInfo, opts Options) (string, erro
 	}
 	return path, nil
 }
+
+func generateContainerInfo(ctr *libpod.Container, options entities.GenerateSystemdOptions) (*containerInfo, error) {
+	timeout := ctr.StopTimeout()
+	if options.StopTimeout != nil {
+		timeout = *options.StopTimeout
+	}
+
+	config := ctr.Config()
+	conmonPidFile := config.ConmonPidFile
+	if conmonPidFile == "" {
+		return nil, errors.Errorf("conmon PID file path is empty, try to recreate the container with --conmon-pidfile flag")
+	}
+
+	createCommand := []string{}
+	if config.CreateCommand != nil {
+		createCommand = config.CreateCommand
+	} else if options.New {
+		return nil, errors.Errorf("cannot use --new on container %q: no create command found", ctr.ID())
+	}
+
+	nameOrID, serviceName := containerServiceName(ctr, options)
+
+	info := containerInfo{
+		ServiceName:       serviceName,
+		ContainerNameOrID: nameOrID,
+		RestartPolicy:     options.RestartPolicy,
+		PIDFile:           conmonPidFile,
+		StopTimeout:       timeout,
+		GenerateTimestamp: true,
+		CreateCommand:     createCommand,
+	}
+	return &info, nil
+}
+
+// containerServiceName returns the nameOrID and the service name of the
+// container.
+func containerServiceName(ctr *libpod.Container, options entities.GenerateSystemdOptions) (string, string) {
+	nameOrID := ctr.ID()
+	if options.Name {
+		nameOrID = ctr.Name()
+	}
+	serviceName := fmt.Sprintf("%s%s%s", options.ContainerPrefix, options.Separator, nameOrID)
+	return nameOrID, serviceName
+}
diff --git a/pkg/systemd/generate/containers_test.go b/pkg/systemd/generate/generate_test.go
index 9da261a69..11cabb463 100644
--- a/pkg/systemd/generate/containers_test.go
+++ b/pkg/systemd/generate/generate_test.go
@@ -2,31 +2,33 @@ package generate
 
 import (
 	"testing"
+
+	"github.com/containers/libpod/pkg/domain/entities"
 )
 
 func TestValidateRestartPolicy(t *testing.T) {
-	type ContainerInfo struct {
+	type containerInfo struct {
 		restart string
 	}
 	tests := []struct {
 		name          string
-		ContainerInfo ContainerInfo
+		containerInfo containerInfo
 		wantErr       bool
 	}{
-		{"good-on", ContainerInfo{restart: "no"}, false},
-		{"good-on-success", ContainerInfo{restart: "on-success"}, false},
-		{"good-on-failure", ContainerInfo{restart: "on-failure"}, false},
-		{"good-on-abnormal", ContainerInfo{restart: "on-abnormal"}, false},
-		{"good-on-watchdog", ContainerInfo{restart: "on-watchdog"}, false},
-		{"good-on-abort", ContainerInfo{restart: "on-abort"}, false},
-		{"good-always", ContainerInfo{restart: "always"}, false},
-		{"fail", ContainerInfo{restart: "foobar"}, true},
-		{"failblank", ContainerInfo{restart: ""}, true},
+		{"good-on", containerInfo{restart: "no"}, false},
+		{"good-on-success", containerInfo{restart: "on-success"}, false},
+		{"good-on-failure", containerInfo{restart: "on-failure"}, false},
+		{"good-on-abnormal", containerInfo{restart: "on-abnormal"}, false},
+		{"good-on-watchdog", containerInfo{restart: "on-watchdog"}, false},
+		{"good-on-abort", containerInfo{restart: "on-abort"}, false},
+		{"good-always", containerInfo{restart: "always"}, false},
+		{"fail", containerInfo{restart: "foobar"}, true},
+		{"failblank", containerInfo{restart: ""}, true},
 	}
 	for _, tt := range tests {
 		test := tt
 		t.Run(tt.name, func(t *testing.T) {
-			if err := validateRestartPolicy(test.ContainerInfo.restart); (err != nil) != test.wantErr {
+			if err := validateRestartPolicy(test.containerInfo.restart); (err != nil) != test.wantErr {
 				t.Errorf("ValidateRestartPolicy() error = %v, wantErr %v", err, test.wantErr)
 			}
 		})
@@ -195,67 +197,67 @@ WantedBy=multi-user.target default.target`
 
 	tests := []struct {
 		name    string
-		info    ContainerInfo
+		info    containerInfo
 		want    string
 		wantErr bool
 	}{
 
 		{"good with id",
-			ContainerInfo{
-				Executable:    "/usr/bin/podman",
-				ServiceName:   "container-639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
-				ContainerName: "639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
-				RestartPolicy: "always",
-				PIDFile:       "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
-				StopTimeout:   10,
-				PodmanVersion: "CI",
+			containerInfo{
+				Executable:        "/usr/bin/podman",
+				ServiceName:       "container-639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
+				ContainerNameOrID: "639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
+				RestartPolicy:     "always",
+				PIDFile:           "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
+				StopTimeout:       10,
+				PodmanVersion:     "CI",
 			},
 			goodID,
 			false,
 		},
 		{"good with name",
-			ContainerInfo{
-				Executable:    "/usr/bin/podman",
-				ServiceName:   "container-foobar",
-				ContainerName: "foobar",
-				RestartPolicy: "always",
-				PIDFile:       "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
-				StopTimeout:   10,
-				PodmanVersion: "CI",
+			containerInfo{
+				Executable:        "/usr/bin/podman",
+				ServiceName:       "container-foobar",
+				ContainerNameOrID: "foobar",
+				RestartPolicy:     "always",
+				PIDFile:           "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
+				StopTimeout:       10,
+				PodmanVersion:     "CI",
 			},
 			goodName,
 			false,
 		},
 		{"good with name and bound to",
-			ContainerInfo{
-				Executable:      "/usr/bin/podman",
-				ServiceName:     "container-foobar",
-				ContainerName:   "foobar",
-				RestartPolicy:   "always",
-				PIDFile:         "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
-				StopTimeout:     10,
-				PodmanVersion:   "CI",
-				BoundToServices: []string{"pod", "a", "b", "c"},
+			containerInfo{
+				Executable:        "/usr/bin/podman",
+				ServiceName:       "container-foobar",
+				ContainerNameOrID: "foobar",
+				RestartPolicy:     "always",
+				PIDFile:           "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
+				StopTimeout:       10,
+				PodmanVersion:     "CI",
+				BoundToServices:   []string{"pod", "a", "b", "c"},
 			},
 			goodNameBoundTo,
 			false,
 		},
 		{"pod",
-			ContainerInfo{
-				Executable:       "/usr/bin/podman",
-				ServiceName:      "pod-123abc",
-				ContainerName:    "jadda-jadda-infra",
-				RestartPolicy:    "always",
-				PIDFile:          "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
-				StopTimeout:      10,
-				PodmanVersion:    "CI",
-				RequiredServices: []string{"container-1", "container-2"},
+			containerInfo{
+				Executable:        "/usr/bin/podman",
+				ServiceName:       "pod-123abc",
+				ContainerNameOrID: "jadda-jadda-infra",
+				RestartPolicy:     "always",
+				PIDFile:           "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
+				StopTimeout:       10,
+				PodmanVersion:     "CI",
+				RequiredServices:  []string{"container-1", "container-2"},
 			},
 			podGoodName,
 			false,
 		},
 		{"bad restart policy",
-			ContainerInfo{
+			containerInfo{
 				Executable:    "/usr/bin/podman",
 				ServiceName:   "639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
 				RestartPolicy: "never",
@@ -267,61 +269,61 @@ WantedBy=multi-user.target default.target`
 			true,
 		},
 		{"good with name and generic",
-			ContainerInfo{
-				Executable:    "/usr/bin/podman",
-				ServiceName:   "jadda-jadda",
-				ContainerName: "jadda-jadda",
-				RestartPolicy: "always",
-				PIDFile:       "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
-				StopTimeout:   42,
-				PodmanVersion: "CI",
-				New:           true,
-				CreateCommand: []string{"I'll get stripped", "container", "run", "--name", "jadda-jadda", "--hostname", "hello-world", "awesome-image:latest", "command", "arg1", "...", "argN"},
+			containerInfo{
+				Executable:        "/usr/bin/podman",
+				ServiceName:       "jadda-jadda",
+				ContainerNameOrID: "jadda-jadda",
+				RestartPolicy:     "always",
+				PIDFile:           "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
+				StopTimeout:       42,
+				PodmanVersion:     "CI",
+				New:               true,
+				CreateCommand:     []string{"I'll get stripped", "container", "run", "--name", "jadda-jadda", "--hostname", "hello-world", "awesome-image:latest", "command", "arg1", "...", "argN"},
 			},
 			goodNameNew,
 			false,
 		},
 		{"good with explicit short detach param",
-			ContainerInfo{
-				Executable:    "/usr/bin/podman",
-				ServiceName:   "jadda-jadda",
-				ContainerName: "jadda-jadda",
-				RestartPolicy: "always",
-				PIDFile:       "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
-				StopTimeout:   42,
-				PodmanVersion: "CI",
-				New:           true,
-				CreateCommand: []string{"I'll get stripped", "container", "run", "-d", "--name", "jadda-jadda", "--hostname", "hello-world", "awesome-image:latest", "command", "arg1", "...", "argN"},
+			containerInfo{
+				Executable:        "/usr/bin/podman",
+				ServiceName:       "jadda-jadda",
+				ContainerNameOrID: "jadda-jadda",
+				RestartPolicy:     "always",
+				PIDFile:           "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
+				StopTimeout:       42,
+				PodmanVersion:     "CI",
+				New:               true,
+				CreateCommand:     []string{"I'll get stripped", "container", "run", "-d", "--name", "jadda-jadda", "--hostname", "hello-world", "awesome-image:latest", "command", "arg1", "...", "argN"},
 			},
 			goodNameNew,
 			false,
 		},
 		{"good with explicit full detach param",
-			ContainerInfo{
-				Executable:    "/usr/bin/podman",
-				ServiceName:   "jadda-jadda",
-				ContainerName: "jadda-jadda",
-				RestartPolicy: "always",
-				PIDFile:       "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
-				StopTimeout:   42,
-				PodmanVersion: "CI",
-				New:           true,
-				CreateCommand: []string{"I'll get stripped", "container", "run", "--detach", "--name", "jadda-jadda", "--hostname", "hello-world", "awesome-image:latest", "command", "arg1", "...", "argN"},
+			containerInfo{
+				Executable:        "/usr/bin/podman",
+				ServiceName:       "jadda-jadda",
+				ContainerNameOrID: "jadda-jadda",
+				RestartPolicy:     "always",
+				PIDFile:           "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
+				StopTimeout:       42,
+				PodmanVersion:     "CI",
+				New:               true,
+				CreateCommand:     []string{"I'll get stripped", "container", "run", "--detach", "--name", "jadda-jadda", "--hostname", "hello-world", "awesome-image:latest", "command", "arg1", "...", "argN"},
 			},
 			goodNameNewDetach,
 			false,
 		},
 		{"good with id and no param",
-			ContainerInfo{
-				Executable:    "/usr/bin/podman",
-				ServiceName:   "container-639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
-				ContainerName: "639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
-				RestartPolicy: "always",
-				PIDFile:       "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
-				StopTimeout:   10,
-				PodmanVersion: "CI",
-				New:           true,
-				CreateCommand: []string{"I'll get stripped", "container", "run", "awesome-image:latest"},
+			containerInfo{
+				Executable:        "/usr/bin/podman",
+				ServiceName:       "container-639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
+				ContainerNameOrID: "639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401",
+				RestartPolicy:     "always",
+				PIDFile:           "/var/run/containers/storage/overlay-containers/639c53578af4d84b8800b4635fa4e680ee80fd67e0e6a2d4eea48d1e3230f401/userdata/conmon.pid",
+				StopTimeout:       10,
+				PodmanVersion:     "CI",
+				New:               true,
+				CreateCommand:     []string{"I'll get stripped", "container", "run", "awesome-image:latest"},
 			},
 			goodIDNew,
 			false,
@@ -330,11 +332,11 @@ WantedBy=multi-user.target default.target`
 	for _, tt := range tests {
 		test := tt
 		t.Run(tt.name, func(t *testing.T) {
-			opts := Options{
+			opts := entities.GenerateSystemdOptions{
 				Files: false,
 				New:   test.info.New,
 			}
-			got, err := CreateContainerSystemdUnit(&test.info, opts)
+			got, err := createContainerSystemdUnit(&test.info, opts)
 			if (err != nil) != test.wantErr {
 				t.Errorf("CreateContainerSystemdUnit() error = \n%v, wantErr \n%v", err, test.wantErr)
 				return
diff --git a/pkg/systemd/generate/pods.go b/pkg/systemd/generate/pods.go
new file mode 100644
index 000000000..16f324f78
--- /dev/null
+++ b/pkg/systemd/generate/pods.go
@@ -0,0 +1,130 @@
+package generate
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/containers/libpod/libpod"
+	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/pkg/errors"
+)
+
+// PodUnits generates systemd units for the specified pod and its containers.
+// 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) (string, error) {
+	if options.New {
+		return "", errors.New("--new 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() {
+		return "", fmt.Errorf("error generating systemd unit files: Pod %q has no infra container", pod.Name())
+	}
+
+	podInfo, err := generatePodInfo(pod, options)
+	if err != nil {
+		return "", err
+	}
+
+	infraID, err := pod.InfraContainerID()
+	if err != nil {
+		return "", err
+	}
+
+	// Compute the container-dependency graph for the Pod.
+	containers, err := pod.AllContainers()
+	if err != nil {
+		return "", err
+	}
+	if len(containers) == 0 {
+		return "", fmt.Errorf("error generating systemd unit files: Pod %q has no containers", pod.Name())
+	}
+	graph, err := libpod.BuildContainerGraph(containers)
+	if err != nil {
+		return "", err
+	}
+
+	// Traverse the dependency graph and create systemdgen.containerInfo's for
+	// each container.
+	containerInfos := []*containerInfo{podInfo}
+	for ctr, dependencies := range graph.DependencyMap() {
+		// Skip the infra container as we already generated it.
+		if ctr.ID() == infraID {
+			continue
+		}
+		ctrInfo, err := generateContainerInfo(ctr, options)
+		if err != nil {
+			return "", err
+		}
+		// Now add the container's dependencies and at the container as a
+		// required service of the infra container.
+		for _, dep := range dependencies {
+			if dep.ID() == infraID {
+				ctrInfo.BoundToServices = append(ctrInfo.BoundToServices, podInfo.ServiceName)
+			} else {
+				_, serviceName := containerServiceName(dep, options)
+				ctrInfo.BoundToServices = append(ctrInfo.BoundToServices, serviceName)
+			}
+		}
+		podInfo.RequiredServices = append(podInfo.RequiredServices, ctrInfo.ServiceName)
+		containerInfos = append(containerInfos, ctrInfo)
+	}
+
+	// Now generate the systemd service for all containers.
+	builder := strings.Builder{}
+	for i, info := range containerInfos {
+		if i > 0 {
+			builder.WriteByte('\n')
+		}
+		out, err := createContainerSystemdUnit(info, options)
+		if err != nil {
+			return "", err
+		}
+		builder.WriteString(out)
+	}
+
+	return builder.String(), nil
+}
+
+func generatePodInfo(pod *libpod.Pod, options entities.GenerateSystemdOptions) (*containerInfo, error) {
+	// Generate a systemdgen.containerInfo for the infra container. This
+	// containerInfo acts as the main service of the pod.
+	infraCtr, err := pod.InfraContainer()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not find infra container")
+	}
+
+	timeout := infraCtr.StopTimeout()
+	if options.StopTimeout != nil {
+		timeout = *options.StopTimeout
+	}
+
+	config := infraCtr.Config()
+	conmonPidFile := config.ConmonPidFile
+	if conmonPidFile == "" {
+		return nil, errors.Errorf("conmon PID file path is empty, try to recreate the container with --conmon-pidfile flag")
+	}
+
+	createCommand := []string{}
+
+	nameOrID := pod.ID()
+	ctrNameOrID := infraCtr.ID()
+	if options.Name {
+		nameOrID = pod.Name()
+		ctrNameOrID = infraCtr.Name()
+	}
+	serviceName := fmt.Sprintf("%s%s%s", options.PodPrefix, options.Separator, nameOrID)
+
+	info := containerInfo{
+		ServiceName:       serviceName,
+		ContainerNameOrID: ctrNameOrID,
+		RestartPolicy:     options.RestartPolicy,
+		PIDFile:           conmonPidFile,
+		StopTimeout:       timeout,
+		GenerateTimestamp: true,
+		CreateCommand:     createCommand,
+	}
+	return &info, nil
+}