generate systemd

Implement `podman generate systemd` for Podman v2 and enable associated
tests.

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

1 files changed, 174 insertions, 0 deletions

diff --git a/pkg/domain/infra/abi/generate.go b/pkg/domain/infra/abi/generate.go
new file mode 100644
index 000000000..f69ba560e
--- /dev/null
+++ b/pkg/domain/infra/abi/generate.go
@@ -0,0 +1,174 @@
+package abi
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/containers/libpod/libpod"
+	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/containers/libpod/pkg/systemd/generate"
+	"github.com/pkg/errors"
+)
+
+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
+		}
+		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.
+	pod, err := ic.Libpod.LookupPod(nameOrID)
+	if err != nil {
+		return nil, err
+	}
+
+	// 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)
+	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 = "container"
+		name = ctr.ID()
+		if options.Name {
+			name = ctr.Name()
+		}
+		ctrName = name
+	} else {
+		kind = "pod"
+		name = pod.ID()
+		ctrName = ctr.ID()
+		if options.Name {
+			name = pod.Name()
+			ctrName = ctr.Name()
+		}
+	}
+	return ctrName, fmt.Sprintf("%s-%s", kind, name)
+}