Fix handler and systemd activation errors

On panic from handler: log warning and stack trace, report
InternalServerError to client

When using `podman system service` make determining the listening endpoint deterministic.

  // When determining _*THE*_ listening endpoint --
  // 1) User input wins always
  // 2) systemd socket activation
  // 3) rootless honors XDG_RUNTIME_DIR
  // 4) if varlink -- adapter.DefaultVarlinkAddress
  // 5) lastly adapter.DefaultAPIAddress

Fixes #5150
Fixes #5151

Signed-off-by: Jhon Honce <jhonce@redhat.com>

1 files changed, 206 insertions, 0 deletions

diff --git a/pkg/systemd/generate/systemdgen.go b/pkg/systemd/generate/systemdgen.go
new file mode 100644
index 000000000..404347828
--- /dev/null
+++ b/pkg/systemd/generate/systemdgen.go
@@ -0,0 +1,206 @@
+package generate
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"text/template"
+	"time"
+
+	"github.com/containers/libpod/version"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// 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
+	// New controls if a new container is created or if an existing one is started.
+	New bool
+	// CreateCommand is the full command plus arguments of the process the
+	// container has been created with.
+	CreateCommand []string
+	// RunCommand is a post-processed variant of CreateCommand and used for
+	// the ExecStart field in generic unit files.
+	RunCommand 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)
+{{- 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}}
+{{- if .New}}
+ExecStartPre=/usr/bin/rm -f /%t/%n-pid /%t/%n-cid
+ExecStart={{.RunCommand}}
+ExecStop={{.Executable}} stop --ignore --cidfile /%t/%n-cid {{if (ge .StopTimeout 0)}}-t {{.StopTimeout}}{{end}}
+ExecStopPost={{.Executable}} rm --ignore -f --cidfile /%t/%n-cid
+PIDFile=/%t/%n-pid
+{{- else}}
+ExecStart={{.Executable}} start {{.ContainerName}}
+ExecStop={{.Executable}} stop {{if (ge .StopTimeout 0)}}-t {{.StopTimeout}}{{end}} {{.ContainerName}}
+PIDFile={{.PIDFile}}
+{{- end}}
+KillMode=none
+Type=forking
+
+[Install]
+WantedBy=multi-user.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
+}
+
+// CreateContainerSystemdUnit creates a systemd unit file for a container.
+func CreateContainerSystemdUnit(info *ContainerInfo, opts Options) (string, error) {
+	if err := validateRestartPolicy(info.RestartPolicy); err != nil {
+		return "", err
+	}
+
+	// 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
+	}
+
+	// Assemble the ExecStart command when creating a new container.
+	//
+	// Note that we cannot catch all corner cases here such that users
+	// *must* manually check the generated files.  A container might have
+	// 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 {
+		// The create command must at least have three arguments:
+		// 	/usr/bin/podman run $IMAGE
+		index := 2
+		if info.CreateCommand[1] == "container" {
+			index = 3
+		}
+		if len(info.CreateCommand) < index+1 {
+			return "", errors.Errorf("container's create command is too short or invalid: %v", info.CreateCommand)
+		}
+		// We're hard-coding the first five arguments and append the
+		// CreateCommand with a stripped command and subcomand.
+		command := []string{
+			info.Executable,
+			"run",
+			"--conmon-pidfile", "/%t/%n-pid",
+			"--cidfile", "/%t/%n-cid",
+			"--cgroups=no-conmon",
+		}
+		command = append(command, info.CreateCommand[index:]...)
+		info.RunCommand = strings.Join(command, " ")
+		info.New = true
+	}
+
+	if info.PodmanVersion == "" {
+		info.PodmanVersion = version.Version
+	}
+	if info.GenerateTimestamp {
+		info.TimeStamp = fmt.Sprintf("%v", time.Now().Format(time.UnixDate))
+	}
+
+	// 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 {
+		return "", errors.Wrap(err, "error parsing systemd service template")
+	}
+
+	var buf bytes.Buffer
+	if err := templ.Execute(&buf, info); err != nil {
+		return "", err
+	}
+
+	if !opts.Files {
+		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
+}