systemd

var ContainerSocketTemplate = template.Must(template.New("unit.socket").Parse(`
[Unit]
Description=Container socket {{.Id}}

[Socket]
{{range .PortPairs}}ListenStream={{.External}}
{{end}}

[Install]
WantedBy=container-sockets.target
`))

var ContainerUnitTemplate = template.Must(template.New("unit.service").Parse(`
{{define "COMMON_UNIT"}}
[Unit]
Description=Container {{.Id}}
{{end}}

{{define "COMMON_SERVICE"}}
[Service]
Type=simple
TimeoutStartSec=5m
{{ if .Slice }}Slice={{.Slice}}{{ end }}
{{ if .EnvironmentPath }}EnvironmentFile={{.EnvironmentPath}}{{ end }}
{{end}}

{{define "COMMON_CONTAINER"}}
[Install]
WantedBy=container.target

# Container information
X-ContainerId={{.Id}}
X-ContainerImage={{.Image}}
X-ContainerUserId={{.User}}
X-ContainerRequestId={{.ReqId}}
X-ContainerType={{ if .Isolate }}isolated{{ else }}simple{{ end }}
{{range .PortPairs}}X-PortMapping={{.Internal}}:{{.External}}
{{end}}
{{end}}

{{/* A unit that lets docker own the container processes and only integrates via API */}}
{{define "SIMPLE"}}
{{template "COMMON_UNIT" .}}
{{template "COMMON_SERVICE" .}}
# Create data container
ExecStartPre=/bin/sh -c '/usr/bin/docker inspect --format="Reusing {{"{{.Id}}"}}" "{{.Id}}-data" || \
             exec docker run --name "{{.Id}}-data" {{.VolumeSpec}} --entrypoint /bin/true "{{.Image}}"'
ExecStartPre=-/usr/bin/docker rm "{{.Id}}"
{{ if .Isolate }}# Initialize user and volumes
ExecStartPre={{.ExecutablePath}} init --pre "{{.Id}}" "{{.Image}}"{{ end }}
ExecStart=/usr/bin/docker run --rm --name "{{.Id}}" \
          --volumes-from "{{.Id}}-data" \
          {{ if and .EnvironmentPath .DockerFeatures.EnvironmentFile }}--env-file "{{ .EnvironmentPath }}"{{ end }} \
          -a stdout -a stderr {{.PortSpec}} {{.RunSpec}} {{.BindMountSpec}} \
          {{ if .Isolate }} -v {{.RunDir}}:/.container.init:ro -u root {{end}} \
          "{{.Image}}" {{ if .Isolate }} /.container.init/container-init.sh {{ end }}
# Set links (requires container have a name)
ExecStartPost=-{{.ExecutablePath}} init --post "{{.Id}}" "{{.Image}}"
ExecReload=-/usr/bin/docker stop "{{.Id}}"
ExecReload=-/usr/bin/docker rm "{{.Id}}"
ExecStop=-/usr/bin/docker stop "{{.Id}}"
{{template "COMMON_CONTAINER" .}}
{{end}}

{{/* A unit that uses Docker with the 'foreground' flag to run an image under the current context */}}
{{define "FOREGROUND"}}
{{template "COMMON_UNIT" .}}
{{template "COMMON_SERVICE" .}}
# Create data container
ExecStartPre=/bin/sh -c '/usr/bin/docker inspect --format="Reusing {{"{{.Id}}"}}" "{{.Id}}-data" || \
             exec docker run --name "{{.Id}}-data" {{.VolumeSpec}} --entrypoint /bin/true "{{.Image}}"'
ExecStartPre=-/usr/bin/docker rm "{{.Id}}"
{{ if .Isolate }}# Initialize user and volumes
ExecStartPre={{.ExecutablePath}} init --pre "{{.Id}}" "{{.Image}}"{{ end }}
ExecStart=/usr/bin/docker run --rm --foreground \
          {{ if and .EnvironmentPath .DockerFeatures.EnvironmentFile }}--env-file "{{ .EnvironmentPath }}"{{ end }} \
          {{.PortSpec}} {{.RunSpec}} {{.BindMountSpec}} \
          --name "{{.Id}}" --volumes-from "{{.Id}}-data" \
          {{ if .Isolate }} -v {{.RunDir}}:/.container.init:ro -u root {{end}} \
          "{{.Image}}" {{ if .Isolate }} /.container.init/container-init.sh {{ end }}
# Set links (requires container have a name)
ExecStartPost=-{{.ExecutablePath}} init --post "{{.Id}}" "{{.Image}}"
{{template "COMMON_CONTAINER" .}}
{{end}}

{{/* A unit that exposes socket activation and process isolation */}}
{{define "SOCKETACTIVATED"}}
{{template "COMMON_UNIT" .}}
BindsTo={{.SocketUnitName}}

{{template "COMMON_SERVICE" .}}
ExecStartPre={{.ExecutablePath}} init --pre "{{.Id}}" "{{.Image}}"
ExecStart=/usr/bin/docker run \
            --name "{{.Id}}" \
            --volumes-from "{{.Id}}" \
            {{ if and .EnvironmentPath .DockerFeatures.EnvironmentFile }}--env-file "{{ .EnvironmentPath }}"{{ end }} \
            -a stdout -a stderr {{.RunSpec}} \
            --env LISTEN_FDS \
            -v {{.RunDir}}:/.container.init:ro \
            -v /usr/sbin/systemd-socket-proxyd:/usr/sbin/systemd-socket-proxyd:ro \
            -u root -f --rm \
            "{{.Image}}" /.container.init/container-init.sh
ExecStartPost=-{{.ExecutablePath}} init --post "{{.Id}}" "{{.Image}}"
{{template "COMMON_CONTAINER" .}}
X-SocketActivated={{.SocketActivationType}}
{{end}}

{{/* Run DEFAULT */}}
{{template "SIMPLE" .}}
`))

var SliceUnitTemplate = template.Must(template.New("unit.slice").Parse(`
[Unit]
Description=Container slice {{.Name}}

[Slice]
CPUAccounting=yes
MemoryAccounting=yes
MemoryLimit={{.MemoryLimit}}
{{ if .Parent }}Slice={{.Parent}}{{ end }}

[Install]
WantedBy=container.target container-active.target
`))

var TargetUnitTemplate = template.Must(template.New("unit.target").Parse(`
[Unit]
Description=Container target {{.Name}}

[Install]
WantedBy={{.WantedBy}}
`))