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Update podman-generate-systemd man page
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Update links, content, and adding more examples to show how to run
the generated .service files as root and non-root. Fix for containers#5497

Signed-off-by: Sujil02 <[email protected]>
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sujil02 committed Apr 16, 2020
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2 changes: 1 addition & 1 deletion commands-demo.md
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| [podman-export(1)](https://podman.readthedocs.io/en/latest/markdown/podman-export.1.html) | Export container's filesystem contents as a tar archive |
| [podman-generate(1)](https://podman.readthedocs.io/en/latest/generate.html) | Generate structured output based on Podman containers and pods |
| [podman-generate-kube(1)](https://podman.readthedocs.io/en/latest/markdown/podman-generate-kube.1.html) | Generate Kubernetes YAML based on a pod or container |
| [podman-generate-systemd(1)](https://podman.readthedocs.io/en/latest/markdown/podman-generate-systemd.1.html) | Generate systemd unit file(s) for a container. Not supported for the remote client |
| [podman-generate-systemd(1)](https://podman.readthedocs.io/en/latest/markdown/podman-generate-systemd.1.html) | Generate systemd unit file(s) for a container or pod. Not supported for the remote client |
| [podman-history(1)](https://podman.readthedocs.io/en/latest/markdown/podman-history.1.html) | Shows the history of an image |
| [podman-image(1)](https://podman.readthedocs.io/en/latest/image.html) | Manage Images |
| [podman-image-exists(1)](https://podman.readthedocs.io/en/latest/markdown/podman-image-exists.1.html) | Check if an image exists in local storage |
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123 changes: 118 additions & 5 deletions docs/source/markdown/podman-generate-systemd.1.md
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% podman-generate-systemd(1)

## NAME
podman\-generate\-systemd - Generate systemd unit file(s) for a container. Not supported for the remote client
podman\-generate\-systemd - Generate systemd unit file(s) for a container or pod. Not supported for the remote client

## SYNOPSIS
**podman generate systemd** [*options*] *container|pod*
Expand All @@ -27,7 +27,9 @@ Use the name of the container for the start, stop, and description in the unit f
**--new**

Create a new container via podman-run instead of starting an existing one. This option relies on container configuration files, which may not map directly to podman CLI flags; please review the generated output carefully before placing in production.
Since we use systemd `Type=forking` service, using this option will force the container run with the detached param `-d`
Since we use systemd `Type=forking` service, using this option will force the container run with the detached param `-d`.

Note: Generating systemd unit files with `--new` flag is not yet supported for pods.

**--time**, **-t**=*value*

Expand All @@ -40,7 +42,10 @@ Set the systemd restart policy. The restart-policy must be one of: "no", "on-su

## Examples

Create and print a systemd unit file for a container running nginx with an *always* restart policy and 1-second timeout to stdout.
### Generate and print a systemd unit file for a container

Generate a systemd unit file for a container running nginx with an *always* restart policy and 1-second timeout to stdout.

```
$ podman create --name nginx nginx:latest
$ podman generate systemd --restart-policy=always -t 1 nginx
Expand All @@ -64,7 +69,42 @@ PIDFile=/run/user/1000/overlay-containers/de1e3223b1b888bc02d0962dd6cb5855eb0073
WantedBy=multi-user.target default.target
```

Create systemd unit files for a pod with two simple alpine containers. Note that these container services cannot be started or stopped individually via `systemctl`; they are managed by the pod service. You can still use `systemctl status` or journalctl to examine them.
### Generate systemd unit file for a container with `--new` flag

The `--new` flag generates systemd unit files that create and remove containers at service start and stop commands (see ExecStartPre and ExecStopPost service actions). Such unit files are not tied to a single machine and can easily be shared and used on other machines.

```
$ sudo podman generate systemd --new --files --name bb310a0780ae
# container-busy_moser.service
# autogenerated by Podman 1.8.3
# Fri Apr 3 09:40:47 EDT 2020
[Unit]
Description=Podman container-busy_moser.service
Documentation=man:podman-generate-systemd(1)
Wants=network.target
After=network-online.target
[Service]
Environment=PODMAN_SYSTEMD_UNIT=%n
Restart=on-failure
ExecStartPre=/usr/bin/rm -f %t/%n-pid %t/%n-cid
ExecStart=/usr/local/bin/podman run --conmon-pidfile %t/%n-pid --cidfile %t/%n-cid --cgroups=no-conmon -d -dit alpine
ExecStop=/usr/local/bin/podman stop --ignore --cidfile %t/%n-cid -t 10
ExecStopPost=/usr/local/bin/podman rm --ignore -f --cidfile %t/%n-cid
PIDFile=%t/%n-pid
KillMode=none
Type=forking
[Install]
WantedBy=multi-user.target default.target
```

### Generate systemd unit files for a pod with two simple alpine containers

Note `systemctl` should only be used on the pod unit and one should not start or stop containers individually via `systemctl`, as they are managed by the pod service along with the internal infra-container.

You can still use `systemctl status` or `journalctl` to examine container or pod unit files.
```
$ podman pod create --name systemd-pod
$ podman create --pod systemd-pod alpine top
Expand Down Expand Up @@ -96,9 +136,82 @@ PIDFile=/run/user/1000/overlay-containers/ccfd5c71a088768774ca7bd05888d55cc28769
WantedBy=multi-user.target default.target
```

### Installation of generated systemd unit files.

Podman-generated unit files include an `[Install]` section, which carries installation information for the unit. It is used by the enable and disable commands of systemctl(1) during installation.

Once you have generated the systemd unit file, you can copy the generated systemd file to ```/usr/lib/systemd/system``` for installing as a root user and to ```$HOME/.config/systemd/user ``` for installing it as a non-root user. Enable the copied unit file or files using `systemctl enable`.

Note: Coping unit files to ```/usr/lib/systemd/system``` and enabling it marks the unit file to be automatically started at boot. And smillarly, coping a unit file to ```$HOME/.config/systemd/user ``` and enabling it marks the unit file to be automatically started on user login.


```
# Generated systemd files.
$ podman pod create --name systemd-pod
$ podman create --pod systemd-pod alpine top
$ podman generate systemd --files --name systemd-pod
# Copy all the generated files.
$ sudo cp pod-systemd-pod.service container-great_payne.service /usr/lib/systemd/system
$ systemctl enable pod-systemd-po.service
Created symlink /etc/systemd/system/multi-user.target.wants/pod-systemd-po.service → /usr/lib/systemd/system/pod-systemd-po.service.
Created symlink /etc/systemd/system/default.target.wants/pod-systemd-po.service → /usr/lib/systemd/system/pod-systemd-po.service.
$ systemctl is-enabled pod-systemd-po.service
enabled
```
To run the user services placed in `$HOME/.config/systemd/user/` on first login of that user, enable the service with --user flag.

```
$ systemctl --user enable <.service>
```
The systemd user instance is killed after the last session for the user is closed. The systemd user instance can be kept running ever after the user logs out by enabling `lingering` using

```
$ loginctl enable-linger <username>
```
### Use `systemctl` to perform operations on generated installed unit files.

Create and enable systemd unit files for a pod using the above examples as reference and use `systemctl` to perform operations.

Since systemctl defaults to using the root user, all the changes using the systemctl can be seen by appending sudo to the podman cli commands. To perform `systemctl` actions as a non-root user use the `--user` flag when interacting with `systemctl`.

```
$ systemctl --user start pod-systemd-pod.service
$ podman pod ps
POD ID NAME STATUS CREATED # OF CONTAINERS INFRA ID
0815c7b8e7f5 systemd-pod Running 29 minutes ago 2 6c5d116f4bbe
$ sudo podman ps # 0 Number of pods on root.
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
$ systemctl stop pod-systemd-pod.service
$ podman pod ps
POD ID NAME STATUS CREATED # OF CONTAINERS INFRA ID
272d2813c798 systemd-pod Exited 29 minutes ago 2 6c5d116f4bbe
```

Create a simple alpine container and generate the systemd unit file with `--new` flag.
Enable the service and control operations using the systemctl commands.

Note: When starting the container using `systemctl start` rather than altering the already running container it spins up a "new" container with similar configuration.

```
# Enable the service.
$ sudo podman ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
bb310a0780ae docker.io/library/alpine:latest /bin/sh 2 minutes ago Created busy_moser
$ sudo systemctl start container-busy_moser.service
$ sudo podman ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
772df2f8cf3b docker.io/library/alpine:latest /bin/sh 1 second ago Up 1 second ago distracted_albattani
bb310a0780ae docker.io/library/alpine:latest /bin/sh 3 minutes ago Created busy_moser
```
## SEE ALSO
podman(1), podman-container(1), systemctl(1), systemd.unit(5), systemd.service(5)
[podman(1)](podman.1.md), [podman-container(1)](podman-container.1.md), systemctl(1), systemd.unit(5), systemd.service(5)

## HISTORY
April 2020, Updated details and added usecase to use generated .service files as root and non-root, by Sujil Shah (sushah at redhat dot com)

August 2019, Updated with pod support by Valentin Rothberg (rothberg at redhat dot com)

April 2019, Originally compiled by Brent Baude (bbaude at redhat dot com)
2 changes: 1 addition & 1 deletion docs/source/markdown/podman-generate.1.md
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| Command | Man Page | Description |
|---------|------------------------------------------------------------|-------------------------------------------------------------------------------------|
| kube | [podman-generate-kube(1)](podman-generate-kube.1.md) | Generate Kubernetes YAML based on a pod or container. |
| systemd | [podman-generate-systemd(1)](podman-generate-systemd.1.md) | Generate systemd unit file(s) for a container. Not supported for the remote client. |
| systemd | [podman-generate-systemd(1)](podman-generate-systemd.1.md) | Generate systemd unit file(s) for a container or pod. Not supported for the remote client. |


## SEE ALSO
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