Merge pull request #10134 from rhatdan/conmon

[CI:DOCS] Add more documentation on conmon

docs/source/markdown/podman-container-cleanup.1.md

@@ -48,7 +48,7 @@ After cleanup, remove the image entirely.
 `podman container cleanup --latest`
 
 ## SEE ALSO
-podman(1), podman-container(1)
+**podman**(1), **podman-container**(1), **conmon**(8).
 
 ## HISTORY
 Jun 2018, Originally compiled by Dan Walsh <dwalsh@redhat.com>

docs/source/markdown/podman-create.1.md

@@ -1418,6 +1418,20 @@ $ podman start --attach ctr
 b
 ```
 
+## CONMON
+
+When Podman starts a container it actually executes the conmon program, which
+then executes the OCI Runtime.  Conmon is the container monitor.  It is a small
+program whose job is to watch the primary process of the container, and if the
+container dies, save the exit code.  It also holds open the tty of the
+container, so that it can be attached to later. This is what allows Podman to
+run in detached mode (backgrounded), so Podman can exit but conmon continues to
+run.  Each container has their own instance of conmon. Conmon waits for the
+container to exit, gathers and saves the exit code, and then launches a Podman
+process to complete the container cleanup, by shutting down the network and
+storage.   For more information on conmon, please reference the conmon(8) man
+page.
+
 ## FILES
 
 **/etc/subuid**
@@ -1427,7 +1441,7 @@ NOTE: Use the environment variable `TMPDIR` to change the temporary storage loca
 
 ## SEE ALSO
 **podman**(1), **podman-secret**(1), **podman-save**(1), **podman-ps**(1), **podman-attach**(1), **podman-pod-create**(1), **podman-port**(1), **podman-start*(1), **podman-kill**(1), **podman-stop**(1),
-**podman-generate-systemd**(1) **podman-rm**(1), **subgid**(5), **subuid**(5), **containers.conf**(5), **systemd.unit**(5), **setsebool**(8), **slirp4netns**(1), **fuse-overlayfs**(1), **proc**(5)**.
+**podman-generate-systemd**(1) **podman-rm**(1), **subgid**(5), **subuid**(5), **containers.conf**(5), **systemd.unit**(5), **setsebool**(8), **slirp4netns**(1), **fuse-overlayfs**(1), **proc**(5), **conmon**(8).
 
 ## HISTORY
 October 2017, converted from Docker documentation to Podman by Dan Walsh for Podman `<dwalsh@redhat.com>`

docs/source/markdown/podman-generate-systemd.1.md

@@ -233,7 +233,7 @@ CONTAINER ID  IMAGE                            COMMAND  CREATED        STATUS
 bb310a0780ae  docker.io/library/alpine:latest  /bin/sh  3 minutes ago  Created                      busy_moser
 ```
 ## SEE ALSO
-[podman(1)](podman.1.md), [podman-container(1)](podman-container.1.md), 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), **conmon**(8).
 
 ## 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)

docs/source/markdown/podman-run.1.md

@@ -1769,6 +1769,20 @@ $ podman run --env ENV*****=b alpine printenv ENV*****
 b
 ```
 
+## CONMON
+
+When Podman starts a container it actually executes the conmon program, which
+then executes the OCI Runtime.  Conmon is the container monitor.  It is a small
+program whose job is to watch the primary process of the container, and if the
+container dies, save the exit code.  It also holds open the tty of the
+container, so that it can be attached to later. This is what allows Podman to
+run in detached mode (backgrounded), so Podman can exit but conmon continues to
+run.  Each container has their own instance of conmon. Conmon waits for the
+container to exit, gathers and saves the exit code, and then launches a Podman
+process to complete the container cleanup, by shutting down the network and
+storage.   For more information on conmon, please reference the conmon(8) man
+page.
+
 ## FILES
 
 **/etc/subuid**
@@ -1779,7 +1793,7 @@ NOTE: Use the environment variable `TMPDIR` to change the temporary storage loca
 
 ## SEE ALSO
 **podman**(1), **podman-save**(1), **podman-ps**(1), **podman-attach**(1), **podman-pod-create**(1), **podman-port**(1), **podman-start**(1), **podman-kill**(1), **podman-stop**(1),
-**podman-generate-systemd**(1) **podman-rm**(1), **subgid**(5), **subuid**(5), **containers.conf**(5), **systemd.unit**(5), **setsebool**(8), **slirp4netns**(1), **fuse-overlayfs**(1), **proc**(5)**.
+**podman-generate-systemd**(1) **podman-rm**(1), **subgid**(5), **subuid**(5), **containers.conf**(5), **systemd.unit**(5), **setsebool**(8), **slirp4netns**(1), **fuse-overlayfs**(1), **proc**(5), **conmon**(8).
 
 ## HISTORY
 September 2018, updated by Kunal Kushwaha `<kushwaha_kunal_v7@lab.ntt.co.jp>`

docs/source/markdown/podman.1.md

@@ -343,7 +343,7 @@ The Network File System (NFS) and other distributed file systems (for example: L
 For more information, please refer to the [Podman Troubleshooting Page](https://github.com/containers/podman/blob/master/troubleshooting.md).
 
 ## SEE ALSO
-`containers-mounts.conf(5)`, `containers-registries.conf(5)`, `containers-storage.conf(5)`, `buildah(1)`, `containers.conf(5)`, `oci-hooks(5)`, `containers-policy.json(5)`, `crun(8)`, `runc(8)`, `subuid(5)`, `subgid(5)`, `slirp4netns(1)`
+**containers-mounts.conf**(5), **containers-registries.conf**(5), **containers-storage.conf**(5), **buildah**(1), **containers.conf**(5), **oci-hooks**(5), **containers-policy.json**(5), **crun**(8), **runc**(8), **subuid**(5), **subgid**(5), **slirp4netns**(1), **conmon**(8).
 
 ## HISTORY
 Dec 2016, Originally compiled by Dan Walsh <dwalsh@redhat.com>