Right now hooks that do mount magic do not work, because crun and podman will try to stat the source volume before even running hooks.
Refs:
Hopefully this will work in the future. For now below are the steps to test the hooks.
This is all being done inside the podman machine on a macbook.
$ podman machine init
$ podman machine start
$ podman machine ssh
Become root in the podman machine.
[core@localhost ~]$ sudo su -
Most of the podman machine is read-only, such is the nature of ostree. So the containers directory needs to be copied to a writable location and bind mounted back.
# mkdir -p /var/usr/share
# cp -rfvp /usr/share/containers /var/usr/share/
# mount -o bind /var/usr/share/containers /usr/share/containers
Directories for hooks and executables.
# mkdir -p /usr/share/containers/oci/hooks.d /usr/share/containers/oci/hooks.bin
Make podman hook.
cat <<EOF > /usr/share/containers/oci/hooks.d/testhook.json
{
"version": "1.0.0",
"hook": {
"path": "/usr/share/containers/oci/hooks.bin/oci-mount-fixer"
},
"when": {
"always": true
},
"stages": ["createRuntime","prestart"]
}
EOF
Make executable to be ran by hook.
echo '#!/bin/bash
echo running mount-fixer
echo $0 > /var/home/core/.oci-mount-fixer
echo $@ >> /var/home/core/.oci-mount-fixer
echo env_below >> /var/home/core/.oci-mount-fixer
env >> ~/.oci-mount-fixer
' > /usr/share/containers/oci/hooks.bin/oci-mount-fixer
Ensure executable has execute perms.
# chmod +x /usr/share/containers/oci/hooks.bin/oci-mount-fixer
Stop being root.
# exit
So this hook executable isn't going to work, this is just something I'm using to collect data in testing. The data will be in ~/.oci-mount-fixer. Before beginning, I made sure prior tests are cleaned with the file not there. The file existing is how I know the execuable ran without enabling debug output.
[core@localhost ~]$ ls -lah ~/.oci-mount-fixer
ls: cannot access '/var/home/core/.oci-mount-fixer': No such file or directory
I run podman with my custom hooks dir. At this point the hook is working. GREAT!
[core@localhost ~]$ podman run --rm alpine sh -c 'echo hello world'
Error: OCI runtime error: error executing hook `/var/home/core/.local/share/containers/oci/hooks.bin/oci-mount-fixer` (exit code: 1)
[core@localhost ~]$ ls -lah ~/.oci-mount-fixer
-rw-r--r--. 1 core core 80 Dec 18 16:58 /var/home/core/.oci-mount-fixer
Clean up and check if it runs when adding volumes? This does not work. Podman is stating before running hooks. Not sure this is right.
[core@localhost ~]$ rm -rf ~/.oci-mount-fixer
[core@localhost ~]$ ls -lah ~/.oci-mount-fixer
ls: cannot access '/var/home/core/.oci-mount-fixer': No such file or directory
[core@localhost ~]$ podman --hooks-dir ~/.local/share/containers/oci/hooks.d/ run -v /does/not/exist:/usr/src --rm alpine sh -c 'echo hello world'
Error: statfs /does/not/exist: no such file or directory
[core@localhost ~]$ ls -lah ~/.oci-mount-fixer
ls: cannot access '/var/home/core/.oci-mount-fixer': No such file or directory