From: Lennart Poettering Date: Sat, 1 Nov 2025 21:21:32 +0000 (+0100) Subject: docs: add comment about requiring the mount hierarchy to be mounted MS_SHARED X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=32f4e30be58c2d5fabff32efbd4d266ae0d7503d;p=thirdparty%2Fsystemd.git docs: add comment about requiring the mount hierarchy to be mounted MS_SHARED This has been tripping up container manager people. let's document this explicitly. (Note that the container interface could really use some updates, i.e. it was written before a time where cgroup namespacing was a thing. But I am too lazy to fix that now, so let's just add this once facet.) --- diff --git a/docs/CONTAINER_INTERFACE.md b/docs/CONTAINER_INTERFACE.md index 77648395e96..3b33ce636ca 100644 --- a/docs/CONTAINER_INTERFACE.md +++ b/docs/CONTAINER_INTERFACE.md @@ -86,6 +86,12 @@ manager, please consider supporting the following interfaces. confuse systemd and the admin, but also prevent your implementation from being "stackable". +8. The mount hierarchy of the container should be mounted `MS_SHARED` before + invoking `systemd` as PID 1. Things will break at various places if this is + not done. Note that of course it's OK if the mounts are first marked + `MS_PRIVATE`/`MS_SLAVE` (to disconnect propagation at least partially) as + long as they are remounted `MS_SHARED` before `systemd` is invoked. + ## Environment Variables 1. To allow systemd (and other programs) to identify that it is executed within