[prometheus-node-exporter] Parameterise host root FS mount propagation

[weibeld]

Signed-off-by: Daniel Weibel [email protected]

What this PR does / why we need it:

The mounting of the node's root (/) file system was enabled by default in PR #80 and it was made optional in PR #757. However, in the state of PR #757, the mount propagation is still hardcoded to HostToContainer. However, this feature requires certain settings in the container runtime to work properly (see here). Without these settings, the container may fail to start up with an error of the following form:

Error: failed to start container "node-exporter": Error response from daemon: path / is mounted on / but it is not a shared or slave mount

This PR allows to freely define the mount propagation type in the values file:

hostRootFsMount:
  enabled: true
  mountPropagation: HostToContainer

In this way, it's possible to disable mount propagation when mounting the host root file system (by setting the field to None or omitting it), which allows to mount the host root file system on nodes that don't support mount propagation.

The default mount propagation value is set to HostToContainer to maintain backward compatibility with older versions of the chart.

Which issue this PR fixes

Various reports of the default mount propagation type causing the container to crash at startup can be found in #467.

Special notes for your reviewer:

Checklist

• DCO signed
• Chart Version bumped
• Title of the PR starts with chart name (e.g. [prometheus-couchdb-exporter])

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Any further update will cause the issue/pull request to no longer be considered stale. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Any further update will cause the issue/pull request to no longer be considered stale. Thank you for your contributions.