[CI:DOCS] rootless: Tell the user what was led to the error, not just what it is

[andrewshadura]

Users coming e.g. from Docker do not always read the manual and expect podman to not require sudo or uidmap, for them the default message is not very helpful:

Error: Cannot connect to the Podman socket, make sure there is a Podman REST API service running.:
cannot find newuidmap: exec: "newuidmap": executable file not found in $PATH

Adding a bit more context to this would help to nudge them into the right direction and tell them what to look for in the documentation:

cannot find newuidmap required for rootless mode (try running as root?): exec: "newuidmap": executable file not found in $PATH

Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk>

[mheon]

Running as root there doesn't seem like the right suggestion? If newuidmap is missing, it needs to be installed.

[andrewshadura]

Running as root there doesn't seem like the right suggestion? If newuidmap is missing, it needs to be installed.

Well, it is if they didn’t intend to run rootless.

[wladmis]

Running as root there doesn't seem like the right suggestion? If newuidmap is missing, it needs to be installed.

To be clarified running as root does not mean that there will be root inside of container. This can be helpful when userns is not used.

[mheon]

But very few people didn't mean to run rootless. Rootless is one of Podman's most-used features, and I'd say we have more rootless users than root users. This error message is nonsensical for them, the majority of our users.

[andrewshadura]

How about try running as root if you didn’t want rootless mode?

[andrewshadura]

Or do you have a different, better phrasing in mind? I think it’s important to point out both options exist.

[mheon]

@TomSweeneyRedHat @rhatdan You two might have opinions here?

[TomSweeneyRedHat]

Beyond @rhatdan's comment, I'd a couple small nits in the text. Otherwise, TYVM @andrewshadura for the PR!

[giuseppe]

newuidmap/newgidmap are required only for rootless mode with multiple IDs available.

It is still possible to use rootless but you are limited to just one user, together with ignore_chown_errors

[andrewshadura]

newuidmap/newgidmap are required only for rootless mode with multiple IDs available.

It is still possible to use rootless but you are limited to just one user, together with ignore_chown_errors

How? I don’t think that’s documented very well, or at all?

[giuseppe]

How? I don’t think that’s documented very well, or at all?

yes, unfortunately this part is not documented properly, but you can try adding: podman --storage-opt ignore_chown_errors ... when a single ID is available and all the files will be owned by just one user.

It is not done automatically (and I think it shouldn't) because potentially it can lead to security problems when the files ownership inside the container matters.

[rhatdan]

Right, we recommend this only for specific use cases like HPC environments.
Bottom line is you will only be able to run with a single UID within the container and that UID will be fully privileged to do read/write anything in the container. If this works for you then you can use it.

Also pushing these types of containers to container registries, might cause some issues.

[github-actions]

A friendly reminder that this PR had no activity for 30 days.

[rhatdan]

@andrewshadura Still working on this?

[rhatdan]

LGTM

[rhatdan]

/approve

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[TomSweeneyRedHat]

LGTM

[TomSweeneyRedHat]

/lgtm