Add useful diagnostics to the admin panel

[paulfitz]

Grist should be easier to install. Until it is, we can at least make it easier to find out what is going wrong. There's a page coming to help with that in https://github.com/gristlabs/grist-core/pull/850. So far it is pretty bare. This issue is to collect ideas for what to add to it. Here are some to start.

Edit: the page arrived, and a set of checks are now available in the admin panel. There are more than listed below. Continuing to add more here.

• [x] Is document sandboxing enabled and working?
• [ ] Is persistent volume writable? https://github.com/gristlabs/grist-core/pull/850#issuecomment-1948383961
• [ ] In multi-server setup, are workers reachable? https://github.com/gristlabs/grist-core/pull/850#issuecomment-1948383961
• [ ] Health of snapshot configuration - is it set up? are any life-cycle rules needed in place? https://github.com/gristlabs/grist-core/issues/857#issuecomment-1958870386

From https://community.getgrist.com/t/questions-about-self-hosted-grist-and-authentik-with-oidc/5250/2

• [ ] Show whether the anonymous playground is available, since many users might not expect that

[fflorent]

Here is a good way to check whether sandboxing exists or not: https://support.getgrist.com/self-managed/#how-do-i-sandbox-documents

Quoting:

To sanity-check that formulas are being evaluated within a sandbox, you can create a document and then check that this formula gives an empty result:

import glob
glob.glob('/etc/*')

[nbush]

A few notes on the current boot page copy in #850:

1. Is there a URL we could in add to the "Grist is reachable" part? Or do we not know that from here?
2. "Health" in second heading should be lowercase.
3. Also for the second heading: are there no docs describing what the health check actually checks?
4. "System user is sane": This should be more precise (and we should replace the term "sane" in this usage, at the very least). Is there a way to be more precise while retaining some charm (i.e. something better than just "System user is not root")?

[paulfitz]

Updated top level comment with another diagnostic from https://community.getgrist.com/t/questions-about-self-hosted-grist-and-authentik-with-oidc/5250/2