[wak327]

Fixes #806

The daemon already has a --debug flag, but the snap gives users no way to turn it on. This PR adds two snap config options, following how the LXD snap does it:

• daemon.debug=true starts microcloudd with --debug.
• db.trace=true exports LIBDQLITE_TRACE=1 for the daemon, as requested in Allow enabling debug logging in MicroCloud #806 (comment).

Changes:

• snap/hooks/configure: snapd refuses snap set unless the snap has a configure hook. This hook validates that both keys are empty, true or false.
• snapcraft/commands/daemon.start: reads both keys with snapctl get when the daemon starts. The hook doesn't restart the daemon, so changes take effect after snap restart microcloud. The LXD snap behaves the same way.
• doc/how-to/snaps.md: adds an "Enable debug logging" section.

Usage:

sudo snap set microcloud daemon.debug=true
sudo snap restart microcloud

This affects MicroCloud's own logs, which go through the LXD logger. Microcluster's slog handler stays at its default level. Passing our level to it ties into the logger rework in #1084, so I left it out here.

Testing: I couldn't build the snap locally. I ran both scripts with stubbed snapctl and microcloudd binaries to check the arguments and environment for every combination of the two keys, and to check that the hook rejects values other than true and false.

Checklist

• I have read the contributing guidelines and attest that all commits in this PR are signed off, cryptographically signed, and follow this project's commit structure.
• I have checked and added or updated relevant documentation.

[wak327]

@roosterfish this adds snap set microcloud daemon.debug=true along the lines of your proposal in the issue. I couldn't build the snap locally, so I tested the hook and daemon.start with a stubbed snapctl. A quick check on an edge build would be welcome.

[Copilot]

🟢 Approval recommended

No unresolved blocking issues were identified.

No open issues 🎉

What changed in this PR

Adds snap configuration for daemon debug logging and dqlite tracing, with validation and documentation.

Changes:

• Adds daemon.debug and db.trace startup handling.
• Validates both options via the configure hook.
• Documents configuration usage.

File	Summary
snapcraft/​commands/​daemon.start	Applies debug and tracing settings at startup.
snap/​hooks/​configure	Validates snap configuration values.
doc/​how-to/​snaps.md	Documents the new snap options.

_{Review effort: Lite}

[roosterfish]

Thanks for this! To make it more accessible for users, please also add a note to the snapcraft.yaml, similar to how it's done in LXD ("Supported configuration options for the snap (snap set lxd [=...]):").

[wak327]

@roosterfish I addressed both points: the configure hook now rejects unsupported keys (402ec9f), and the snap description lists the supported options in the same style as LXD (1a10cbd). I also rebased onto main and folded the hook change into the commit that adds the hook. Could you take another look?

[Copilot]

🟡 Changes recommended

The configure hook does not correctly enumerate configured keys, so unsupported snap configuration keys are not rejected.

1 open issue

• Unsupported snap configuration keys bypass validation · New

_{Review effort: Lite}

[wak327]

@roosterfish I fixed how the configure hook reads the config: it now uses snapctl get "" "" to get the whole document, since a single empty key is rejected, and it fails if snapctl fails instead of skipping the check. I squashed the fix into the commit that adds the hook (d9a1855), so the PR is back to four commits. Could you take another look?

[wak327]

@roosterfish I simplified the configure hook as you suggested: it now just compares each set key against daemon.debug and db.trace, with a short awk script to list the keys. It's squashed into the hook commit (eff8732). Could you take another look?

[wak327]

@roosterfish the supported keys are now declared once in supported_keys and used for both checks, and the error only names the unsupported key. Squashed into the hook commit (f1016f0). Could you take another look?