Pin apt child process locale in UpdatesCollector

[LarsLaskowski]

📖 Description

UpdatesCollector.Collect (internal/collector/updates.go) shells out to apt list --upgradable and parses its output with an English-only regex. The child process environment was built by appending DEBIAN_FRONTEND=noninteractive to os.Environ(), so on any host running a non-English locale (e.g. de_DE.UTF-8), apt localises its output via gettext ([upgradable from: ...] becomes [aktualisierbar von: ...]), the parser regex never matches, and Updates.Count silently reports 0 forever — with no error, no log warning, and no visible symptom other than a dashboard that always looks fully up to date.

This is a fix, not a feature: it builds the child environment explicitly instead of inheriting the operator's, forcing LC_ALL=C, LANG=C, and LANGUAGE= so apt output is always in the English form the parser expects, while preserving PATH so the bare "apt" command still resolves via exec.LookPath.

🎫 Issues

Closes #100

👩‍💻 Reviewer Notes

The only functional change is the cmd.Env assignment in UpdatesCollector.Collect. parseAptListUpgradable and the strings.HasPrefix(line, "Listing...") skip are unchanged — they were already correct for LC_ALL=C output, they just never received it in a non-English environment.

📑 Test Plan

Added TestUpdatesCollector_Collect_PinsLocale to internal/collector/updates_test.go, following the existing writeFakeVcgencmd stub-binary pattern used elsewhere in this file (no real apt binary or real locale data involved, per docs/TESTS.md):

• Points aptPath at a small shell script that dumps its own environment (env > file) instead of a real apt binary.
• Asserts the captured child environment has LC_ALL=C, LANG=C, and an empty LANGUAGE.
• Asserts PATH is still present in the child environment — a regression guard, since building cmd.Env from scratch instead of appending to os.Environ() could otherwise silently drop PATH and break command resolution.

Ran locally:

• go build ./...
• go vet ./...
• go test ./... -race -cover — all packages pass, internal/collector at 90.8% coverage
• golangci-lint run — 0 issues

✅ Checklist

General

• I have added/updated tests for my changes (go test ./... -race -cover passes locally).
• go vet ./... and golangci-lint run are clean.
• I have tested my changes.
• I have read the CONTRIBUTING documentation and followed the project's code style guidelines.
• I have updated ARCHITECTURE.md if this changes a documented design decision. (N/A — internal parsing detail, no documented design decision changes.)

REST API / configuration / packaging

Not applicable — no REST API, configuration, or packaging changes.

⏭ Next Steps

None. As noted in the issue, a more robust long-term option (parsing apt-get --just-print upgrade or reading dpkg/apt state directly) is a larger change and intentionally out of scope here.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud