PMM-15295 Warn on Nomad without public address.

[JiriCtvrtka]

Ticket number: PMM-15295

Feature build: SUBMODULES-0

What

Emit a configuration warning when PMM_ENABLE_NOMAD is set but PMM_PUBLIC_ADDRESS is not, instead of silently skipping the Nomad server.

Why

Nomad needs both variables. With the flag alone, Settings.IsNomadEnabled() returns false and supervisord skips the nomad-server template — no error, no warning. The container is healthy and PMM works, so nothing indicates why nothing can be executed.

This cost real debugging time during SEP integration testing: SEP dispatches task execution through PMM's embedded Nomad, so the failure surfaces as "SEP cannot run anything", several layers away from one unset variable. The requirement is documented in documentation/docs/reference/nomad.md, but the runtime said nothing.

How

A post-loop cross-check in ParseEnvVars appending to the existing warns list — no new plumbing:

if envSettings.EnableNomad != nil && *envSettings.EnableNomad &&
    (envSettings.PMMPublicAddress == nil || *envSettings.PMMPublicAddress == "") {
    warns = append(warns, "PMM_ENABLE_NOMAD is set but PMM_PUBLIC_ADDRESS is not; Nomad will not start")
}

The warning reaches the operator through the same channel as every other environment-variable warning: pmm-managed-init/main.go logs it as Configuration warning: %s, and server.go via s.l.Warnln on UpdateSettingsFromEnv.

This is a diagnostic, not a new failure mode. Only warns is appended to; errs is untouched, so pmm-managed-init does not exit and PMM starts exactly as before.

Behaviour

Environment | Warning -- | -- PMM_ENABLE_NOMAD=1, no public address | yes PMM_ENABLE_NOMAD=1, PMM_PUBLIC_ADDRESS= (empty) | yes — IsNomadEnabled() also treats empty as disabled PMM_ENABLE_NOMAD=1 + public address | no PMM_ENABLE_NOMAD=0 | no Neither set | no Public address only | no PMM_ENABLE_NOMAD=maybe | no — the existing parse error already reports it

Testing

TestNomadWithoutPublicAddress in managed/utils/envvars/parser_test.go covers every row above. Statement and branch coverage of the new block is complete, and each sub-term of the predicate is exercised both true and false.

• go test ./managed/utils/envvars/... — pass
• bin/golangci-lint run managed/utils/envvars/... — 0 issues
• go build ./managed/..., go vet — clean

Out of scope

Changing the requirement itself — Nomad genuinely needs the public address.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 45.56%. Comparing base (31318c7) to head (1b8f7b4).
⚠️ Report is 158 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5849      +/-   ##
==========================================
+ Coverage   43.59%   45.56%   +1.97%     
==========================================
  Files         415      217     -198     
  Lines       43134    28116   -15018     
==========================================
- Hits        18804    12811    -5993     
+ Misses      22454    13920    -8534     
+ Partials     1876     1385     -491     

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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Run ID: 9b5bfc7d-204e-4c94-b261-eb3547addb5e

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Reviewing files that changed from the base of the PR and between 95c70a4 and 1b8f7b4.

📒 Files selected for processing (2)

• managed/utils/envvars/parser.go
• managed/utils/envvars/parser_test.go

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Walkthrough

ParseEnvVars now appends a warning when PMM_ENABLE_NOMAD is enabled and PMM_PUBLIC_ADDRESS is unset or empty. The warning states that Nomad will not start without a configured public address. TestNomadWithoutPublicAddress verifies warning presence and absence across seven environment-variable combinations. It also verifies that an invalid Nomad value returns one error and no warning.

Merge Risk: ⚪ Minimal · up to 1b8f7

This change warns operators when Nomad is enabled without the required public address, without altering service behavior or access controls. No actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: warning when Nomad is enabled without a public address.
Description check	✅ Passed	The description includes the required ticket number and feature build, explains what, why, and how, documents behavior and testing, and identifies out-of-scope work. The API documentation checkbox is …
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description includes the required ticket number and feature build, explains what, why, and how, documents behavior and testing, and identifies out-of-scope work. The API documentation checkbox is not required because this PR does not alter API endpoints.

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