fix(node): restore layer1 validator metrics overrides

[curryxbo]

Problem

PR #966 removed the standalone layer1 validator metrics CLI/environment overrides. Operators can configure metrics through Tendermint [instrumentation], but can no longer override the enable switch or listener port from deployment environment variables without editing config.toml.

Fix

Restore two overrides for layer1 verification mode only:

• --metrics-server-enable / MORPH_NODE_METRICS_SERVER_ENABLE overrides [instrumentation] prometheus for the standalone layer1 validator listener.
• --metrics-port / MORPH_NODE_METRICS_PORT replaces only that listener port while preserving the hostname from prometheus_listen_addr.

When neither option is set, behavior comes entirely from config.toml. Other modes continue using Tendermint metrics and are unaffected by these compatibility flags.

Validation

• go test ./derivation ./cmd/node ./flags
• make -C node lint

[coderabbitai]

📝 Walkthrough

Walkthrough

Layer1 verify mode resolves the validator metrics address from optional CLI/environment overrides, with fallback to Tendermint configuration and a default port when only a hostname is provided.

Changes

Validator metrics overrides

Layer / File(s)	Summary
Metrics flag definitions and registration node/flags/flags.go	Adds metrics-hostname and metrics-port flags, derives their environment variables, and registers them in the node flag set.
Metrics address resolution and verification wiring node/cmd/node/main.go, node/cmd/node/main_test.go	Resolves metrics overrides for Layer1 verify mode, defaults the port when needed, preserves configured addresses when unset, and tests address formatting and zero-port handling.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: dylancai9

Sequence Diagram(s)

sequenceDiagram
  participant CLI as CLI or environment
  participant Resolver as resolveValidatorMetricsAddr
  participant VerifyMode as Layer1 verify mode
  participant MetricsServer as Validator metrics server
  CLI->>Resolver: Provide metrics hostname and port
  Resolver->>VerifyMode: Return override or fallback address
  VerifyMode->>MetricsServer: Start server on resolved address

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: restoring layer1 validator metrics overrides.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/validator-metrics-port-config

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@node/cmd/node/main.go`:
- Around line 419-434: Update resolveValidatorMetricsAddr to use ctx.IsSet for
metrics hostname and port, preserving the fallback only when neither option is
set and retaining an explicitly provided port value of zero. Apply
defaultMetricsPort only when the port is genuinely unset, then construct the
address with net.JoinHostPort so IPv6 hosts are bracketed correctly; convert the
port to the required string form using strconv.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: fa44c184-e866-45bc-9445-86ec7c0c4088

📥 Commits

Reviewing files that changed from the base of the PR and between 60a7515 and 7fce578.

📒 Files selected for processing (2)

• node/cmd/node/main.go
• node/flags/flags.go

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@node/cmd/node/main_test.go`:
- Around line 51-55: Update the subtests in the tests loop to clear inherited
MORPH_NODE_METRICS_HOSTNAME and MORPH_NODE_METRICS_PORT before applying each
case’s configured environment values, ensuring fallback, hostname-only, and
port-only scenarios run independently of ambient variables.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 5ce06bcf-bcd6-4478-a99b-bd31fb463cae

📥 Commits

Reviewing files that changed from the base of the PR and between 7fce578 and 94d181a.

📒 Files selected for processing (2)

• node/cmd/node/main.go
• node/cmd/node/main_test.go

🚧 Files skipped from review as they are similar to previous changes (1)

• node/cmd/node/main.go