feat(machine-a-tron): logfmt logs in kubernetes

[poroh]

Currently machine-a-tron write colored logs to console that is not observability stack frendly.

This PR adds possibity to write logs in logfmt format that is common for other NICo components.

Related issues

N/A

Type of Change

• Add - New feature or capability
• Change - Changes in existing functionality
• Fix - Bug fixes
• Remove - Removed features or deprecated functionality
• Internal - Internal changes (refactoring, tests, docs, etc.)

Breaking Changes

• This PR contains breaking changes

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed
• No testing required (docs, internal refactor, etc.)

Additional Notes

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Summary by CodeRabbit

• New Features

  • Added configurable logging formats, including compact and structured logfmt output.
  • Added support for directing logs to standard output or files.
  • Added configuration options for local environments and Kubernetes deployments.
  • Helm deployments now support selecting the log format and include updated defaults and examples.

• Documentation

  • Added logging configuration guidance, including format selection and file redirection.

• Tests

  • Added coverage for logging configuration, structured output, and Helm-rendered settings.

Walkthrough

Machine-a-Tron now supports compact and logfmt logging. The selected format is configurable, validated, passed to runtime logging initialization, and exposed through local and Helm deployment configuration.

Changes

Machine-a-Tron logging configuration

Layer / File(s)	Summary
Logging format configuration contract crates/machine-a-tron/src/config.rs, crates/machine-a-tron/src/lib.rs	Adds the public LogFormat enum and the defaulted MachineATronConfig::log_format field. Deserialization tests cover supported and unsupported values.
Logging output implementation crates/machine-a-tron/Cargo.toml, crates/machine-a-tron/src/logging.rs	Adds stdout and file output handling for compact and logfmt tracing layers. The logfmt output includes a default component field and configurable filters.
Binary and integration-test wiring crates/machine-a-tron/src/main.rs, crates/api-integration-tests/tests/lib.rs, crates/api-integration-tests/tests/rack.rs	Routes configured logging through init_logging. Integration tests explicitly select compact output.
Deployment configuration and documentation crates/machine-a-tron/config/*, dev/docker-env/mat.toml, helm/charts/nico-machine-a-tron/*	Adds log_format settings to local and Helm configuration. The Helm template renders the setting and tests verify compact output. Documentation describes format and file options.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Merge Risk: 🟡 Moderate · up to 8f1aa

Default deployments can continue emitting non-logfmt logs, which may prevent the observability stack from parsing machine-a-tron output reliably. Merge should wait until the default behavior and documented logging policy are aligned.

Sequence Diagram(s)

sequenceDiagram
  participant MachineATron
  participant init_logging
  participant TracingSubscriber
  participant LogWriter
  participant TuiHostLogs
  MachineATron->>init_logging: pass configured LogFormat and log file
  init_logging->>TracingSubscriber: create compact or logfmt layer
  init_logging->>LogWriter: select stdout or file output
  init_logging->>TuiHostLogs: attach TUI logging when configured

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 42.86% 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
Title check	✅ Passed	The title clearly identifies the main change: adding logfmt logging for machine-a-tron in Kubernetes.
Description check	✅ Passed	The description explains the logfmt logging feature, its observability purpose, and its non-breaking scope.
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.

✨ Finishing Touches

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• Create PR with unit tests

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Actionable comments posted: 1

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Inline comments:
In `@crates/machine-a-tron/src/logging.rs`:
- Around line 75-90: Ensure the default service logging path emits logfmt by
updating the LogFormat::Compact handling in the logging initialization to use
the approved logfmt formatter, then align the omitted log_format default and
deployment documentation with this policy. Preserve the existing filtering, TUI
layer, writer configuration, and LogFormat::Logfmt behavior.

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📥 Commits

Reviewing files that changed from the base of the PR and between 641f0d4 and 8f1aada.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (14)

• crates/api-integration-tests/tests/lib.rs
• crates/api-integration-tests/tests/rack.rs
• crates/machine-a-tron/Cargo.toml
• crates/machine-a-tron/config/mac.toml
• crates/machine-a-tron/config/mat.toml
• crates/machine-a-tron/src/config.rs
• crates/machine-a-tron/src/lib.rs
• crates/machine-a-tron/src/logging.rs
• crates/machine-a-tron/src/main.rs
• dev/docker-env/mat.toml
• helm/charts/nico-machine-a-tron/README.md
• helm/charts/nico-machine-a-tron/templates/configmap.yaml
• helm/charts/nico-machine-a-tron/tests/configmap_test.yaml
• helm/charts/nico-machine-a-tron/values.yaml

[mnoori-afk]

Over all looks good to me.
Just for clarification the old compact way of logging never emittedspan-closed events and now we do. Does that mean we will be logging ~1500 log lines a second when ingesting 1000 hosts?

[poroh]

Over all looks good to me. Just for clarification the old compact way of logging never emittedspan-closed events and now we do. Does that mean we will be logging ~1500 log lines a second when ingesting 1000 hosts?

I don't know amount of log that will be ingested into observability stack during scaling tests but I think that this is different issue to solve if it has significant impact on performance (maybe we need somehow reduce logs for this specific case).