feat: support extra pipeline processors in events otel collector

[akila-i]

Purpose

The observability-events-otel-collector chart renders a hardcoded logs pipeline — configmap.yaml emits processors: [k8seventenrich, batch] as a literal, and the processors: block only ever defines those two. There is no way to insert a processor short of configOverride, which replaces the entire collector config and makes the operator own extensions, receiver storage, and pipelines by hand.

This blocks multi-cluster / multi-plane topologies, where several collectors fan into one backend and events need an origin attribute to stay distinguishable at query time.

configOverride does not actually solve it either. The distribution is a curated OCB build, so resource/... cannot be enabled by config at any level — the binary rejects it:

Error: 'processors' unknown type: "resource" for id: "resource/cluster_identity"
       (valid values: [k8seventenrich batch])

Resolves openchoreo/openchoreo#4402.

Approach

Adds a values-driven hook mirroring the existing exporters / pipelineExporters pair:

• builder-config.yaml — bundles the upstream resource and filter processors at v0.153.0, matching the existing pin.
• values.yaml — extraProcessors (definitions, keyed by processor ID) and pipelineProcessors (ordered chain). Defaults to [k8seventenrich, batch], so the rendered config is byte-identical to today's for anyone who does not opt in.
• configmap.yaml — renders an extraProcessors entry only when its key also appears in pipelineProcessors, exactly as exporters are gated on pipelineExporters. The pipeline line becomes processors: [{{ join ", " $pipelineProcessors }}].
• NOTES.txt — echoes the active chain post-install.
• README.md — a Customizing the pipeline section with worked examples for both processors.

Example:

collector:
  extraEnv:
    - { name: REGION, value: us-east-1 }
    - { name: PLANE_KIND, value: dataplane }
    - { name: PLANE_NAME, value: prod }

extraProcessors:
  resource/cluster_identity:
    attributes:
      - { key: cloud.region, value: "${env:REGION}", action: upsert }
      - { key: openchoreo.plane_kind, value: "${env:PLANE_KIND}", action: upsert }
      - { key: openchoreo.plane_name, value: "${env:PLANE_NAME}", action: upsert }

pipelineProcessors: [k8seventenrich, resource/cluster_identity, batch]

Env values need no new mechanism — collector.extraEnv already covers ${env:...}.

Render-time validation

Five fail guards, extending the existing pipelineExporters check. Three of them exist because the failure would otherwise be silent or badly diagnosed rather than to enforce style:

Guard	Why
Name is neither built-in nor in extraProcessors	Mirrors the existing pipelineExporters check
batch present but not last	Batching must happen after all other processing
extraProcessors key shadows k8seventenrich / batch	Built-in definitions are always rendered, so the key would appear twice. yaml.v3 sets uniqueKeys: true, making this a hard parse error surfacing only at pod start, behind a message that points nowhere near the cause
pipelineProcessors empty	The collector accepts processors: [] with exit 0 — enrichment and batching would be lost silently, with no error at any layer
Duplicate entries	Fails at runtime with references processor "batch" multiple times

The values are also normalised with | default dict / | default list before use. Helm's coalesce deletes keys whose user value is null, and sprig's hasKey/len/uniq error on an untyped nil — so extraProcessors: with a commented-out body (the most likely user typo) previously produced wrong type for value; expected map[string]interface {}; got interface {}. The same one-token fix is applied to the pre-existing hasKey .Values.exporters call, which had the identical latent bug.

Related Issues

• Resolves Support extra pipeline processors in events OTel collector module openchoreo#4402

Checklist

• Tests added or updated (unit, integration, etc.)
• Samples updated (if applicable)

Remarks

filter goes beyond the issue's stated scope. The issue asks only for resource. It is included because event volume is a real cost driver and nothing else bundled can express a drop rule.

This bumps VERSION to 0.2.0, so merging cuts a release (chart + image at 0.2.0, plus an observability-events-otel-collector-0.2.0 tag).

Summary by CodeRabbit

• New Features

  • Added configurable OpenTelemetry pipeline processors, including resource enrichment and event filtering.
  • Added support for defining extra processors and controlling their order in the logs pipeline.
  • Added environment-variable substitution for processor configuration.
  • Helm installation notes now display the effective pipeline configuration.

• Bug Fixes

  • Improved validation for exporter and processor configurations, including duplicates, unknown components, and invalid ordering.

• Documentation

  • Updated installation examples and guidance for chart version 0.2.0.
  • Added examples for resource attributes and filtering noisy events.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 9bde7ddd-51e0-4d1e-b082-2bd6d52dd0fb

📥 Commits

Reviewing files that changed from the base of the PR and between 91a7f4f and 2f23f79.

📒 Files selected for processing (3)

• observability-events-otel-collector/README.md
• observability-events-otel-collector/helm/templates/configmap.yaml
• observability-events-otel-collector/helm/values.yaml

📝 Walkthrough

Walkthrough

The collector module now supports resource and filter processors through Helm values. It validates and renders ordered pipeline processors, reports the effective pipeline, updates the package version to 0.2.0, and documents configuration examples.

Changes

OTel pipeline customization

Layer / File(s)	Summary
Processor components and values contract observability-events-otel-collector/VERSION, observability-events-otel-collector/builder-config.yaml, observability-events-otel-collector/helm/values.yaml, observability-events-otel-collector/README.md	The package version is 0.2.0. The collector includes resource and filter processors. Helm values define extra processors and an ordered pipeline processor list with batch last. Installation examples use chart version 0.2.0.
Helm pipeline validation and rendering observability-events-otel-collector/helm/templates/configmap.yaml, observability-events-otel-collector/helm/templates/NOTES.txt, observability-events-otel-collector/README.md	The chart validates processor and exporter settings, renders referenced extra processors, uses the configured pipeline, reports the effective pipeline, and documents resource and filter processor examples.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🟡 Moderate · up to 91a7f

The chart can currently render an unsupported processor that prevents the collector from starting, and it can accept a pipeline that omits required batching and silently changes processing behavior. These opt-in configuration paths should be corrected or explicitly accepted before merge.

Sequence Diagram(s)

sequenceDiagram
  participant HelmValues as Helm values
  participant ConfigMapTemplate as configmap.yaml
  participant OTelCollector as OpenTelemetry Collector
  HelmValues->>ConfigMapTemplate: Provide extraProcessors and pipelineProcessors
  ConfigMapTemplate->>ConfigMapTemplate: Validate processor references and ordering
  ConfigMapTemplate->>OTelCollector: Render processor definitions and logs pipeline

Loading

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the primary change and follows the required Conventional Commits format.
Description check	✅ Passed	The description includes all required sections and clearly explains the purpose, implementation, issue, checklist, and release context.
Linked Issues check	✅ Passed	The changes satisfy the linked issue [#4402] by adding configurable processors, validation, resource support, documentation, and environment-based values.
Out of Scope Changes check	✅ Passed	The changes remain within the extra-processor extensibility scope; filter support is a related processor use case and is explicitly documented.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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• Create PR with unit tests

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Actionable comments posted: 3

🤖 Prompt for all review comments with AI agents

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Inline comments:
In `@observability-events-otel-collector/helm/templates/configmap.yaml`:
- Around line 47-49: Update the structured pipeline validation around
pipelineProcessors so rendering fails when batch is absent or when batch is not
the final processor. Preserve the existing error behavior for an incorrectly
positioned batch and enforce the documented requirement that users explicitly
re-list batch.
- Around line 34-43: Update the processor validation around $pipelineProcessors
and $extraProcessors to parse every extra processor ID, reject empty or
malformed IDs, and allow only resource and filter processor types. Validate
pipeline references against these parsed, supported extra processors so IDs such
as transform/drop cannot pass merely because they exist in extraProcessors;
preserve the reserved built-in name check.

In `@observability-events-otel-collector/README.md`:
- Around line 250-257: Update the README pipeline example to include the
existing filter/warnings_only processor in pipelineProcessors, while preserving
its current extraProcessors definition and ordering the reference consistently
with the other processors.

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Fix all unresolved CodeRabbit comments on this PR:

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: b08a3ef1-4ec2-4941-b268-01ff58237b58

📥 Commits

Reviewing files that changed from the base of the PR and between ad903e1 and 91a7f4f.

📒 Files selected for processing (6)

• observability-events-otel-collector/README.md
• observability-events-otel-collector/VERSION
• observability-events-otel-collector/builder-config.yaml
• observability-events-otel-collector/helm/templates/NOTES.txt
• observability-events-otel-collector/helm/templates/configmap.yaml
• observability-events-otel-collector/helm/values.yaml

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