feat: support per-runner-flavor SQS batch size and window in multi_runner_config

[Copilot]

Description

lambda_event_source_mapping_batch_size and lambda_event_source_mapping_maximum_batching_window_in_seconds are module-level variables applied identically to every runner flavor. Deployments with mixed load profiles (e.g. 1000-runner high-volume vs 10-runner low-volume) need per-flavor tuning to avoid unnecessary latency, wasted SSM throughput, and GitHub API rate limit pressure on low-volume flavors.

Adds both as optional(number, null) fields in multi_runner_config.runner_config, with coalesce() fallback to the existing module-level variables. Follows the established pattern used by scale_up_reserved_concurrent_executions.

Changes:

• modules/multi-runner/variables.tf — new optional fields in the runner_config object type + descriptions; restored iam_overrides fields accidentally dropped during merge
• modules/multi-runner/runners.tf — coalesce(per_flavor, module_level) for both parameters; restored iam_overrides wiring
• modules/multi-runner/README.md — regenerated with terraform-docs to reflect all changes; kept in sync with latest main

Usage:

multi_runner_config = {
  runner-large = {
    runner_config = {
      lambda_event_source_mapping_batch_size                         = 50   # override
      lambda_event_source_mapping_maximum_batching_window_in_seconds = 10   # override
      # ...
    }
  }
  runner-metal = {
    runner_config = {
      # no override — uses module-level defaults
      # ...
    }
  }
}

Fully backwards compatible. Existing configs require no changes.

Test Plan

• Verified with terraform fmt (clean)
• CodeQL security scan passed (no issues)
• Code review passed (no issues found)
• Confirmed iam_overrides is fully restored in runner_config object type, heredoc description, standalone variable, and runners.tf wiring
• Merged latest main and regenerated README; no remaining conflicts

Related Issues

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[wadherv]

@Brend-Smits can you please review this PR?

[Brend-Smits]

@copilot resolve the merge conflicts in this pull request

[Copilot]

Pull request overview

This PR adds per-runner-flavor overrides for SQS event source mapping tuning in the multi-runner module, allowing mixed runner fleets to use different Lambda batching behavior without changing global defaults.

Changes:

• Extends multi_runner_config.runner_config with per-flavor optional overrides for lambda_event_source_mapping_batch_size and lambda_event_source_mapping_maximum_batching_window_in_seconds.
• Updates the per-flavor module "runners" wiring to coalesce(per_flavor_override, module_level_default) for both settings.
• Regenerates/updates modules/multi-runner docs to reflect the new fields.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
modules/multi-runner/variables.tf	Adds optional per-flavor batch size/window fields to the runner_config object type and documents them in the multi_runner_config heredoc.
modules/multi-runner/runners.tf	Applies per-flavor overrides via coalesce() when passing event source mapping settings into the runners module.
modules/multi-runner/README.md	Updates the generated inputs documentation to include the new per-flavor configuration options.

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[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved the merge conflict in modules/multi-runner/README.md by merging origin/main and regenerating the terraform-docs section. Pushed in commit e530643.

[edersonbrilhante]

@Brend-Smits this PR is removing the iam_overrides added in the PR #4875

[Brend-Smits]

@Brend-Smits this PR is removing the iam_overrides added in the PR #4875

Good catch, thanks. Must have done something wrong when merging.

[Brend-Smits]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Merged origin/main into the branch and regenerated modules/multi-runner/README.md with terraform-docs. No conflicts remain.