fix(orchestrator): use collision-free delimiters for harness config templating

[yusufozturk]

Summary

The harness rendered subject configs with Go's default text/template
delimiters ({{ }}). This collided with subject configs that carry their
own native templating using the conventional {{ }} / {{{ }}} braces
— e.g. vmetric smart-routing tokens like {{{_vmetric.table}}} and
file-target names like {{.Timestamp}}.

The result:

• The Go parser choked on {{{ (unexpected "{" in command).
• Subjects' own {{ }} tokens were mangled before they ever reached the subject.

This PR switches the harness to a distinct, collision-free delimiter pair
({{@ ... @}}) so that only harness-owned placeholders are rendered and
every native {{ }} / {{{ }}} token passes through verbatim.

Changes

• internal/orchestrator/docker.go

  • Introduce harnessTmplLeft ({{@) / harnessTmplRight (@}}) constants
    with a comment explaining the delimiter collision they avoid.
  • renderSubjectConfig now detects and parses templates using the harness
    delimiters via .Delims(...), instead of the default {{.
  • Updated the doc comment to clarify that configs using only their own
    native {{ }} tokens are passed through unchanged.

• cases/*/configs/axosyslog.conf (5 files)

  • Update the harness-owned {{.CPUs}} placeholder to the new
    {{@.CPUs@}} syntax:
    • otlp_grpc_to_otlp_grpc_correctness
    • otlp_grpc_to_otlp_grpc_performance
    • tcp_to_http_5min_performance
    • tcp_to_http_performance
    • tcp_to_http_persistent_correctness

Impact

• Non-templated subjects, directory-form configs (e.g. cribl-stream), and the
  existing missing-path tolerance are unaffected.
• Subjects that rely on native {{ }} / {{{ }}} templating now render
  correctly instead of failing or being corrupted.

Summary by CodeRabbit

• Bug Fixes
  • Improved template handling so configurations are rendered only when the new harness-style markers are present, reducing conflicts with existing config syntax.
  • Updated several performance and correctness test configurations to use the supported CPU placeholder format, helping tests run consistently across scenarios.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: a98d32b0-58ba-463b-b00b-d7bed611c701

📥 Commits

Reviewing files that changed from the base of the PR and between b586ab1 and 2533593.

📒 Files selected for processing (6)

• cases/otlp_grpc_to_otlp_grpc_correctness/configs/axosyslog.conf
• cases/otlp_grpc_to_otlp_grpc_performance/configs/axosyslog.conf
• cases/tcp_to_http_5min_performance/configs/axosyslog.conf
• cases/tcp_to_http_performance/configs/axosyslog.conf
• cases/tcp_to_http_persistent_correctness/configs/axosyslog.conf
• internal/orchestrator/docker.go

---

Walkthrough

The orchestrator now renders subject configs only when harness delimiters are present, using explicit delimiter parsing. The OTLP gRPC and TCP-to-HTTP case configs update workers(...) placeholders to the same harness syntax.

Changes

Harness templating update

Layer / File(s)	Summary
Rendering delimiters internal/orchestrator/docker.go	renderSubjectConfig now checks for harness-delimited template markers and parses with explicit custom delimiters.
Case config placeholders cases/otlp_grpc_to_otlp_grpc_*/configs/axosyslog.conf, cases/tcp_to_http_*/configs/axosyslog.conf	Five axosyslog.conf cases switch workers(...) from {{.CPUs}} to the harness-delimited CPU placeholder syntax.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• VirtualMetric/PipeBench#3: Introduces the templating path this PR refines by switching the renderer to harness delimiters and updating the matching case placeholders.

Poem

A bunny hopped by the config gate,
With curly braces now in a safer state.
{{@ and @}} dance neat and clear,
CPUs count fluff with less to fear.
🐇🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: switching harness templating to collision-free delimiters in the orchestrator.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch dev-temp-fix

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