Application instrumentation

Brewlet does not auto-inject agents, detect language runtimes or reinterpret tracing configuration. Instrumentation follows ordinary application/runtime mechanisms under the same explicit descriptor and security contract.

Choose a delivery mechanism

Approach	Use when	Boundary
Application SDK/framework integration	The application already supports tracing/metrics.	Dependencies are application bytes and need their own updates.
Agent packaged under /app	An explicit agent is application-specific.	Producer authors paths and invocation; packaged bytes remain read-only.
Agent in an approved runtime	The platform deliberately standardizes an agent for that ID.	Runtime compatibility and source rotation govern the shared bytes.
Reviewed volume	Environment-specific agent/trust material is required.	Explicit mount and runtime-compatible configuration; no hidden discovery.

Use standard environment such as OTEL_SERVICE_NAME, OTEL_EXPORTER_OTLP_ENDPOINT and OTEL_RESOURCE_ATTRIBUTES only where the selected SDK/agent actually consumes them. These variables alone do not instrument an otherwise uninstrumented process.

Java example

Add the agent to the launch descriptor yourself. For example, a hand-written launch.json can set process.entrypoint to ["/usr/bin/java", "-javaagent:/app/agents/otel.jar", "-jar"] and process.args to ["/app/app.jar"]. Package a reviewed agent separately under /app (for example as its own --layer app=./agents:/app/agents), or deliberately use a compatible platform runtime with its own documented agent path. Verify compatibility and overhead.

With the Maven plugin, put -javaagent:/app/agents/otel.jar in the javaArgs configuration list; the generated argv places javaArgs before the class path and main class. Brewlet itself never adds -javaagent. A Pod args override replaces the descriptor's arguments and must preserve the complete intended invocation.

Python, Node and .NET

Use application SDKs or each ecosystem's documented explicit launcher/environment/profiler mechanisms. Package dependencies or select a runtime that provides them; Brewlet does not install packages at startup. Prefer recipes that work non-root and without a shell.

Verify before rollout

Confirm a real exported trace/metric reaches the intended collector, service identity is correct, secrets are scoped and resource limits leave agent headroom. An environment variable or an available collector is not export proof. Choose agent/SDK versions through the application's own governance process.

See resource behavior, certificate trust and node/control-plane metrics.