feat(worker): add optional metrics_headers param to AgentexWorker and get_temporal_client

[alvinkam2001]

Problem

Temporal SDK internal metrics (workflow task latency, activity schedule-to-start latency, worker slot availability, sticky cache hit/miss rate, etc.) are emitted by the Temporal Rust bridge via OTLP. AgentexWorker already exposed a metrics_url parameter to configure the export endpoint, but had no way to pass authentication headers — making it impossible to export to backends that require them.

Rocket context

Rocket's SGP deployment uses Dynatrace (not the standard LGTM stack) for metrics and performance monitoring. Dynatrace OneAgent is injected into every pod via CSI driver and automatically provides two env vars:

• OTEL_EXPORTER_OTLP_ENDPOINT — the DT SaaS OTLP endpoint (https://<env>.live.dynatrace.com/api/v2/otlp)
• DT_API_TOKEN — an API token scoped for OTLP ingest

Application-level OTel (traces + custom metrics) already flows to Dynatrace via init_opentelemetry() which reads these env vars. Temporal SDK internal metrics were the only signal not reaching Dynatrace — specifically because the Rust bridge's OpenTelemetryConfig requires auth headers to be passed explicitly and there was no way to thread them through AgentexWorker.

Change

Adds an optional metrics_headers parameter to both AgentexWorker and get_temporal_client, passed through to OpenTelemetryConfig.headers in the Temporal runtime.

Behavior

• metrics_headers=None (default): identical to current behavior, no impact on existing deployments
• metrics_headers={...}: headers are forwarded to the Rust bridge's OTel exporter alongside metrics_url

Usage

worker = AgentexWorker(
    task_queue=task_queue_name,
    metrics_url=f"{os.environ['OTEL_EXPORTER_OTLP_ENDPOINT']}/v1/metrics",
    metrics_headers={"Authorization": f"Api-Token {os.environ['DT_API_TOKEN']}"},
)

Once wired up on the caller side, metrics like temporal_workflow_task_execution_latency, temporal_activity_schedule_to_start_latency, and temporal_worker_task_slots_available will appear in Dynatrace alongside the existing application traces.

Greptile Summary

The PR adds optional authentication headers for Temporal SDK OTLP metric exports while preserving existing positional API compatibility.

• Appends metrics_headers to both public call signatures.
• Forwards worker-supplied headers into OpenTelemetryConfig.
• Leaves existing behavior unchanged when no headers are supplied.

Confidence Score: 5/5

The PR appears safe to merge.

The previously reported positional compatibility issue is fixed by appending the new parameter after all existing parameters, and no blocking failure remains.

Important Files Changed

Filename	Overview
src/agentex/lib/core/temporal/workers/worker.py	Adds optional OTLP metrics headers at the end of both signatures and forwards them through the worker startup path without retaining the previously reported positional-binding break.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
    A[AgentexWorker metrics_headers] --> B[get_temporal_client]
    B --> C[OpenTelemetryConfig headers]
    C --> D[Temporal OTLP metrics exporter]

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_{Reviews (2): Last reviewed commit: "fix param ordering" | Re-trigger Greptile}