tracer-svc.md

tracer-svc overview

Architecture

The tracer-svc module is a proxy service, used to expose the REST API when the container-tracer runs in a Kubernetes context. It has the following main components:

• A REST API, that is used to interact with all tracer-node modules in the cluster. Look at REST API for a description of the API.
• An in-memory database with all tracer-node pods in the cluster.
• Logic for auto-discovery of tracer-node pods in the cluster. It runs periodically in the background, detects any changes and updates the database.
• A broadcast proxy logic, which is responsible for sending a received API request to all tracer-node pods, receiving and aggregating the responses and sending back the reply to the caller.

Parameters

On startup, tracer-svc checks for specific environment variables and accepts these input arguments:

• --address or TRACE_KUBE_API_ADDRESS: IP address and port in format IP:port, used to listen for incoming REST API requests. By default :8080 is used.
• --poll or TRACE_KUBE_DISCOVERY_POLL: Polling interval for tracer-node discovery, in seconds. By default, the discovery logic is triggered on every 10 seconds.
• --pods-selector or TRACE_KUBE_SELECTOR_PODS: Label selector for filtering tracer-node pods. By default app=container-tracer-backend is used. This label is used in the auto-discovery logic.
• --svc-selector or TRACE_KUBE_SELECTOR_SVCS: Field selector for filtering tracer-node service. By default metadata.name=container-tracer-node is used. This selector is used in the auto-discovery logic.
• --verbose or TRACE_KUBE_VERBOSE: Dump more detailed logs, disabled by default.

If both input argument and environment variable for a same setting exist, only the input argument is taken.