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Where the Collector Runs
The river must flow somewhere. Close to the source, or gathered at the mouth. Each position serves a different purpose.
kubernetes concepts
Agent Modeper node / per pod
One collector per node (DaemonSet) or per pod (sidecar). Apps send to localhost. Lightweight processing.
Gateway Modecentralized
Centralized collector deployment. Multiple replicas behind a load balancer. Heavy processing that needs data from many services.
Your team needs lightweight batching close to each application. Which deployment mode?
Agent mode puts a collector right next to your apps. Batching, basic enrichment, and retry logic happen at the source — lightweight work that does not need a global view.
You need to sample traces that span 12 different services. Which deployment mode?
To sample a complete trace, you need to see all of its spans. An agent on a single node only sees local spans. A gateway sees spans from every service — it can make sampling decisions with the full picture.
the layered pattern
Agent mode handles the lightweight work close to the source. Gateway mode handles the heavy processing that requires seeing the whole picture.
In practice, agents forward to gateways. Each position in the flow serves its purpose.