The Docker Swarm Collection Agent runs one OpenTelemetry Collector container on each node of a Docker Swarm, as a global Swarm service. It collects metrics and logs from each node and its containers, receives telemetry from your instrumented applications, and sends everything to SigNoz.
The Docker Swarm Collection Agent primarily performs the following:
- Collects host metrics such as CPU, memory, disk, and filesystem usage from each Swarm node.
- Collects resource usage metrics for each container from the Docker Engine of its node.
- Tails and parses the logs of the containers on each node and sends them to SigNoz.
- Acts as a gateway to send traces, metrics, and logs from your applications to SigNoz.
How it works
Agent (global service)
The agent reads each node through read-only mounts of the node's root filesystem and Docker's container log directory, and the node's Docker Engine API through the Docker socket. It runs as a global service, so Swarm runs one agent task on every node, including nodes that join later. Each task collects node-level and container-level data:
- Host metrics: CPU usage, memory consumption, disk I/O, filesystem usage, and load averages from the node. Network statistics describe the agent's own container, since the agent runs on its stack's network rather than the node's.
- Container metrics: CPU, memory, network, and block I/O usage of each container on the node, from the Docker Engine API. Metrics of Swarm tasks carry their stack, service, task, and node as
docker.stack.name,docker.service.name,docker.task.name, anddocker.node.id. - Container logs: Tailing and parsing the logs of the containers on the node. Each log record carries the
container.idresource attribute. - OTLP: Traces, metrics, and logs from instrumented applications, over OTLP/gRPC (4317) and OTLP/HTTP (4318), published on every node.
- Resource attributes:
host.nameon every signal, and on AWS, GCP, and Azure virtual machines the cloud provider, region, and instance.
Each task takes its node's hostname, so host.name names the Swarm node the data comes from.
