Architecture
Overview
Section titled “Overview”dc-agent is a fleet-deployment system built on plain Jetty + servlets + Gson — no Spring, no DI framework. A lightweight HTTP agent runs on every managed host. The dc-operator — a multi-host web console — pushes work to those agents and supervises the services they run.
Internally the dependency graph is a star: every module depends only on dc-agent-core.
A task is a zipped service-definition directory (containing dc-docker.yml for the docker
flow). The agent materializes it into a daemontools service. docker/push applies it;
docker/check is a dry-run/diff.
The token channels
Section titled “The token channels”Each managed host is reached over separately-tokened channels:
- Task channel — a token sent as the
api-keyheader, used fordocker/pushanddocker/check(and the other task endpoints). - Control-plane channel — a token sent as
Bearer, used for/control-plane/api/*(service list/start/stop via daemontools), gated byCONTROL_PLANE_ENABLED. - App-status channel — a
Bearertoken (APP_STATUS_TOKEN), used for the always-on/app-statusendpoint that reports the instance’s version and health. Inoperator-config.yamlthis is the per-hostappStatusToken.
Modules
Section titled “Modules”dc-agent-app — the agent
Section titled “dc-agent-app — the agent”The HTTP agent that runs on each host (main class com.payneteasy.dcagent.DcAgentApplication).
Exposes the task/deploy, docker, app-status, and control-plane endpoints
on a raw Jetty server under context /dc-agent, port 8051.
dc-agent-core — shared library
Section titled “dc-agent-core — shared library”Config models, the job/task pipeline, the docker service engine (PushDockerAction), the
control-plane client, and crypto/zip/yaml utilities. Every other module depends on it.
dc-agent-operator (dc-operator) — web console
Section titled “dc-agent-operator (dc-operator) — web console”Multi-host React console driven from a git-backed config repo. Context /dc-operator, port
8052. See dc-operator.
Cross-cutting notes
Section titled “Cross-cutting notes”- Config is via startup parameters bound to environment variables (see Installation).
- HTTP layers differ: the agent runs a raw Jetty server; the operator runs on an internal mini-framework.
- Ports / contexts: agent
/dc-agenton8051; operator/dc-operatoron8052. - Serialization/crypto: Gson for JSON; YAML via a snakeyaml bridge; Handlebars for docker templating; docker artifact signatures are PGP.