A2A Protocol
Expose docker-agent agents via Google’s Agent-to-Agent (A2A) protocol for interoperability with other agent frameworks.
Overview
The docker agent serve a2a command starts an A2A server that exposes your agents using the A2A protocol. This enables communication between Docker Agent and other agent frameworks that support A2A.
⚠️ Early support
A2A support is functional but still evolving. Tool calls, artifacts, and memory features have limited A2A integration. See limitations below.
Usage
# Start A2A server for an agent
$ docker agent serve a2a ./agent.yaml
# Specify a custom address
$ docker agent serve a2a ./agent.yaml --listen 127.0.0.1:9000
# Use an agent from the catalog
$ docker agent serve a2a agentcatalog/pirate
Flags
| Flag | Default | Description |
|---|---|---|
-l, --listen <addr> |
127.0.0.1:8082 |
Address to listen on. |
-a, --agent <name> |
root |
Name of the agent to expose when the config contains multiple agents. |
--working-dir <path> |
current dir | Working directory the agent runs in. |
--env-from-file <file> |
(none) | Load additional environment variables from a .env file (repeatable). |
--models-gateway <url> |
(none) | Route all provider traffic through a models gateway URL. |
--code-mode-tools |
false |
Expose tools as a single “code” toolset that accepts a JavaScript snippet to run. |
--hook-pre-tool-use <cmd> |
(none) | Add a pre-tool-use hook (repeatable). See Hooks. |
--hook-post-tool-use <cmd> |
(none) | Add a post-tool-use hook (repeatable). |
--hook-session-start <cmd> |
(none) | Add a session-start hook (repeatable). |
--hook-session-end <cmd> |
(none) | Add a session-end hook (repeatable). |
--hook-on-user-input <cmd> |
(none) | Add an on-user-input hook (repeatable). |
--hook-stop <cmd> |
(none) | Add a stop hook, fired when the model finishes responding (repeatable). |
Features
- Auto port selection — Picks an available port if not specified
- Agent card — Provides standard A2A agent metadata
- Full docker-agent features — Supports all tools, models, and gateway features
- Multiple sources — Load agents from files or the agent catalog
💡 See also
For exposing agents via MCP instead, see MCP Mode. For stdio-based integration, see ACP. For the HTTP API, see API Server.
Current Limitations
- Tool calls are handled internally, not exposed as separate A2A events
- A2A artifact support not yet integrated
- A2A memory features not yet integrated
- Multi-agent (sub-agent) scenarios need further work