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You are viewing documentation of TeamCity 7.x, which is not the most recently released version of TeamCity. Please refer to the listing to choose another version.

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A TeamCity Build Agent is a piece of software that actually executes a build process. It is installed and configured separately from the TeamCity server. An agent can be installed on the same computer as the server or on a different machine (the latter is a preferred setup for server performance reasons).

An Agent typically checks out the source code, downloads artifacts of other builds and runs the build process. Number of agents basically limits the number of parallel builds and environments in which your build processes are run.

TeamCity server monitors all the connected agents and assigns queued builds to the agents based on compatibility requirements.

If there are several idle agents that can run a build TeamCity tries to select the fastest one based on the builds history.

In TeamCity, a build agent can have following statuses:



Connected/ Disconnected

An agent is connected if it is registered on the TeamCity server and responds to server commands, otherwise it is disconnected. This status is determined automatically.

Authorized/ Unauthorized

Agents are manually authorized via the web UI on the Agents page. Only authorized build agents can run builds. The number of simultaneously authorized agents cannot exceed the number of agent licenses in your license pool. When an agent is unauthorized, a license is freed and a different build agent can be authorized. Purchase additional licenses to expand the number of agents that can concurrently run builds. When a new agent is registered on the server for the first time, it is unauthorized by default and requires manual authorization to run the builds.

(info) If a build agent is installed and running on the same computer as TeamCity build server, it is authorized automatically.

Enabled/ Disabled

Agents are manually enabled/disabled via the web UI. The TeamCity server only distributes builds to agents that are enabled.

(info) Agent disabling does not affect (stop) the build which is currently running on the agent.

Disabled agents can still run builds, when the build is assigned to a special agent (e.g. by Triggering a Custom Build).
This feature is generally used to temporarily remove agents from the build grid to investigate agent-specific issues.

All agents connected to the server must have unique agent name.

Only users with certain roles can manage agents. See role and permission for more information.

For a build agent configuration please refer to Build Agent Configuration section.

Agent Upgrade

TeamCity agent is upgraded automatically when necessary. The process involves downloading new agent files from the TeamCity server and restarting the agent on new files. In order to successfully accomplish this, the user under which agent runs should have enough permissions.

Typically, an agent upgrade happens on:

  • server upgrade
  • agent plugin added or updated on the server
  • new tool installed (e.g. handle.exe for Swabra or new version of NuGet)

See also: