VCS Checkout Mode

Automatically on server

This is the default setting. The TeamCity server will export the sources and pass them to an agent before each build. Since the sources are exported rather than checked out, no administrative data is stored in the file system and version control operations (like check-in, label or update) cannot be performed from the agent. TeamCity optimizes communications with the VCS servers by caching the sources and retrieving from the VCS server only the necessary changes (Clean Checkout on that). Unless Clean Checkout is performed, the server sends to the agent incremental patches to update only the files changed since the last build on the agent in the given checkout directory.

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• The server side checkout simplifies administration overhead. Using this checkout mode, you need to install VCS client software on the server only (applicable to Perforce, Mercurial, TFS, Clearcase, VSS). Network access to VCS repository can also be opened to the server only. Thus, if you want to control who has access to the source repositories, the server side checkout is usually more effective.

• In some cases this checkout mode can lower the load produced on VCS repositories, especially if clean checkout is performed often, due to the caching of clean patches by the server.

• Note that in the server checkout mode the administration directories (like .svn, CVS) are not created on the agent.

Automatically on agent

The build agent will check out the sources before the build. This checkout mode is supported only for CVS, Subversion, TFS, Mercurial, Perforce, ClearCase and Git. Agent-side checkout frees more server resources and provides the ability to access version control-specific directories (.svn, CVS, .git); that is, the build script can perform VCS operations (e.g. check-ins into the version control) — in this case ensure the build script uses credentials necessary for the check-in.

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• Agent checkout is usually more effective with regard to data transfers and VCS server communications. The agent side checkout creates necessary administration directories (like .svn, CVS), and thus allows you to communicate with the repository from the build: commit changes and so on.

• Machine-specific settings (like configuring SSL communications, etc.) have to be configured on each machine using agent-side checkout.

• "Exclude" VCS Checkout Rules in most cases cannot improve agent checkout performance because an agent checks out the entire top-level directory included into a build, then deletes the files that were excluded. Perforce and TFS are exceptions to the rule, because before performing checkout, specific client mapping(Perforce)/workspace(TFS) is created based on checkout rules. "Exclude" checkout rules are not supported for Git and Mercurial when using checkout on an agent due to these DVCS limitations.

• Integration with certain version controls can provide additional options when agent-side checkout is used. For example, Subversion.

Do not check out files automatically

TeamCity will not check out any sources. The build script has to contain the commands to check out the sources. Please note that TeamCity will accurately report changes only if the checkout is performed on the revision specified by the Predefined Build Parameters properties passed into the build.