Amazon CodeCatalyst is no longer open to new customers. Existing customers can continue to use the service as normal. For more information, see [How to migrate from CodeCatalyst](migration.md).

# Connecting source repositories to workflows
<a name="workflows-sources"></a>

A *source*, also called an *input source*, is a source repository to which a [workflow action](workflows-actions.md) connects in order to obtain the files it needs to carry out its operations. For example, a workflow action might connect to a source repository to obtain application source files in order to build an application.

CodeCatalyst workflows support the following sources:
+ CodeCatalyst source repositories – For more information, see [Store and collaborate on code with source repositories in CodeCatalystStore and collaborate on code with source repositories](source.md).
+ GitHub repositories, Bitbucket repositories, and GitLab project repositories – For more information, see [Add functionality to projects with extensions in CodeCatalystAdd functionality to projects with extensions](extensions.md).

**Topics**
+ [Specifying a workflow file's source repository](workflows-sources-specify-workflow-def.md)
+ [Specifying a workflow action's source repository](workflows-sources-specify-action.md)
+ [Referencing source repository files](workflows-sources-reference-files.md)
+ ['BranchName' and 'CommitId' variables](workflows-sources-variables.md)