By default, the {% data variables.product.prodname_codeql_workflow %} uses the `on.push` event to trigger a code scan on every push to the default branch of the repository and any protected branches. For {% data variables.product.prodname_code_scanning %} to be triggered on a specified branch, the workflow must exist in that branch. For more information, see "[Workflow syntax for {% data variables.product.prodname_actions %}](/actions/reference/workflow-syntax-for-github-actions#on)."

The default {% data variables.product.prodname_codeql_workflow %} uses the `pull_request` event to trigger a code scan on pull requests targeted against the default branch. {% if currentVersion ver_gt "enterprise-server@2.21" %}The `pull_request` event is not triggered if the pull request was opened from a private fork.{% else %}If a pull request is from a private fork, the `pull_request` event will only be triggered if you've selected the "Run workflows from fork pull requests" option in the repository settings. For more information, see "[Disabling or limiting {% data variables.product.prodname_actions %} for a repository](/github/administering-a-repository/disabling-or-limiting-github-actions-for-a-repository#enabling-workflows-for-private-repository-forks)."{% endif %}

For more information about the `pull_request` event, see "[Workflow syntax for {% data variables.product.prodname_actions %}](/actions/reference/workflow-syntax-for-github-actions#onpushpull_requestbranchestags)."

You might want to avoid a code scan being triggered on specific pull requests targeted against the default branch, irrespective of which files have been changed. You can configure this by specifying `on:pull_request:paths-ignore` or `on:pull_request:paths` in the {% data variables.product.prodname_code_scanning %} workflow. For example, if the only changes in a pull request are to files with the file extensions `.md` or `.txt` you can use the following `paths-ignore` array.