--- type: tutorial --- # Triggering pipelines through the API > **Notes**: > > - [Introduced](https://about.gitlab.com/releases/2015/08/22/gitlab-7-14-released/) in GitLab 7.14. > - GitLab 8.12 has a completely redesigned job permissions system. Read all > about the [new model and its implications](../../user/project/new_ci_build_permissions_model.md#pipeline-triggers). Triggers can be used to force a pipeline rerun of a specific `ref` (branch or tag) with an API call. ## Authentication tokens The following methods of authentication are supported. ### Trigger token A unique trigger token can be obtained when [adding a new trigger](#adding-a-new-trigger). DANGER: **Danger:** Passing plain text tokens in public projects is a security issue. Potential attackers can impersonate the user that exposed their trigger token publicly in their `.gitlab-ci.yml` file. Use [variables](../variables/README.md#gitlab-cicd-environment-variables) to protect trigger tokens. ### CI job token You can use the `CI_JOB_TOKEN` [variable][predef] (used to authenticate with the [GitLab Container Registry][registry]) in the following cases. #### When used with multi-project pipelines > - Use of `CI_JOB_TOKEN` for multi-project pipelines was [introduced][ee-2017] in [GitLab Premium][ee] 9.3. > - Use of `CI_JOB_TOKEN` for multi-project pipelines was [made available](https://gitlab.com/gitlab-org/gitlab/issues/31573) in all tiers in GitLab 12.4. This way of triggering can only be used when invoked inside `.gitlab-ci.yml`, and it creates a dependent pipeline relation visible on the [pipeline graph](../multi_project_pipelines.md#overview). For example: ```yaml build_docs: stage: deploy script: - curl --request POST --form "token=$CI_JOB_TOKEN" --form ref=master https://gitlab.example.com/api/v4/projects/9/trigger/pipeline only: - tags ``` Pipelines triggered that way also expose a special variable: `CI_PIPELINE_SOURCE=pipeline`. Read more about the [pipelines trigger API][trigapi]. #### When a pipeline depends on the artifacts of another pipeline **(PREMIUM)** > The use of `CI_JOB_TOKEN` in the artifacts download API was [introduced][ee-2346] in [GitLab Premium][ee] 9.5. With the introduction of dependencies between different projects, one of them may need to access artifacts created by a previous one. This process must be granted for authorized accesses, and it can be done using the `CI_JOB_TOKEN` variable that identifies a specific job. For example: ```yaml build_submodule: image: debian stage: test script: - apt update && apt install -y unzip - curl --location --output artifacts.zip "https://gitlab.example.com/api/v4/projects/1/jobs/artifacts/master/download?job=test&job_token=$CI_JOB_TOKEN" - unzip artifacts.zip only: - tags ``` This allows you to use that for multi-project pipelines and download artifacts from any project to which you have access as this follows the same principles with the [permission model][permissions]. Read more about the [jobs API](../../api/jobs.md#download-the-artifacts-archive). ## Adding a new trigger You can add a new trigger by going to your project's **Settings ➔ CI/CD** under **Triggers**. The **Add trigger** button will create a new token which you can then use to trigger a rerun of this particular project's pipeline. Every new trigger you create, gets assigned a different token which you can then use inside your scripts or `.gitlab-ci.yml`. You also have a nice overview of the time the triggers were last used. ![Triggers page overview](img/triggers_page.png) ## Revoking a trigger You can revoke a trigger any time by going at your project's **Settings ➔ CI/CD** under **Triggers** and hitting the **Revoke** button. The action is irreversible. ## Triggering a pipeline > **Notes**: > > - Valid refs are only the branches and tags. If you pass a commit SHA as a ref, > it will not trigger a job. To trigger a job you need to send a `POST` request to GitLab's API endpoint: ```plaintext POST /projects/:id/trigger/pipeline ``` The required parameters are the [trigger's `token`](#authentication-tokens) and the Git `ref` on which the trigger will be performed. Valid refs are the branch and the tag. The `:id` of a project can be found by [querying the API](../../api/projects.md) or by visiting the **CI/CD** settings page which provides self-explanatory examples. When a rerun of a pipeline is triggered, the information is exposed in GitLab's UI under the **Jobs** page and the jobs are marked as triggered 'by API'. ![Marked rebuilds as on jobs page](img/builds_page.png) --- You can see which trigger caused the rebuild by visiting the single job page. A part of the trigger's token is exposed in the UI as you can see from the image below. ![Marked rebuilds as triggered on a single job page](img/trigger_single_build.png) --- By using cURL you can trigger a pipeline rerun with minimal effort, for example: ```shell curl --request POST \ --form token=TOKEN \ --form ref=master \ https://gitlab.example.com/api/v4/projects/9/trigger/pipeline ``` In this case, the project with ID `9` will get rebuilt on `master` branch. Alternatively, you can pass the `token` and `ref` arguments in the query string: ```shell curl --request POST \ "https://gitlab.example.com/api/v4/projects/9/trigger/pipeline?token=TOKEN&ref=master" ``` You can also benefit by using triggers in your `.gitlab-ci.yml`. Let's say that you have two projects, A and B, and you want to trigger a rebuild on the `master` branch of project B whenever a tag on project A is created. This is the job you need to add in project A's `.gitlab-ci.yml`: ```yaml build_docs: stage: deploy script: - "curl --request POST --form token=TOKEN --form ref=master https://gitlab.example.com/api/v4/projects/9/trigger/pipeline" only: - tags ``` This means that whenever a new tag is pushed on project A, the job will run and the `build_docs` job will be executed, triggering a rebuild of project B. The `stage: deploy` ensures that this job will run only after all jobs with `stage: test` complete successfully. ## Triggering a pipeline from a webhook > **Notes**: > > - Introduced in GitLab 8.14. > - `ref` should be passed as part of the URL in order to take precedence over > `ref` from the webhook body that designates the branch ref that fired the > trigger in the source repository. > - `ref` should be URL-encoded if it contains slashes. To trigger a job from a webhook of another project you need to add the following webhook URL for Push and Tag events (change the project ID, ref and token): ```plaintext https://gitlab.example.com/api/v4/projects/9/ref/master/trigger/pipeline?token=TOKEN ``` ## Making use of trigger variables You can pass any number of arbitrary variables in the trigger API call and they will be available in GitLab CI so that they can be used in your `.gitlab-ci.yml` file. The parameter is of the form: ```plaintext variables[key]=value ``` This information is also exposed in the UI. Please note that _values_ are only viewable by Owners and Maintainers. ![Job variables in UI](img/trigger_variables.png) Using trigger variables can be proven useful for a variety of reasons: - Identifiable jobs. Since the variable is exposed in the UI you can know why the rebuild was triggered if you pass a variable that explains the purpose. - Conditional job processing. You can have conditional jobs that run whenever a certain variable is present. Consider the following `.gitlab-ci.yml` where we set three [stages](../yaml/README.md#stages) and the `upload_package` job is run only when all jobs from the test and build stages pass. When the `UPLOAD_TO_S3` variable is non-zero, `make upload` is run. ```yaml stages: - test - build - package run_tests: stage: test script: - make test build_package: stage: build script: - make build upload_package: stage: package script: - if [ -n "${UPLOAD_TO_S3}" ]; then make upload; fi ``` You can then trigger a rebuild while you pass the `UPLOAD_TO_S3` variable and the script of the `upload_package` job will run: ```shell curl --request POST \ --form token=TOKEN \ --form ref=master \ --form "variables[UPLOAD_TO_S3]=true" \ https://gitlab.example.com/api/v4/projects/9/trigger/pipeline ``` Trigger variables have the [highest priority](../variables/README.md#priority-of-environment-variables) of all types of variables. ## Using cron to trigger nightly pipelines >**Note:** The following behavior can also be achieved through GitLab's UI with [pipeline schedules](../../user/project/pipelines/schedules.md). Whether you craft a script or just run cURL directly, you can trigger jobs in conjunction with cron. The example below triggers a job on the `master` branch of project with ID `9` every night at `00:30`: ```shell 30 0 * * * curl --request POST --form token=TOKEN --form ref=master https://gitlab.example.com/api/v4/projects/9/trigger/pipeline ``` ## Legacy triggers Old triggers, created before GitLab 9.0 will be marked as legacy. Triggers with the legacy label do not have an associated user and only have access to the current project. They are considered deprecated and will be removed with one of the future versions of GitLab. [ee-2017]: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/2017 [ee-2346]: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/2346 [ee]: https://about.gitlab.com/pricing/ [variables]: ../variables/README.md [predef]: ../variables/README.md#predefined-environment-variables [registry]: ../../user/packages/container_registry/index.md [permissions]: ../../user/permissions.md#job-permissions [trigapi]: ../../api/pipeline_triggers.md