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Downstream pipelines (FREE)
A downstream pipeline is any GitLab CI/CD pipeline triggered by another pipeline. Downstream pipelines run independently and concurrently to the upstream pipeline that triggered them.
- A parent-child pipeline is a downstream pipeline triggered in the same project as the first pipeline.
- A multi-project pipeline is a downstream pipeline triggered in a different project than the first pipeline.
You can sometimes use parent-child pipelines and multi-project pipelines for similar purposes, but there are key differences.
Parent-child pipelines
A parent pipeline is one that triggers a downstream pipeline in the same project. The downstream pipeline is called a child pipeline. Child pipelines:
- Run under the same project, ref, and commit SHA as the parent pipeline.
- Do not directly affect the overall status of the ref the pipeline runs against. For example,
if a pipeline fails for the main branch, it's common to say that "main is broken".
The status of child pipelines only affects the status of the ref if the child
pipeline is triggered with
strategy:depend
. - Are automatically canceled if the pipeline is configured with
interruptible
when a new pipeline is created for the same ref. - Are not displayed in the pipeline index page. You can only view child pipelines on their parent pipeline's page.
Nested child pipelines
- Introduced in GitLab 13.4.
- Feature flag removed in GitLab 13.5.
Parent and child pipelines were introduced with a maximum depth of one level of child pipelines, which was later increased to two. A parent pipeline can trigger many child pipelines, and these child pipelines can trigger their own child pipelines. It's not possible to trigger another level of child pipelines.
For an overview, see Nested Dynamic Pipelines.
Multi-project pipelines
A pipeline in one project can trigger downstream pipelines in another project, called multi-project pipelines. The user triggering the upstream pipeline must be able to start pipelines in the downstream project, otherwise the downstream pipeline fails to start.
For example, you might deploy your web application from three different GitLab projects. With multi-project pipelines you can trigger a pipeline in each project, where each has its own build, test, and deploy process. You can visualize the connected pipelines in one place, including all cross-project interdependencies.
Multi-project pipelines:
- Are triggered from another project's pipeline, but the upstream (triggering) pipeline does not have much control over the downstream (triggered) pipeline. However, it can choose the ref of the downstream pipeline, and pass CI/CD variables to it.
- Affect the overall status of the ref of the project it runs in, but does not
affect the status of the triggering pipeline's ref, unless it was triggered with
strategy:depend
. - Are not automatically canceled in the downstream project when using
interruptible
if a new pipeline runs for the same ref in the upstream pipeline. They can be automatically canceled if a new pipeline is triggered for the same ref on the downstream project. - Multi-project pipelines are standalone pipelines because they are normal pipelines that happened to be triggered by an external project. They are all visible on the pipeline index page.
- Are independent, so there are no nesting limits.
Learn more in the "Cross-project Pipeline Triggering and Visualization" demo at GitLab@learn, in the Continuous Integration section.
If you use a public project to trigger downstream pipelines in a private project, make sure there are no confidentiality problems. The upstream project's pipelines page always displays:
- The name of the downstream project.
- The status of the pipeline.
Trigger a downstream pipeline from a job in the .gitlab-ci.yml
file
Use the trigger
keyword in your .gitlab-ci.yml
file
to create a job that triggers a downstream pipeline. This job is called a trigger job.
After the trigger job starts, the initial status of the job is pending
while GitLab
attempts to create the downstream pipeline. If the downstream pipeline is created,
GitLab marks the job as passed, otherwise the job failed. Alternatively,
you can set the trigger job to show the downstream pipeline's status
instead.
For example:
::Tabs
:::TabTitle Multi-project pipeline
trigger_job:
trigger:
project: project-group/my-downstream-project
:::TabTitle Parent-child pipeline
trigger_job:
trigger:
include:
- local: path/to/child-pipeline.yml
::EndTabs
Use rules
to control downstream pipeline jobs
You can use CI/CD variables or the rules
keyword to
control job behavior for downstream pipelines.
When a downstream pipeline is triggered with the trigger
keyword,
the value of the $CI_PIPELINE_SOURCE
predefined variable
for all jobs is:
pipeline
for multi-project pipelines.parent
for parent-child pipelines.
For example, with a multi-project pipeline:
job1:
rules:
- if: $CI_PIPELINE_SOURCE == "pipeline"
script: echo "This job runs in multi-project pipelines only"
job2:
rules:
- if: $CI_PIPELINE_SOURCE == "merge_request_event"
script: echo "This job runs in merge request pipelines only"
job3:
rules:
- if: $CI_PIPELINE_SOURCE == "pipeline"
- if: $CI_PIPELINE_SOURCE == "merge_request_event"
script: echo "This job runs in both multi-project and merge request pipelines"
Specify a branch for multi-project pipelines
You can specify a branch name for a multi-project pipeline to use. GitLab uses the commit on the head of the branch to create the downstream pipeline:
rspec:
stage: test
script: bundle exec rspec
staging:
stage: deploy
trigger:
project: my/deployment
branch: stable-11-2
Use:
- The
project
keyword to specify the full path to a downstream project. In GitLab 15.3 and later, variable expansion is supported. - The
branch
keyword to specify the name of a branch in the project specified byproject
. In GitLab 12.4 and later, variable expansion is supported.
Use a child pipeline configuration file in a different project
Introduced in GitLab 13.5.
You can use include:file
to trigger child pipelines
with a configuration file in a different project:
microservice_a:
trigger:
include:
- project: 'my-group/my-pipeline-library'
ref: 'main'
file: '/path/to/child-pipeline.yml'
Combine multiple child pipeline configuration files
You can include up to three configuration files when defining a child pipeline. The child pipeline's configuration is composed of all configuration files merged together:
microservice_a:
trigger:
include:
- local: path/to/microservice_a.yml
- template: Security/SAST.gitlab-ci.yml
- project: 'my-group/my-pipeline-library'
ref: 'main'
file: '/path/to/child-pipeline.yml'
Dynamic child pipelines
Introduced in GitLab 12.9.
You can trigger a child pipeline from a YAML file generated in a job, instead of a static file saved in your project. This technique can be very powerful for generating pipelines targeting content that changed or to build a matrix of targets and architectures.
The artifact containing the generated YAML file must not be larger than 5MB.
For an overview, see Create child pipelines using dynamically generated configurations.
For an example project that generates a dynamic child pipeline, see
Dynamic Child Pipelines with Jsonnet.
This project shows how to use a data templating language to generate your .gitlab-ci.yml
at runtime.
You can use a similar process for other templating languages like
Dhall or ytt.
Trigger a dynamic child pipeline
To trigger a child pipeline from a dynamically generated configuration file:
- Generate the configuration file in a job and save it as an artifact:
generate-config:
stage: build
script: generate-ci-config > generated-config.yml
artifacts:
paths:
- generated-config.yml
- Configure the trigger job to run after the job that generated the configuration file,
and set
include: artifact
to the generated artifact:
child-pipeline:
stage: test
trigger:
include:
- artifact: generated-config.yml
job: generate-config
In this example, generated-config.yml
is extracted from the artifacts and used as the configuration
for triggering the child pipeline.
The artifact path is parsed by GitLab, not the runner, so the path must match the
syntax for the OS running GitLab. If GitLab is running on Linux but using a Windows
runner for testing, the path separator for the trigger job is /
. Other CI/CD
configuration for jobs that use the Windows runner, like scripts, use \
.
Run child pipelines with merge request pipelines
To trigger a child pipeline as a merge request pipeline:
-
Set the trigger job to run on merge requests:
# parent .gitlab-ci.yml microservice_a: trigger: include: path/to/microservice_a.yml rules: - if: $CI_PIPELINE_SOURCE == "merge_request_event"
-
Configure the child pipeline jobs to run in merge request pipelines:
-
With
workflow:rules
:# child path/to/microservice_a.yml workflow: rules: - if: $CI_PIPELINE_SOURCE == "merge_request_event" job1: script: ... job2: script: ...
-
By configuring rules for each job:
# child path/to/microservice_a.yml job1: script: ... rules: - if: $CI_PIPELINE_SOURCE == "merge_request_event" job2: script: ... rules: - if: $CI_PIPELINE_SOURCE == "merge_request_event"
-
Trigger a multi-project pipeline by using the API
You can use the CI/CD job token (CI_JOB_TOKEN
) with the
pipeline trigger API endpoint
to trigger multi-project pipelines from a CI/CD job. GitLab recognizes the source of the job token
and marks the pipelines as related. In the pipeline graph, the relationships are displayed
as inbound and outbound connections for upstream and downstream pipeline dependencies.
For example:
trigger_pipeline:
stage: deploy
script:
- curl --request POST --form "token=$CI_JOB_TOKEN" --form ref=main "https://gitlab.example.com/api/v4/projects/9/trigger/pipeline"
rules:
- if: $CI_COMMIT_TAG
environment: production
View a downstream pipeline
Hover behavior for pipeline cards introduced in GitLab 13.2.
In the pipeline graph view, downstream pipelines display as a list of cards on the right of the graph. Hover over the pipeline's card to view which job triggered the downstream pipeline.
Retry a downstream pipeline
- Retry from graph view introduced in GitLab 15.0 with a flag named
downstream_retry_action
. Disabled by default.- Retry from graph view generally available and feature flag removed in GitLab 15.1.
To retry a completed downstream pipeline, select Retry ({retry}):
- From the downstream pipeline's details page.
- On the pipeline's card in the pipeline graph view.
Cancel a downstream pipeline
- Retry from graph view introduced in GitLab 15.0 with a flag named
downstream_retry_action
. Disabled by default.- Retry from graph view generally available and feature flag removed in GitLab 15.1.
To cancel a downstream pipeline that is still running, select Cancel ({cancel}):
- From the downstream pipeline's details page.
- On the pipeline's card in the pipeline graph view.
Mirror the status of a downstream pipeline in the trigger job
You can mirror the pipeline status from the triggered pipeline to the source trigger job
by using strategy: depend
:
::Tabs
:::TabTitle Multi-project pipeline
trigger_job:
trigger:
project: my/project
strategy: depend
:::TabTitle Parent-child pipeline
trigger_job:
trigger:
include:
- local: path/to/child-pipeline.yml
strategy: depend
::EndTabs
View multi-project pipelines in pipeline graphs (PREMIUM)
When you trigger a multi-project pipeline, the downstream pipeline displays to the right of the pipeline graph.
In pipeline mini graphs, the downstream pipeline displays to the right of the mini graph.
Pass artifacts to a downstream pipeline
You can pass artifacts to a downstream pipeline by using needs:project
.
-
In a job in the upstream pipeline, save the artifacts using the
artifacts
keyword. -
Trigger the downstream pipeline with a trigger job:
build_artifacts: stage: build script: - echo "This is a test artifact!" >> artifact.txt artifacts: paths: - artifact.txt deploy: stage: deploy trigger: my/downstream_project
-
In a job in the downstream pipeline, fetch the artifacts from the upstream pipeline by using
needs:project
. Setjob
to the job in the upstream pipeline to fetch artifacts from,ref
to the branch, andartifacts: true
.test: stage: test script: - cat artifact.txt needs: - project: my/upstream_project job: build_artifacts ref: main artifacts: true
Pass artifacts from a Merge Request pipeline
When you use needs:project
to pass artifacts to a downstream pipeline,
the ref
value is usually a branch name, like main
or development
.
For merge request pipelines, the ref
value is in the form of refs/merge-requests/<id>/head
,
where id
is the merge request ID. You can retrieve this ref with the CI_MERGE_REQUEST_REF_PATH
CI/CD variable. Do not use a branch name as the ref
with merge request pipelines,
because the downstream pipeline attempts to fetch artifacts from the latest branch pipeline.
To fetch the artifacts from the upstream merge request
pipeline instead of the branch
pipeline,
pass this variable to the downstream pipeline using variable inheritance:
-
In a job in the upstream pipeline, save the artifacts using the
artifacts
keyword. -
In the job that triggers the downstream pipeline, pass the
$CI_MERGE_REQUEST_REF_PATH
variable by using variable inheritance:build_artifacts: stage: build script: - echo "This is a test artifact!" >> artifact.txt artifacts: paths: - artifact.txt upstream_job: variables: UPSTREAM_REF: $CI_MERGE_REQUEST_REF_PATH trigger: project: my/downstream_project branch: my-branch
-
In a job in the downstream pipeline, fetch the artifacts from the upstream pipeline by using
needs:project
. Set theref
to theUPSTREAM_REF
variable, andjob
to the job in the upstream pipeline to fetch artifacts from:test: stage: test script: - cat artifact.txt needs: - project: my/upstream_project job: build_artifacts ref: $UPSTREAM_REF artifacts: true
This method works for fetching artifacts from a regular merge request parent pipeline, but fetching artifacts from merge results pipelines is not supported.
Pass CI/CD variables to a downstream pipeline
You can pass CI/CD variables to a downstream pipeline with a few different methods, based on where the variable is created or defined.
Pass YAML-defined CI/CD variables
You can use the variables
keyword to pass CI/CD variables to a downstream pipeline,
just like you would for any other job.
For example, in a multi-project pipeline:
rspec:
stage: test
script: bundle exec rspec
staging:
variables:
ENVIRONMENT: staging
stage: deploy
trigger: my/deployment
The ENVIRONMENT
variable is passed to every job defined in a downstream
pipeline. It is available as a variable when GitLab Runner picks a job.
In the following configuration, the MY_VARIABLE
variable is passed to the downstream pipeline
that is created when the trigger-downstream
job is queued. This behavior is because trigger-downstream
job inherits variables declared in global variables
blocks,
and then GitLab passes these variables to the downstream pipeline.
variables:
MY_VARIABLE: my-value
trigger-downstream:
variables:
ENVIRONMENT: something
trigger: my/project
Prevent global variables from being passed
You can stop global variables from reaching the downstream pipeline by using the inherit:variables
keyword.
For example, in a multi-project pipeline:
variables:
MY_GLOBAL_VAR: value
trigger-downstream:
inherit:
variables: false
variables:
MY_LOCAL_VAR: value
trigger: my/project
In this example, the MY_GLOBAL_VAR
variable is not available in the triggered pipeline.
Pass a predefined variable
You might want to pass some information about the upstream pipeline using predefined variables. To do that, you can use interpolation to pass any variable. For example, in a multi-project pipeline:
downstream-job:
variables:
UPSTREAM_BRANCH: $CI_COMMIT_REF_NAME
trigger: my/project
In this scenario, the UPSTREAM_BRANCH
variable with the value of the upstream pipeline's
$CI_COMMIT_REF_NAME
is passed to downstream-job
. It is available in the
context of all downstream builds.
You cannot use this method to forward job-level persisted variables to a downstream pipeline, as they are not available in trigger jobs.
Upstream pipelines take precedence over downstream ones. If there are two variables with the same name defined in both upstream and downstream projects, the ones defined in the upstream project take precedence.
Pass dotenv variables created in a job (PREMIUM)
You can pass variables to a downstream pipeline with dotenv
variable inheritance
and needs:project
.
For example, in a multi-project pipeline:
-
Save the variables in a
.env
file. -
Save the
.env
file as adotenv
report. -
Trigger the downstream pipeline.
build_vars: stage: build script: - echo "BUILD_VERSION=hello" >> build.env artifacts: reports: dotenv: build.env deploy: stage: deploy trigger: my/downstream_project
-
Set the
test
job in the downstream pipeline to inherit the variables from thebuild_vars
job in the upstream project withneeds
. Thetest
job inherits the variables in thedotenv
report and it can accessBUILD_VERSION
in the script:test: stage: test script: - echo $BUILD_VERSION needs: - project: my/upstream_project job: build_vars ref: master artifacts: true
Troubleshooting
Trigger job fails and does not create multi-project pipeline
With multi-project pipelines, the trigger job fails and does not create the downstream pipeline if:
- The downstream project is not found.
- The user that creates the upstream pipeline does not have permission to create pipelines in the downstream project.
- The downstream pipeline targets a protected branch and the user does not have permission to run pipelines against the protected branch. See pipeline security for protected branches for more information.