Commit 219e37fd authored by Achilleas Pipinellis's avatar Achilleas Pipinellis

Merge branch 'docs-move-pips-merged-results' into 'master'

Docs: move content to its own doc

See merge request gitlab-org/gitlab-ce!30266
parents 792af55f ff0438fc
......@@ -81,6 +81,7 @@ GitLab CI/CD supports numerous configuration options:
| [Git submodules for CI/CD](git_submodules.md) | Configure jobs for using Git submodules.|
| [SSH keys for CI/CD](ssh_keys/README.md) | Using SSH keys in your CI pipelines. |
| [Pipelines triggers](triggers/README.md) | Trigger pipelines through the API. |
| [Pipelines for Merge Requests](merge_request_pipelines/index.md) | Design a pipeline structure for running a pipeline in merge requests. |
| [Integrate with Kubernetes clusters](../user/project/clusters/index.md) | Connect your project to Google Kubernetes Engine (GKE) or an existing Kubernetes cluster. |
| [GitLab Runner](https://docs.gitlab.com/runner/) | Configure your own GitLab Runners to execute your scripts. |
| [Optimize GitLab and Runner for large repositories](large_repositories/index.md) | Recommended strategies for handling large repos. |
......
---
type: reference
type: reference, index
last_update: 2019-07-03
---
# Pipelines for merge requests
# Pipelines for Merge Requests
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/15310) in GitLab 11.6.
......@@ -75,135 +76,13 @@ when a merge request was created or updated. For example:
![Merge request page](img/merge_request.png)
## Pipelines for merged results **[PREMIUM]**
## Pipelines for Merged Results **[PREMIUM]**
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/7380) in [GitLab Premium](https://about.gitlab.com/pricing/) 11.10.
> This feature is disabled by default until we resolve issues with [contention handling](https://gitlab.com/gitlab-org/gitlab-ee/issues/11222), but [can be enabled manually](#enabling-pipelines-for-merged-results).
Read the [documentation on Pipelines for Merged Results](pipelines_for_merged_results/index.md).
It's possible for your source and target branches to diverge, which can result
in the scenario that source branch's pipeline was green, the target's pipeline was green,
but the combined output fails.
### Merge Trains **[PREMIUM]**
By having your merge request pipeline automatically
create a new ref that contains the merge result of the source and target branch
(then running a pipeline on that ref), we can better test that the combined result
is also valid.
GitLab can run pipelines for merge requests
on this merged result. That is, where the source and target branches are combined into a
new ref and a pipeline for this ref validates the result prior to merging.
![Merge request pipeline as the head pipeline](img/merge_request_pipeline.png)
There are some cases where creating a combined ref is not possible or not wanted.
For example, a source branch that has conflicts with the target branch
or a merge request that is still in WIP status. In this case, the merge request pipeline falls back to a "detached" state
and runs on the source branch ref as if it was a regular pipeline.
The detached state serves to warn you that you are working in a situation
subjected to merge problems, and helps to highlight that you should
get out of WIP status or resolve merge conflicts as soon as possible.
### Requirements and limitations
Pipelines for merged results require:
- [GitLab Runner](https://gitlab.com/gitlab-org/gitlab-runner) 11.9 or newer.
- [Gitaly](https://gitlab.com/gitlab-org/gitaly) 1.21.0 or newer.
In addition, pipelines for merged results have the following limitations:
- Forking/cross-repo workflows are not currently supported. To follow progress,
see [#9713](https://gitlab.com/gitlab-org/gitlab-ee/issues/9713).
- This feature is not available for
[fast forward merges](../../user/project/merge_requests/fast_forward_merge.md) yet.
To follow progress, see [#58226](https://gitlab.com/gitlab-org/gitlab-ce/issues/58226).
### Enabling Pipelines for merged results
To enable pipelines on merged results at the project level:
1. Visit your project's **Settings > General** and expand **Merge requests**.
1. Check **Merge pipelines will try to validate the post-merge result prior to merging**.
1. Click **Save changes** button.
![Merge request pipeline config](img/merge_request_pipeline_config.png)
CAUTION: **Warning:**
Make sure your `gitlab-ci.yml` file is [configured properly for pipelines for merge requests](#configuring-pipelines-for-merge-requests),
otherwise pipelines for merged results won't run and your merge requests will be stuck in an unresolved state.
## Merge Trains **[PREMIUM]**
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/9186) in [GitLab Premium](https://about.gitlab.com/pricing/) 12.0.
> This feature is disabled by default, but [can be enabled manually](#enabling-merge-trains).
[Pipelines for merged results](#pipelines-for-merged-results-premium) introduces
running a build on the result of the merged code prior to merging, as a way to keep master green.
There's a scenario, however, for teams with a high number of changes in the target branch (typically master) where in many or even all cases,
by the time the merged code is validated another commit has made it to master, invalidating the merged result.
You'd need some kind of queuing, cancellation or retry mechanism for these scenarios
in order to ensure an orderly flow of changes into the target branch.
Each MR that joins a merge train joins as the last item in the train,
just as it works in the current state. However, instead of queuing and waiting,
each item takes the completed state of the previous (pending) merge ref, adds its own changes,
and starts the pipeline immediately in parallel under the assumption that everything is going to pass.
In this way, if all the pipelines in the train merge successfully, no pipeline time is wasted either queuing or retrying.
If the button is subsequently pressed in a different MR, instead of creating a new pipeline for the target branch,
it creates a new pipeline targeting the merge result of the previous MR plus the target branch.
Pipelines invalidated through failures are immediately canceled and requeued.
### Requirements and limitations
Merge trains have the following requirements and limitations:
- This feature requires that
[pipelines for merged results](#pipelines-for-merged-results-premium) are
**configured properly**.
- Each merge train can generate a merge ref and run a pipeline **one at a time**.
We plan to make the pipelines for merged results
[run in parallel](https://gitlab.com/gitlab-org/gitlab-ee/issues/11222) in a
future release.
### Enabling Merge Trains
To enable merge trains at the project level:
1. Visit your project's **Settings > General** and expand **Merge requests**.
1. Check **Allow merge trains**.
1. Click **Save changes** button.
![Merge request pipeline config](img/merge_train_config.png)
### How to add a merge request to a merge train
To add a merge request to a merge train:
1. Click "Start/Add merge train" button in a merge request
![Start merge train](img/merge_train_start.png)
### How to remove a merge request from a merge train
1. Click "Remove from merge train" button in the merge request widget.
![Cancel merge train](img/merge_train_cancel.png)
### Tips: Start/Add to merge train when pipeline succeeds
You can add a merge request to a merge train only when the latest pipeline in the
merge request finished. While the pipeline is running or pending, you cannot add
the merge request to a train because the current change of the merge request may
be broken thus it could affect the following merge requests.
In this case, you can schedule to add the merge request to a merge train **when the latest
pipeline succeeds**. You can see the following button instead of the regular "Start/Add merge train"
button while the latest pipeline is running.
![Add to merge train when pipeline succeeds](img/merge_train_start_when_pipeline_succeeds.png)
Read the [documentation on Merge Trains](pipelines_for_merged_results/merge_trains/index.md).
## Excluding certain jobs
......@@ -289,3 +168,15 @@ to integrate your job with [GitLab Merge Request API](../../api/merge_requests.m
You can find the list of available variables in [the reference sheet](../variables/predefined_variables.md).
The variable names begin with the `CI_MERGE_REQUEST_` prefix.
<!-- ## Troubleshooting
Include any troubleshooting steps that you can foresee. If you know beforehand what issues
one might have when setting this up, or when something is changed, or on upgrading, it's
important to describe those, too. Think of things that may go wrong and include them here.
This is important to minimize requests for support, and to avoid doc comments with
questions that you know someone might ask.
Each scenario can be a third-level heading, e.g. `### Getting error message X`.
If you have none to add when creating a doc, leave this section in place
but commented out to help encourage others to add to it in the future. -->
---
type: reference
last_update: 2019-07-03
---
# Pipelines for Merged Results **[PREMIUM]**
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/7380) in [GitLab Premium](https://about.gitlab.com/pricing/) 11.10.
> This feature is disabled by default until we resolve issues with [contention handling](https://gitlab.com/gitlab-org/gitlab-ee/issues/11222), but [can be enabled manually](#enabling-pipelines-for-merged-results).
It's possible for your source and target branches to diverge, which can result
in the scenario that source branch's pipeline was green, the target's pipeline was green,
but the combined output fails.
By having your merge request pipeline automatically
create a new ref that contains the merge result of the source and target branch
(then running a pipeline on that ref), we can better test that the combined result
is also valid.
GitLab can run pipelines for merge requests
on this merged result. That is, where the source and target branches are combined into a
new ref and a pipeline for this ref validates the result prior to merging.
![Merge request pipeline as the head pipeline](img/merge_request_pipeline.png)
There are some cases where creating a combined ref is not possible or not wanted.
For example, a source branch that has conflicts with the target branch
or a merge request that is still in WIP status. In this case, the merge request pipeline falls back to a "detached" state
and runs on the source branch ref as if it was a regular pipeline.
The detached state serves to warn you that you are working in a situation
subjected to merge problems, and helps to highlight that you should
get out of WIP status or resolve merge conflicts as soon as possible.
## Requirements and limitations
Pipelines for merged results require:
- [GitLab Runner](https://gitlab.com/gitlab-org/gitlab-runner) 11.9 or newer.
- [Gitaly](https://gitlab.com/gitlab-org/gitaly) 1.21.0 or newer.
In addition, pipelines for merged results have the following limitations:
- Forking/cross-repo workflows are not currently supported. To follow progress,
see [#9713](https://gitlab.com/gitlab-org/gitlab-ee/issues/9713).
- This feature is not available for
[fast forward merges](../../../user/project/merge_requests/fast_forward_merge.md) yet.
To follow progress, see [#58226](https://gitlab.com/gitlab-org/gitlab-ce/issues/58226).
## Enabling Pipelines for Merged Results
To enable pipelines on merged results at the project level:
1. Visit your project's **Settings > General** and expand **Merge requests**.
1. Check **Merge pipelines will try to validate the post-merge result prior to merging**.
1. Click **Save changes** button.
![Merge request pipeline config](img/merge_request_pipeline_config.png)
CAUTION: **Warning:**
Make sure your `gitlab-ci.yml` file is [configured properly for pipelines for merge requests](../index.md#configuring-pipelines-for-merge-requests),
otherwise pipelines for merged results won't run and your merge requests will be stuck in an unresolved state.
## Merge Trains **[PREMIUM]**
Read the [documentation on Merge Trains](merge_trains/index.md).
<!-- ## Troubleshooting
Include any troubleshooting steps that you can foresee. If you know beforehand what issues
one might have when setting this up, or when something is changed, or on upgrading, it's
important to describe those, too. Think of things that may go wrong and include them here.
This is important to minimize requests for support, and to avoid doc comments with
questions that you know someone might ask.
Each scenario can be a third-level heading, e.g. `### Getting error message X`.
If you have none to add when creating a doc, leave this section in place
but commented out to help encourage others to add to it in the future. -->
---
type: reference
last_update: 2019-07-03
---
# Merge Trains **[PREMIUM]**
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/9186) in [GitLab Premium](https://about.gitlab.com/pricing/) 12.0.
> This feature is disabled by default, but [can be enabled manually](#enabling-merge-trains).
[Pipelines for merged results](../index.md#pipelines-for-merged-results-premium) introduces
running a build on the result of the merged code prior to merging, as a way to keep master green.
There's a scenario, however, for teams with a high number of changes in the target branch (typically master) where in many or even all cases,
by the time the merged code is validated another commit has made it to master, invalidating the merged result.
You'd need some kind of queuing, cancellation or retry mechanism for these scenarios
in order to ensure an orderly flow of changes into the target branch.
Each MR that joins a merge train joins as the last item in the train,
just as it works in the current state. However, instead of queuing and waiting,
each item takes the completed state of the previous (pending) merge ref, adds its own changes,
and starts the pipeline immediately in parallel under the assumption that everything is going to pass.
In this way, if all the pipelines in the train merge successfully, no pipeline time is wasted either queuing or retrying.
If the button is subsequently pressed in a different MR, instead of creating a new pipeline for the target branch,
it creates a new pipeline targeting the merge result of the previous MR plus the target branch.
Pipelines invalidated through failures are immediately canceled and requeued.
## Requirements and limitations
Merge trains have the following requirements and limitations:
- This feature requires that
[pipelines for merged results](../index.md#pipelines-for-merged-results-premium) are
**configured properly**.
- Each merge train can generate a merge ref and run a pipeline **one at a time**.
We plan to make the pipelines for merged results
[run in parallel](https://gitlab.com/gitlab-org/gitlab-ee/issues/11222) in a
future release.
## Enabling Merge Trains
To enable merge trains at the project level:
1. Visit your project's **Settings > General** and expand **Merge requests**.
1. Check **Allow merge trains**.
1. Click **Save changes** button.
![Merge request pipeline config](img/merge_train_config_v12_0.png)
## How to add a merge request to a merge train
To add a merge request to a merge train:
1. Click "Start/Add merge train" button in a merge request
![Start merge train](img/merge_train_start_v12_0.png)
## How to remove a merge request from a merge train
1. Click "Remove from merge train" button in the merge request widget.
![Cancel merge train](img/merge_train_cancel_v12_0.png)
## Start/Add to merge train when pipeline succeeds
You can add a merge request to a merge train only when the latest pipeline in the
merge request finished. While the pipeline is running or pending, you cannot add
the merge request to a train because the current change of the merge request may
be broken thus it could affect the following merge requests.
In this case, you can schedule to add the merge request to a merge train **when the latest
pipeline succeeds**. You can see the following button instead of the regular "Start/Add merge train"
button while the latest pipeline is running.
![Add to merge train when pipeline succeeds](img/merge_train_start_when_pipeline_succeeds_v12_0.png)
<!-- ## Troubleshooting
Include any troubleshooting steps that you can foresee. If you know beforehand what issues
one might have when setting this up, or when something is changed, or on upgrading, it's
important to describe those, too. Think of things that may go wrong and include them here.
This is important to minimize requests for support, and to avoid doc comments with
questions that you know someone might ask.
Each scenario can be a third-level heading, e.g. `### Getting error message X`.
If you have none to add when creating a doc, leave this section in place
but commented out to help encourage others to add to it in the future. -->
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment