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diff --git a/doc/ci/merge_request_pipelines/pipelines_for_merged_results/merge_trains/index.md b/doc/ci/merge_request_pipelines/pipelines_for_merged_results/merge_trains/index.md index 57358434c02..80a1c264bc4 100644 --- a/doc/ci/merge_request_pipelines/pipelines_for_merged_results/merge_trains/index.md +++ b/doc/ci/merge_request_pipelines/pipelines_for_merged_results/merge_trains/index.md @@ -6,7 +6,6 @@ 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. @@ -33,35 +32,40 @@ 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. +- Each merge train can run a maximum of **four** pipelines in parallel. + If more than four merge requests are added to the merge train, the merge requests + will be queued until a slot in the merge train is free. There is no limit to the + number of merge requests that can be queued. +- This feature does not support [squash and merge](../../../../user/project/merge_requests/squash_and_merge.md). -## 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. - - +<i class="fa fa-youtube-play youtube" aria-hidden="true"></i> +Watch this video for a demonstration on [how parallel execution +of Merge Trains can prevent commits from breaking the default +branch](https://www.youtube.com/watch?v=D4qCqXgZkHQ). ## 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 +1. Visit a merge request. +1. Click the **Start/Add to merge train** button.  ## How to remove a merge request from a merge train -1. Click "Remove from merge train" button in the merge request widget. +1. Visit a merge request. +1. Click the **Remove from merge train** button.  +## How to view a merge request's current position on the merge train + +After a merge request has been added to the merge train, the merge request's +current position will be displayed under the pipeline widget: + + + ## 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 @@ -70,19 +74,71 @@ 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" +pipeline succeeds** (This pipeline is [Pipelines for merged results](../index.md), not Pipelines for merge train). +You can see the following button instead of the regular **Start/Add to merge train** button while the latest pipeline is running.  -<!-- ## Troubleshooting +## Immediately merge a merge request with a merge train + +In case, you have a high-priority merge request (e.g. critical patch) to be merged urgently, +you can use **Merge Immediately** option for bypassing the merge train. +This is the fastest option to get the change merged into the target branch. + + + +However, every time you merge a merge request immediately, it could affect the +existing merge train to be reconstructed, specifically, it regenerates expected +merge commits and pipelines. This means, merging immediately essentially wastes +CI resources. + +## Troubleshooting + +### Merge request dropped from the merge train immediately + +If a merge request is not mergeable (for example, it's WIP, there is a merge +conflict, etc), your merge request will be dropped from the merge train automatically. + +In these cases, the reason for dropping the merge request is in the **system notes**. + +To check the reason: + +1. Open the merge request that was dropped from the merge train. +1. Open the **Discussion** tab. +1. Find a system note that includes either: + - The text **... removed this merge request from the merge train because ...** + - **... aborted this merge request from the merge train because ...** + The reason is given in the text after the **because ...** phrase. + + + +### Merge When Pipeline Succeeds cannot be chosen + +[Merge When Pipeline Succeeds](../../../../user/project/merge_requests/merge_when_pipeline_succeeds.md) +is unavailable when +[Pipelines for Merged Results is enabled](../index.md#enabling-pipelines-for-merged-results). + +Follow [this issue](https://gitlab.com/gitlab-org/gitlab-ee/issues/12267) to +track progress on this issue. + +### Merge Train disturbs your workflow + +First of all, please check if [merge immediately](#immediately-merge-a-merge-request-with-a-merge-train) +is available as a workaround in your workflow. This is the most recommended +workaround you'd be able to take immediately. If it's not available or acceptable, +please read through this section. + +Merge train is enabled by default when you enable [Pipelines for merged results](../index.md), +however, you can forcibly disable this feature by disabling the feature flag `:merge_trains_enabled`. +After you disabled this feature, all the existing merge trains will be aborted and +you will no longer see the **Start/Add Merge Train** button in merge requests. -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. +To check if the feature flag is enabled on your GitLab instance, +please ask administrator to execute the following commands: -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. --> +```shell +> sudo gitlab-rails console # Login to Rails console of GitLab instance. +> Feature.enabled?(:merge_trains_enabled) # Check if it's enabled or not. +> Feature.disable(:merge_trains_enabled) # Disable the feature flag. +```
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