112 lines
4.6 KiB
Markdown
112 lines
4.6 KiB
Markdown
---
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stage: Foundations
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group: Import and Integrate
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info: Any user with at least the Maintainer role can merge updates to this content. For details, see https://docs.gitlab.com/ee/development/development_processes.html#development-guidelines-review.
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title: Group migration by direct transfer
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---
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{{< alert type="note" >}}
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To use direct transfer, ensure your GitLab installation is accessible from
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[GitLab IP addresses](../user/gitlab_com/_index.md#ip-range) and has a public DNS entry.
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{{< /alert >}}
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[Group migration by direct transfer](../user/group/import/_index.md) is the
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evolution of migrating groups and projects using file exports. The goal is to have an easier way for the user to migrate a whole group,
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including projects, from one GitLab instance to another.
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## Design decisions
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The following architectural diagram illustrates how the Group Migration
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works with a set of [ETL](#etl) Pipelines leveraging from the current [GitLab APIs](#api).
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### ETL
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<!-- Direct quote from the IBM URL link -->
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> ETL, for extract, transform and load, is a data integration process that
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> combines data from multiple data sources into a single, consistent data store
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> that is loaded into a data warehouse or other target system.
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Using [ETL](https://www.ibm.com/think/topics/etl) architecture makes the code more explicit and easier to follow, test and extend. The
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idea is to have one ETL pipeline for each relation to be imported.
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### API
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The current [project](../user/project/settings/import_export.md#migrate-projects-by-uploading-an-export-file) and
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[group](../user/project/settings/import_export.md#migrate-groups-by-uploading-an-export-file-deprecated) imports are file based, so
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they require an export step to generate the file to be imported.
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Group migration by direct transfer leverages the [GitLab API](../api/rest/_index.md) to speed the migration.
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And, because we're on the road to [GraphQL](../api/graphql/_index.md),
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Group migration by direct transfer can contribute to expanding GraphQL API coverage, which benefits both GitLab
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and its users.
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### Namespace
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The migration process starts with the creation of a [`BulkImport`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/models/bulk_import.rb)
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record to keep track of the migration. From there all the code related to the
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GitLab Group Migration can be found under the new `BulkImports` namespace in all the application layers.
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### Idempotency
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To ensure we don't get duplicate entries when re-running the same Sidekiq job, we cache each entry as it's processed and skip entries if they're present in the cache.
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There are two different strategies:
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- `BulkImports::Pipeline::HexdigestCacheStrategy`, which caches a hexdigest representation of the data.
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- `BulkImports::Pipeline::IndexCacheStrategy`, which caches the last processed index of an entry in a pipeline.
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### Sidekiq jobs execution hierarchy
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**On destination instance**
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```mermaid
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flowchart TD
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subgraph s1["Main"]
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BulkImportWorker -- Enqueue itself --> BulkImportWorker
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BulkImportWorker --> BulkImports::ExportRequestWorker
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BulkImports::ExportRequestWorker --> BulkImports::EntityWorker
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BulkImports::EntityWorker -- Enqueue itself --> BulkImports::EntityWorker
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BulkImports::EntityWorker --> BulkImports::PipelineWorker
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BulkImports::PipelineWorker -- Enqueue itself --> BulkImports::PipelineWorker
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BulkImports::EntityWorker --> BulkImports::PipelineWorkerA["BulkImports::PipelineWorker"]
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BulkImports::EntityWorker --> BulkImports::PipelineWorkerA1["..."]
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BulkImportWorker --> BulkImports::ExportRequestWorkerB["BulkImports::ExportRequestWorker"]
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BulkImports::ExportRequestWorkerB --> BulkImports::PipelineWorkerBB["..."]
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end
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subgraph s2["Batched pipelines"]
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BulkImports::PipelineWorker --> BulkImports::PipelineBatchWorker
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BulkImports::PipelineWorker --> BulkImports::PipelineBatchWorkerA["..."]
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BulkImports::PipelineBatchWorker --> BulkImports::FinishBatchedPipelineWorker
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end
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```
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```mermaid
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flowchart TD
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subgraph s1["Cron"]
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BulkImports::StaleImportWorker
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end
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```
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**On source instance**
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```mermaid
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flowchart TD
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subgraph s1["Main"]
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BulkImports::RelationExportWorker
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end
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subgraph s2["Batched relations"]
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BulkImports::RelationExportWorker --> BulkImports::RelationBatchExportWorker
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BulkImports::RelationExportWorker --> BulkImports::RelationBatchExportWorkerA["..."]
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BulkImports::RelationBatchExportWorker --> BulkImports::FinishBatchedRelationExportWorker
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end
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```
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