GitLab MR analysis: docs, tests, optimization

Example workflows (ready to adapt) – GitLab MR analysis: docs, tests, optimization

This workflow automates GitLab Merge Request (MR) analysis by generating code documentation, unit tests, and optimization suggestions for each changed file. After processing, it posts a consolidated report as an MR comment and notifies your team in Slack. You can adapt this template to fit your project’s needs.

Workflow Diagram

A high-level flowchart of the MR analysis process:

flowchart TD
  A[GitLab MR Trigger] --> B[Filter MR Opened]
  B --> C{Get MR Data}
  C -->|Commits| D[Get MR Commits]
  C -->|Changes| E[Get MR Changes]
  E --> F[Process Changed Files]
  F --> G[Get File Content]
  G --> H[Prepare File Data]
  H --> I1[Generate Documentation]
  H --> I2[Generate Tests]
  H --> I3[Generate Optimization]
  I1 & I2 & I3 --> J[Combine Analysis]
  J --> K[Post MR Comment]
  K --> L[Notify Team via Slack]

Nodes & Responsibilities

Node Type Purpose
GitLab MR Trigger GitLab Trigger – merge_requests Listens for new or updated MRs in your GitLab project
Filter MR Opened If Ensures only opened MRs are processed
Get MR Commits GitLab – getCommits Fetches the commit history for the MR
Get MR Changes GitLab – getChanges Retrieves the list of files changed in the MR
Process Changed Files Function – code Extracts file metadata (path, new vs. modified, diff) and limits processing to a configurable number of files
Get File Content GitLab – getFile Downloads the raw file content from the source branch
Prepare File Data Function – code Decodes Base64 content, labels new vs. modified, and attaches MR context (project ID, MR IID)
Generate Documentation DocuWriter.ai – codeDocumentation Uses AI to generate comprehensive technical docs for the file
Generate Tests DocuWriter.ai – codeTests Produces unit test stubs or suggestions based on source code
Generate Optimization DocuWriter.ai – codeOptimization Proposes code improvements (performance, readability, security)
Combine Analysis Function – code Aggregates docs, tests, and optimization into a single Markdown report
Post MR Comment GitLab – createNote Posts the combined report as a comment on the MR
Notify Team via Slack Slack – postMessage Sends a Slack message with MR title, author, branches, and a link to view the report in GitLab

Key Configuration Snippet

{
  "name": "GitLab MR Documentation & Analysis",
  "nodes": [
    {
      "id": "gitlab-mr-trigger",
      "type": "n8n-nodes-base.gitlabTrigger",
      "parameters": { "events": ["merge_requests"] },
      "credentials": { "gitlabApi": { "name": "GitLab API" } }
    },
    {
      "id": "filter-mr-opened",
      "type": "n8n-nodes-base.if",
      "parameters": {
        "conditions": {
          "string": [
            {
              "value1": "={{$json.object_attributes.action}}",
              "operation": "equal",
              "value2": "open"
            }
          ]
        }
      }
    },
    {
      "id": "get-mr-commits",
      "type": "n8n-nodes-base.gitlab",
      "parameters": {
        "resource": "mergeRequest",
        "operation": "getCommits",
        "projectId": "={{$json.project.id}}",
        "mergeRequestIid": "={{$json.object_attributes.iid}}"
      }
    },
    {
      "id": "prepare-file-data",
      "type": "n8n-nodes-base.code",
      "parameters": {
        "jsCode": "// Decode and prepare source code..."
      }
    },
    {
      "id": "generate-documentation",
      "type": "n8n-nodes-docuwriter-ai.docuWriter",
      "parameters": {
        "resource": "codeDocumentation",
        "operation": "generate"
      },
      "credentials": { "docuWriterApi": { "name": "DocuWriter.ai API" } }
    },
    {
      "id": "generate-tests",
      "type": "n8n-nodes-docuwriter-ai.docuWriter",
      "parameters": {
        "resource": "codeTests",
        "operation": "generate"
      }
    },
    {
      "id": "generate-optimization",
      "type": "n8n-nodes-docuwriter-ai.docuWriter",
      "parameters": {
        "resource": "codeOptimization",
        "operation": "optimize"
      }
    },
    {
      "id": "combine-analysis",
      "type": "n8n-nodes-base.code",
      "parameters": {
        "jsCode": "// Combine docs, tests & optimizations..."
      }
    },
    {
      "id": "post-mr-comment",
      "type": "n8n-nodes-base.gitlab",
      "parameters": {
        "resource": "mergeRequest",
        "operation": "createNote"
      }
    },
    {
      "id": "notify-team",
      "type": "n8n-nodes-base.slack",
      "parameters": {
        "channel": "#code-reviews",
        "text": "🔍 Code analysis complete for GitLab MR"
      }
    }
  ]
}

(Adapt node IDs, branches, and credentials to your environment.)

Adapting the Workflow

  • 🔧 Adjust Limits: Modify Process Changed Files to analyze more or fewer files.
  • 🌐 Customize Channels: Change Slack channels or add email notifications.
  • 📋 Refine AI Prompts: Tweak additionalInstructions in DocuWriter.ai nodes to suit your project style.
  • 🔒 Secure Tokens: Ensure GitLab and DocuWriter.ai credentials are correctly stored in n8n.

Use this robust template to kickstart automated MR reviews in your GitLab projects!

Updated