Auto-Generate GitHub Release Notes and Notify Slack with n8n

Enter repo info → fetch latest tag and merged PRs → group by label into Markdown draft → create GitHub draft release → Slack notification

Who

Open-source maintainers, DevOps engineers, and engineering teams needing structured release notes

You get

On manual trigger, generates label-grouped Markdown release notes from merged PRs, creates a GitHub draft release, and sends a summary to Slack

You need

n8n

Steps

1. Enter repository info via form

   When running the workflow in n8n, fill in the form: Repository Owner (GitHub user or org), Repository Name, and Branch Name (e.g., main). All three fields are required.

2. Config node extracts input and defines label grouping

   The Config node (Edit Fields/Set) maps form inputs to repoOwner, repoName, and defaultBranch, and defines labelMap and qaChecklist. labelMap determines how PR labels are mapped to release-note section headings; qaChecklist appends QA items at the end. Modify the mapping as needed.

3. Fetch latest tag and its commit date

   Call GitHub API `GET /repos/{owner}/{repo}/tags` to get the latest tag (authenticated with githubApi credentials), then follow that tag's commit.url to retrieve the exact commit timestamp. This timestamp sets the boundary for "since last release".

4. Query merged PRs after that timestamp

   Use the GitHub Search API: `is:pr is:merged repo:{owner}/{repo} base:{branch} merged:>={tag_commit_date}`. Results include PR titles, numbers, and label arrays for grouping.

5. Group by label and generate Markdown release notes

   A Code node runs JavaScript that reads labelMap and qaChecklist from the Config node, groups PRs by matched labels, and outputs formatted Markdown with sections and a QA Checklist. Unmatched PRs fall under "📋 Others".

   Execution prompt · Source text。n8n Code node 'Adjusted: Group PRs & Generate Release Notes' JS Code field

   Copy prompt

   // SAFELY access config node data
   const configNode = $('Config').first();
   if (!configNode) {
     throw new Error("Missing 'Config' node or it's not accessible.");
   }
   
   const labelMap =  configNode.labelMap|| {};
   const qaChecklist = configNode.qaChecklist || [];
   
   console.log("Your message", labelMap);
   console.log("Your message", qaChecklist);
   
   // Access PR list from previous node
   const prNode = $('Fetch All Merged PRs Since Last Tag').first(); // <-- Replace with your actual PR-fetch node name
   if (!prNode || !prNode.json || !Array.isArray(prNode.json.items)) {
     throw new Error("Pull request data not found or improperly formatted.");
   }
   
   const prItems = prNode.json.items;
   
   /** @type {Record<string, string[]>} */
   const grouped = {};
   
   // Loop through each PR
   for (const pr of prItems) {
     const labels = pr.labels?.map(l => l.name) || [];
     const matchedKey = labels.find(l => labelMap[l]);
     const groupTitle = matchedKey ? labelMap[matchedKey] : "📋 Others";
   
     if (!grouped[groupTitle]) {
       grouped[groupTitle] = [];
     }
   
     grouped[groupTitle].push(`- ${pr.title} (#${pr.number})`);
   }
   
   // Build Markdown content
   let markdown = `## 📝 Release Notes\n`;
   
   for (const group in grouped) {
     markdown += `\n### ${group}\n`;
     markdown += grouped[group].join("\n") + "\n";
   }
   
   markdown += `\n## ✅ QA Checklist\n`;
   markdown += qaChecklist.map(item => `[ ] ${item}`).join("\n");
   
   return [
     {
       json: {
         release_notes: markdown,
       },
     },
   ];

6. Create GitHub draft release and notify Slack

   The GitHub Pre-release node POSTs to `/repos/{owner}/{repo}/releases` with tag_name, name, body (the generated release_notes), draft=true, and prerelease=false. The Slack node then sends the release notes and release link to the configured channel. The Slack node's url field must be set to your actual Webhook URL.

You are setting up an n8n workflow that auto-generates draft release notes from merged GitHub PRs and posts to Slack. First confirm you have: 1) an accessible n8n instance; 2) a GitHub PAT or OAuth app with repo and write:repo_hook scopes; 3) a Slack Incoming Webhook URL or equivalent credential. Then import the workflow JSON, configure credentials, fill in the form fields, and trigger manually to test. If PRs lack labels, update the labelMap in the Config node or ensure PRs are labeled before merging.