This workflow follows the HTTP Request → Slack recipe pattern — see all workflows that pair these two integrations.
The workflow JSON
Copy or download the full n8n JSON below. Paste it into a new n8n workflow, add your credentials, activate. Full import guide →
{
"name": "GitLab MR Code Review",
"nodes": [
{
"parameters": {
"rule": {
"interval": [
{
"field": "minutes",
"minutesInterval": 1
}
]
}
},
"id": "schedule",
"name": "Every Minute",
"type": "n8n-nodes-base.scheduleTrigger",
"typeVersion": 1.2,
"position": [
416,
304
]
},
{
"parameters": {
"method": "GET",
"url": "=https://__GITLAB_HOST__/api/v4/projects/{{ encodeURIComponent('__GITLAB_PROJECT__') }}/merge_requests",
"authentication": "genericCredentialType",
"genericAuthType": "httpHeaderAuth",
"sendQuery": true,
"queryParameters": {
"parameters": [
{
"name": "state",
"value": "opened"
},
{
"name": "per_page",
"value": "20"
},
{
"name": "order_by",
"value": "updated_at"
},
{
"name": "sort",
"value": "desc"
}
]
},
"options": {}
},
"id": "get-mrs",
"name": "Get Open MRs",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
608,
304
],
"credentials": {
"httpHeaderAuth": {
"name": "<your credential>"
}
}
},
{
"parameters": {
"jsCode": "const CONFIG = { GITLAB_HOST: '__GITLAB_HOST__', GITLAB_PROJECT: '__GITLAB_PROJECT__' };\nconst mrs = $input.all().map(i => i.json);\n\nconst toReview = mrs.filter(mr => {\n const labels = mr.labels || [];\n const hasInProgress = labels.includes('ai-review::in-progress');\n const reviewedSha = labels.find(l => l.startsWith('ai-review::sha:'))?.replace('ai-review::sha:', '');\n return !hasInProgress && reviewedSha !== mr.sha;\n});\n\nif (toReview.length === 0) return [];\n\nconst mr = toReview[0];\nreturn [{\n json: {\n mr_iid: mr.iid,\n mr_title: mr.title,\n mr_url: mr.web_url,\n source_branch: mr.source_branch,\n target_branch: mr.target_branch,\n author: mr.author?.username,\n project_path: CONFIG.GITLAB_PROJECT,\n gitlab_host: CONFIG.GITLAB_HOST,\n sha: mr.sha,\n reviewers: (mr.reviewers || []).map(r => r.username),\n labels: mr.labels || []\n }\n}];"
},
"id": "filter-mrs",
"name": "Filter",
"type": "n8n-nodes-base.code",
"typeVersion": 2,
"position": [
784,
304
]
},
{
"parameters": {
"method": "PUT",
"url": "=https://{{ $json.gitlab_host }}/api/v4/projects/{{ encodeURIComponent($json.project_path) }}/merge_requests/{{ $json.mr_iid }}",
"authentication": "genericCredentialType",
"genericAuthType": "httpHeaderAuth",
"sendBody": true,
"specifyBody": "json",
"jsonBody": "={{ JSON.stringify({ add_labels: 'ai-review::in-progress', remove_labels: $json.labels.filter(l => l.startsWith('ai-review::')).join(',') || undefined }) }}",
"options": {}
},
"id": "label-in-progress",
"name": "In Progress",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
960,
304
],
"credentials": {
"httpHeaderAuth": {
"name": "<your credential>"
}
},
"onError": "continueRegularOutput"
},
{
"parameters": {
"method": "GET",
"url": "=https://{{ $('Filter').first().json.gitlab_host }}/api/v4/projects/{{ encodeURIComponent($('Filter').first().json.project_path) }}/merge_requests/{{ $('Filter').first().json.mr_iid }}/discussions",
"authentication": "genericCredentialType",
"genericAuthType": "httpHeaderAuth",
"options": {}
},
"id": "get-discussions",
"name": "Get Discussions",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
1152,
304
],
"credentials": {
"httpHeaderAuth": {
"name": "<your credential>"
}
},
"onError": "continueRegularOutput"
},
{
"parameters": {
"jsCode": "const AI_MARKER = 'AI Code Review';\nconst mr = $('Filter').first().json;\nconst discussions = $input.all().map(i => i.json);\n\nconst threads = [];\nfor (const d of discussions) {\n const notes = d.notes || [];\n if (notes.length === 0) continue;\n \n const isAI = n => (n.body || '').split('\\n')[0].includes(AI_MARKER);\n const isUser = n => !n.system && !isAI(n);\n \n if (notes.some(isAI) && !notes.some(isUser)) continue;\n \n const thread = { notes: [], position: null };\n for (const note of notes) {\n if (note.system) continue;\n thread.notes.push({ author: note.author?.username, body: (note.body || '').slice(0, 500), isAI: isAI(note) });\n if (note.type === 'DiffNote' && note.position && !thread.position) {\n thread.position = { file: note.position.new_path || note.position.old_path, line: note.position.new_line || note.position.old_line };\n }\n }\n if (thread.notes.length > 0) threads.push(thread);\n}\n\nreturn { json: { ...mr, threads } };"
},
"id": "process-notes",
"name": "Process Notes",
"type": "n8n-nodes-base.code",
"typeVersion": 2,
"position": [
1328,
304
]
},
{
"parameters": {
"jsCode": "const mr = $input.first().json;\nconst threads = mr.threads || [];\n\nlet prompt = `Review MR !${mr.mr_iid}: ${mr.mr_title}\\n\\n**Branch**: \\`${mr.source_branch}\\` \u2192 \\`${mr.target_branch}\\`\\n**Author**: ${mr.author}\\n**URL**: ${mr.mr_url}`;\n\nif (threads.length > 0) {\n prompt += '\\n\\n## Discussion Threads';\n for (const thread of threads) {\n prompt += thread.position ? `\\n\\n### \\`${thread.position.file}:${thread.position.line}\\`` : '\\n\\n### General Discussion';\n for (const n of thread.notes) {\n prompt += `\\n- ${n.isAI ? '\ud83e\udd16 AI' : `@${n.author}`}: \"${n.body}\"`;\n }\n }\n}\n\nreturn { json: { ...mr, formatted_message: prompt } };"
},
"id": "build-prompt",
"name": "Build Prompt",
"type": "n8n-nodes-base.code",
"typeVersion": 2,
"position": [
1504,
304
]
},
{
"parameters": {
"method": "POST",
"url": "={{ $env.N8N_API_URL }}/v1/projects/system/chat",
"sendBody": true,
"specifyBody": "json",
"jsonBody": "={{ JSON.stringify({ user_message: $json.formatted_message, agent: 'MR Reviewer', source: 'gitlab', requester: 'gitlab-mr-workflow', metadata: { mr_iid: $json.mr_iid, mr_url: $json.mr_url, author: $json.author, source_branch: $json.source_branch, target_branch: $json.target_branch, workflow_execution_id: $executionId } }) }}",
"options": {
"timeout": 660000
}
},
"id": "execute-claude",
"name": "Execute",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
1680,
304
],
"onError": "continueRegularOutput"
},
{
"parameters": {
"conditions": {
"options": {
"caseSensitive": true,
"leftValue": "",
"typeValidation": "strict"
},
"conditions": [
{
"id": "success",
"leftValue": "={{ $json.status }}",
"rightValue": "completed",
"operator": {
"type": "string",
"operation": "equals"
}
}
],
"combinator": "and"
},
"options": {}
},
"id": "check-result",
"name": "Success?",
"type": "n8n-nodes-base.if",
"typeVersion": 2,
"position": [
1856,
304
]
},
{
"parameters": {
"jsCode": "const mr = $('Build Prompt').item.json;\nconst result = $('Execute').item.json;\nconst output = result.structured_output || {};\n\nconst review = {\n verdict: output.verdict || 'comment',\n gitlab_comment: output.gitlab_comment || '## \ud83d\udd0d AI Code Review\\n\\nReview completed.',\n summary: output.summary || '\ub9ac\ubdf0 \uc644\ub8cc',\n points: output.points || []\n};\n\nreturn { json: { mr, review, reviewers: mr.reviewers || [] } };"
},
"id": "parse-review",
"name": "Parse Review",
"type": "n8n-nodes-base.code",
"typeVersion": 2,
"position": [
2032,
208
]
},
{
"parameters": {
"method": "POST",
"url": "=https://{{ $json.mr.gitlab_host }}/api/v4/projects/{{ encodeURIComponent($json.mr.project_path) }}/merge_requests/{{ $json.mr.mr_iid }}/notes",
"authentication": "genericCredentialType",
"genericAuthType": "httpHeaderAuth",
"sendBody": true,
"specifyBody": "json",
"jsonBody": "={{ JSON.stringify({ body: $json.review.gitlab_comment }) }}",
"options": {}
},
"id": "post-gitlab-comment",
"name": "Post GitLab Comment",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
2208,
208
],
"credentials": {
"httpHeaderAuth": {
"name": "<your credential>"
}
},
"onError": "continueRegularOutput"
},
{
"parameters": {
"jsCode": "const data = $('Parse Review').item.json;\nconst mr = data.mr;\nconst review = data.review;\nconst reviewers = data.reviewers || [];\nconst dashboardUrl = $env.N8N_DASHBOARD_URL;\n\n// Verdict emoji\nconst verdictEmoji = { approve: ':white_check_mark:', request_changes: ':warning:', comment: ':speech_balloon:' };\nconst emoji = verdictEmoji[review.verdict] || ':speech_balloon:';\n\n// Build message parts\nconst header = `${emoji} <${mr.mr_url}|!${mr.mr_iid}> ${mr.mr_title}`;\nconst summary = review.summary;\nconst points = (review.points || []).map(p => `\u2022 ${p}`).join('\\n');\n\n// Reviewer mentions\nconst mentions = [];\nfor (const username of reviewers) {\n if (!username) continue;\n try {\n const res = await this.helpers.httpRequest({ method: 'GET', url: `${dashboardUrl}/api/plugins/slack/users`, qs: { q: username, limit: 1 } });\n if (res.users?.[0]) mentions.push(`<@${res.users[0].id}>`);\n } catch (e) {}\n}\n\n// Assemble final message\nlet message = header + '\\n' + summary;\nif (points) message += '\\n' + points;\nif (mentions.length > 0) message += '\\n' + mentions.join(' ');\n\nreturn { json: { message, mr, review } };"
},
"id": "build-message",
"name": "Build Message",
"type": "n8n-nodes-base.code",
"typeVersion": 2,
"position": [
2384,
208
]
},
{
"parameters": {
"select": "channel",
"channelId": {
"__rl": true,
"mode": "id",
"value": "__MR_REVIEW_CHANNEL__"
},
"text": "={{ $json.message }}",
"otherOptions": {
"includeLinkToWorkflow": false
}
},
"id": "post-slack",
"name": "Post Slack",
"type": "n8n-nodes-base.slack",
"typeVersion": 2.2,
"position": [
2576,
208
],
"credentials": {
"slackApi": {
"name": "<your credential>"
}
}
},
{
"parameters": {
"method": "PUT",
"url": "=https://{{ $('Build Prompt').item.json.gitlab_host }}/api/v4/projects/{{ encodeURIComponent($('Build Prompt').item.json.project_path) }}/merge_requests/{{ $('Build Prompt').item.json.mr_iid }}",
"authentication": "genericCredentialType",
"genericAuthType": "httpHeaderAuth",
"sendBody": true,
"specifyBody": "json",
"jsonBody": "={{ JSON.stringify({ add_labels: 'ai-review::done,ai-review::sha:' + $('Build Prompt').item.json.sha, remove_labels: 'ai-review::in-progress' }) }}",
"options": {}
},
"id": "label-done",
"name": "Done",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
2752,
208
],
"credentials": {
"httpHeaderAuth": {
"name": "<your credential>"
}
},
"onError": "continueRegularOutput"
},
{
"parameters": {
"method": "POST",
"url": "={{ $env.N8N_API_URL }}/v1/workflows/stats",
"sendBody": true,
"specifyBody": "json",
"jsonBody": "={{ JSON.stringify({ workflow: 'gitlab-mr-review', execution_id: $('Execute').item.json.id, status: 'success', duration_ms: $('Execute').item.json.duration_ms, metadata: { mr_iid: $('Build Prompt').item.json.mr_iid, mr_title: $('Build Prompt').item.json.mr_title } }) }}",
"options": {
"timeout": 5000
}
},
"id": "record-stats-ok",
"name": "Stats OK",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
2928,
208
],
"onError": "continueRegularOutput"
},
{
"parameters": {
"method": "PUT",
"url": "=https://{{ $('Build Prompt').item.json.gitlab_host }}/api/v4/projects/{{ encodeURIComponent($('Build Prompt').item.json.project_path) }}/merge_requests/{{ $('Build Prompt').item.json.mr_iid }}",
"authentication": "genericCredentialType",
"genericAuthType": "httpHeaderAuth",
"sendBody": true,
"specifyBody": "json",
"jsonBody": "={{ JSON.stringify({ add_labels: 'ai-review::failed', remove_labels: 'ai-review::in-progress' }) }}",
"options": {}
},
"id": "label-failed",
"name": "Failed",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
2032,
400
],
"credentials": {
"httpHeaderAuth": {
"name": "<your credential>"
}
},
"onError": "continueRegularOutput"
},
{
"parameters": {
"select": "channel",
"channelId": {
"__rl": true,
"mode": "id",
"value": "__MR_REVIEW_CHANNEL__"
},
"text": "={{ `:x: *MR Review Failed*\\n<${$('Build Prompt').item.json.mr_url}|!${$('Build Prompt').item.json.mr_iid}> ${$('Build Prompt').item.json.mr_title}\\n${$('Success?').item.json.status === 'timeout' ? ':hourglass: Timeout' : ':warning: ' + ($('Success?').item.json.error?.message || 'Unknown error')}` }}",
"otherOptions": {
"includeLinkToWorkflow": false
}
},
"id": "notify-failure",
"name": "Notify Failure",
"type": "n8n-nodes-base.slack",
"typeVersion": 2.2,
"position": [
2208,
400
],
"credentials": {
"slackApi": {
"name": "<your credential>"
}
}
},
{
"parameters": {
"method": "POST",
"url": "={{ $env.N8N_API_URL }}/v1/workflows/stats",
"sendBody": true,
"specifyBody": "json",
"jsonBody": "={{ JSON.stringify({ workflow: 'gitlab-mr-review', execution_id: $('Execute').item.json.id, status: $('Success?').item.json.status === 'timeout' ? 'timeout' : 'error', duration_ms: $('Execute').item.json.duration_ms, metadata: { mr_iid: $('Build Prompt').item.json.mr_iid, error: $('Success?').item.json.error?.message } }) }}",
"options": {
"timeout": 5000
}
},
"id": "record-stats-err",
"name": "Stats Err",
"type": "n8n-nodes-base.httpRequest",
"typeVersion": 4.2,
"position": [
2384,
400
],
"onError": "continueRegularOutput"
}
],
"connections": {
"Every Minute": {
"main": [
[
{
"node": "Get Open MRs",
"type": "main",
"index": 0
}
]
]
},
"Get Open MRs": {
"main": [
[
{
"node": "Filter",
"type": "main",
"index": 0
}
]
]
},
"Filter": {
"main": [
[
{
"node": "In Progress",
"type": "main",
"index": 0
}
]
]
},
"In Progress": {
"main": [
[
{
"node": "Get Discussions",
"type": "main",
"index": 0
}
]
]
},
"Get Discussions": {
"main": [
[
{
"node": "Process Notes",
"type": "main",
"index": 0
}
]
]
},
"Process Notes": {
"main": [
[
{
"node": "Build Prompt",
"type": "main",
"index": 0
}
]
]
},
"Build Prompt": {
"main": [
[
{
"node": "Execute",
"type": "main",
"index": 0
}
]
]
},
"Execute": {
"main": [
[
{
"node": "Success?",
"type": "main",
"index": 0
}
]
]
},
"Success?": {
"main": [
[
{
"node": "Parse Review",
"type": "main",
"index": 0
}
],
[
{
"node": "Failed",
"type": "main",
"index": 0
}
]
]
},
"Parse Review": {
"main": [
[
{
"node": "Post GitLab Comment",
"type": "main",
"index": 0
}
]
]
},
"Post GitLab Comment": {
"main": [
[
{
"node": "Build Message",
"type": "main",
"index": 0
}
]
]
},
"Build Message": {
"main": [
[
{
"node": "Post Slack",
"type": "main",
"index": 0
}
]
]
},
"Post Slack": {
"main": [
[
{
"node": "Done",
"type": "main",
"index": 0
}
]
]
},
"Done": {
"main": [
[
{
"node": "Stats OK",
"type": "main",
"index": 0
}
]
]
},
"Failed": {
"main": [
[
{
"node": "Notify Failure",
"type": "main",
"index": 0
}
]
]
},
"Notify Failure": {
"main": [
[
{
"node": "Stats Err",
"type": "main",
"index": 0
}
]
]
}
},
"settings": {
"executionOrder": "v1",
"callerPolicy": "workflowsFromSameOwner",
"availableInMCP": false
}
}
Credentials you'll need
Each integration node will prompt for credentials when you import. We strip credential IDs before publishing — you'll add your own.
httpHeaderAuthslackApi
Pro
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About this workflow
GitLab MR Code Review. Uses httpRequest, slack. Scheduled trigger; 18 nodes.
Source: https://github.com/junyeong-ai/claudio/blob/5899280b27ce362463a092893adca6f22728dc55/n8n-workflows/gitlab-mr-review.json — original creator credit. Request a take-down →
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