aws-machine-image datasource: PR title exceeds maximum length - how to properly configure?

[ByteCrunch]

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Self-hosted Renovate

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GitLab

Please tell us more about your question or problem

I'm using the following renovate config to utilize the aws-machine-image datasource:

renovate.json in repo

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "extends": [
    "config:recommended",
    "local>renovate/bot"
  ],
  "baseBranches": [
    "master"
  ],
  "assignees": [
    "[...]"
  ],
  "packageRules": [
    {
      "matchDatasources": ["aws-machine-image"],
      "patch": { "enabled": true }
    }
  ],
  "customManagers": [
    {
      "customType": "regex",
      "fileMatch": [".*"],
      "matchStrings":
      [
        ".*amiFilter=(?<lookupName>.*?)\\n(.*currentImageName=(?<currentDigest>.*?)\\n)?(.*\\n)?.*?(?<depName>[a-zA-Z0-9-_:]*)[ ]*?[:|=][ ]*?[\"|']?(?<currentValue>ami-[a-z0-9]{17})[\"|']?.*"
      ],
      "datasourceTemplate": "aws-machine-image",
      "versioningTemplate": "aws-machine-image"
    }
  ],
  "dependencyDashboard": true,
  "labels": [
    "renovate"
  ]
}

This will result in really long branch-names, commit messages and PR title as the dependency name looks for example like "[{"Name":"owner-id","Values":["602401143452"]},{"Name":"name","Values":["amazon-eks-arm64-node-1.30-*"]},{"region": "eu-west-1"}]"

This results in actually failing to create the PR, because it exceeds the limit of 255 chars in GitLab.
There seems to be no official way to change the char limit for PR titles beside changing the model in the GitLab source code which is not feasible for me.

Also setting custom renovate commitMessage is not recommended and deprecated according to the documentation of renovate configuration options.
I also don't want to change the behavior for other data sources.

What is the correct way to use this datasource? Is there something wrong in my configuration?

Renovate Version is: 38.57.1
GitLab version is: 17.9.1-ee

Kind regards
Manuel

Logs (if relevant)

Logs

DEBUG: packageFiles with updates (repository=it-automation/gitops-inventories/eks/eks-renovate-test, baseBranch=master)
       "config": {
         "regex": [
           {
             "datasourceTemplate": "aws-machine-image",
             "deps": [
               {
                 "currentDigest": "amazon-eks-arm64-node-1.25-v20231027",
                 "currentValue": "ami-0071d65dae3b96781",
                 "currentVersion": "ami-0071d65dae3b96781",
                 "datasource": "aws-machine-image",
                 "depName": "[{\"Name\":\"owner-id\",\"Values\":[\"602401143452\"]},{\"Name\":\"name\",\"Values\":[\"amazon-eks-arm64-node-1.25-*\"]},{\"region\": \"eu-west-1\"}]",
                 "fixedVersion": "ami-0071d65dae3b96781",
                 "isSingleVersion": true,
                 "packageName": "[{\"Name\":\"owner-id\",\"Values\":[\"602401143452\"]},{\"Name\":\"name\",\"Values\":[\"amazon-eks-arm64-node-1.25-*\"]},{\"region\": \"eu-west-1\"}]",
                 "replaceString": "    # amiFilter=[{\"Name\":\"owner-id\",\"Values\":[\"602401143452\"]},{\"Name\":\"name\",\"Values\":[\"amazon-eks-arm64-node-1.25-*\"]},{\"region\": \"eu-west-1\"}]\n    # currentImageName=amazon-eks-arm64-node-1.25-v20231027\n    \"1.25\": \"ami-0071d65dae3b96781\"",
                 "versioning": "aws-machine-image",
                 "warnings": [],
                 "updates": [
                   {
                     "bucket": "non-major",
                     "newVersion": "ami-02db1720c55cea1ae",
                     "newValue": "ami-02db1720c55cea1ae",
                     "newDigest": "amazon-eks-arm64-node-1.25-v20250228",
                     "releaseTimestamp": "2025-02-28T23:32:18.000Z",
                     "newMajor": 1,
                     "newMinor": 0,
                     "newPatch": 0,
                     "updateType": "patch",
                     "branchName": "renovate/{\"name\"-\"owner-id\",\"values\"-\"602401143452\"-},{\"name\"-\"name\",\"values\"-\"amazon-eks-arm64-node-1.25-\"-},{\"region\"-\"eu-west-1\"}-replacement"
                   }
                 ]
               }
             ],
             "matchStrings": [
               ".*amiFilter=(?<packageName>.*?)\\n(.*currentImageName=(?<currentDigest>.*?)\\n)?(.*\\n)?.*?(?<depName>[a-zA-Z0-9-_:]*)[ ]*?[:|=][ ]*?[\"|']?(?<currentValue>ami-[a-z0-9]{17})[\"|']?.*"
             ],
             "packageFile": "README.md",
             "versioningTemplate": "aws-machine-image"
           },

[...]

DEBUG: Pull request creation error (repository=it-automation/gitops-inventories/eks/eks-renovate-test, baseBranch=master, branch=renovate/{"name"-"owner-id","values"-"602401143452"-},{"name"-"name","values"-"amazon-eks-arm64-node-1.25-"-},{"region"-"eu-west-1"}-replacement)
       "err": {
         "name": "HTTPError",
         "code": "ERR_NON_2XX_3XX_RESPONSE",
         "timings": {
           "start": 1741695899396,
           "socket": 1741695899396,
           "lookup": 1741695899396,
           "connect": 1741695899396,
           "secureConnect": 1741695899396,
           "upload": 1741695899397,
           "response": 1741695899597,
           "end": 1741695899598,
           "phases": {
             "wait": 0,
             "dns": 0,
             "tcp": 0,
             "tls": 0,
             "request": 1,
             "firstByte": 200,
             "download": 1,
             "total": 202
           }
         },
         "message": "Response code 400 (Bad Request)",
         "stack": "HTTPError: Response code 400 (Bad Request)\n    at Request.<anonymous> (/usr/local/renovate/node_modules/.pnpm/[email protected]/node_modules/got/dist/source/as-promise/index.js:118:42)\n    at processTicksAndRejections (node:internal/process/task_queues:95:5)",
         "options": {
           "headers": {
             "user-agent": "RenovateBot/38.57.1 (https://github.com/renovatebot/renovate)",
             "accept": "application/json",
             "authorization": "***********",
             "content-type": "application/json",
             "content-length": "1862",
             "accept-encoding": "gzip, deflate, br"
           },
           "url": "https://[]/merge_requests",
           "hostType": "gitlab",
           "username": "",
           "password": "",
           "method": "POST",
           "http2": false
         },
         "response": {
           "statusCode": 400,
           "statusMessage": "Bad Request",
           "body": {"message": {"title": ["is too long (maximum is 255 characters)"]}},
           "headers": {
            [...]
           },
           "httpVersion": "1.1",
           "retryCount": 0
         }
       }

[rarkins]

Try using overrideDepName in side a package rulle