{
    "separateMajorMinor": true,
    "separateMultipleMajor": true,
    "regexManagers": [
        {
        "datasource": "docker",
        "depNameTemplate": "ubuntu",
        "fileMatch": ["^.*/?Dockerfile$"],
        "regexPattern": "^FROM ubuntu:(?<majorVersion>[a-zA-Z]+)-(?<build>\\d+)",
        "versioning": "simple"
        }
    ],
    "packageRules": [
        {
        "datasources": ["docker"],
        "depNameList": ["ubuntu"],
        "allowedVersions": "/^{{majorVersion}}-/",
        "versioning": "simple"
        }
    ]
}