trailing slashes in registryUrl group inside replaceString are stripped

[muja]

How are you running Renovate?

Self-hosted Renovate

If you're self-hosting Renovate, tell us which platform (GitHub, GitLab, etc) and which version of Renovate.

irrelevant, but: BitBucket Server, renovate version 39.182.5

Please tell us more about your question or problem

When using a custom datasource with a regex matcher like the following where the registryUrl is inside the replaceString:

{
  "customDatasources": {
    "html": {
      "format": "html"
    }
  },
  "customManagers": [
    {
      "customType": "regex",
      "fileMatch": [
        "^Containerfile$"
      ],
      "matchStrings": [
        "ARG [A-Z]+_VERSION=(?<currentValue>\\S+) # (?<depName>.*?) @ html(:(?<extractVersion>\\S+))? @ (?<registryUrl>https://\\S+)\n"
      ],
      "datasourceTemplate": "custom.html"
    },
  ]
}

and this line in the Containerfile:

ARG OPC_VERSION=1.17.0 # openshift/pipelines @ html:^(?<version>.*)/$ @ https://mirror.openshift.com/pub/openshift-v4/clients/pipelines/

the trailing slash will be deleted in the HTTP request. In this case, this is a problem because the website does not work without a trailing slash and in general, this should be classified as a bug since in HTTP protocol, the path is arbitrary, even though it is not conventional.

I was able to workaround it by adding a #, even though that is not very nice

Logs (if relevant)

Logs

TRACE: Compiling template (repository=foo/bar)
       "template": "custom.html",
       "filteredInput": {
         "allowedCommands": [],
         "allowedEnv": [],
         "allowCommandTemplating": true,
         "allowCustomCrateRegistries": false,
         "allowedHeaders": ["X-*"],
         "allowPlugins": false,
         "allowScripts": false,
         "binarySource": "install",
         "cacheDir": "/tmp/renovate/cache",
         "cacheHardTtlMinutes": 10080,
         "cacheTtlOverride": {},
         "containerbaseDir": "/tmp/renovate/cache/containerbase",
         "customEnvVariables": {},
         "dockerChildPrefix": "renovate_",
         "dockerCliOptions": null,
         "dockerSidecarImage": "ghcr.io/containerbase/sidecar:13.8.3",
         "dockerUser": null,
         "dryRun": null,
         "encryptedWarning": null,
         "exposeAllEnv": false,
         "executionTimeout": 15,
         "githubTokenWarn": true,
         "localDir": "/tmp/renovate/repos/bitbucket-server/foo/bar",
         "migratePresets": {},
         "presetCachePersistence": false,
         "privateKey": null,
         "privateKeyOld": null,
         "gitTimeout": 0,
         "platform": "bitbucket-server",
         "endpoint": "https://bitbucket.my.org/",
         "httpCacheTtlDays": 90,
         "autodiscoverRepoSort": null,
         "autodiscoverRepoOrder": null,
         "userAgent": null,
         "dockerMaxPages": 20,
         "s3Endpoint": null,
         "s3PathStyle": false,
         "cachePrivatePackages": false,
         "currentValue": "1.17.0",
         "depName": "openshift/pipelines",
         "extractVersion": "^(?<version>.*)/$",
         "registryUrl": "https://mirror.openshift.com/pub/openshift-v4/clients/pipelines/",

[...]

TRACE: packageFiles (repository=warp/warp)
       "config": {
         "regex": [
           {
             "deps": [
               {
                 "depName": "openshift/pipelines",
                 "currentValue": "1.17.0",
                 "datasource": "custom.html",
                 "extractVersion": "^(?<version>.*)/$",
                 "registryUrls": [
                   "https://mirror.openshift.com/pub/openshift-v4/clients/pipelines/"
                 ],
                 "replaceString": "ARG OPC_VERSION=1.17.0      # openshift/pipelines           @ html:^(?<version>.*)/$ @ https://mirror.openshift.com/pub/openshift-v4/clients/pipelines/\n"
               }
             ],
             "matchStrings": [
               "ARG [A-Z_]+_VERSION=(?<currentValue>\\S+)\\s+#\\s*(?<depName>.*?)\\s*@\\s*html(:(?<extractVersion>\\S+))?\\s*@\\s*(?<registryUrl>https://\\S+)\n"
             ],
             "datasourceTemplate": "custom.html",
             "packageFile": "Containerfile"
           }
         ]
       }

[ ... ]

TRACE: lookupUpdates (repository=foo/bar dependency=openshift/pipelines)
       "currentValue": "1.17.0"
TRACE: Compiling template (repository=foo/bar)
       "template": "https://mirror.openshift.com/pub/openshift-v4/clients/pipelines",

[viceice]

this is an issue with our join url parts util. maybe we should update it to preserve trailing slashes