refactor: reduce gh-wrappers' dependencies towards pipeline-template

Remove convenience-functions for implicitly creating github-APIs from
GitHubCfg-elements. Remove codepaths in github.util that accept those,
and instead require passing of github-api-instances. Adjust existing
codebase accordingly.

Also, purge model/tekton*, which has been unused for quite a while.

cli/gardener_ci/githubutil.py

@@ -41,7 +41,7 @@ def list_draft_releases(
     github_helper = GitHubRepositoryHelper(
         owner=github_repository_owner,
         name=github_repository_name,
-        github_cfg=github_cfg,
+        github_api=ccc.github.github_api(github_cfg),
     )
     if only_outdated:
         releases = [release for release in github_helper.repository.releases()]
@@ -74,7 +74,7 @@ def delete_releases(
     github_helper = GitHubRepositoryHelper(
         owner=github_repository_owner,
         name=github_repository_name,
-        github_cfg=github_cfg,
+        github_api=ccc.github.github_api(github_cfg),
     )
     github_helper.delete_releases(release_names=release_name)
 

concourse/steps/draft_release.mako

@@ -34,7 +34,6 @@ import release_notes.markdown
 from gitutil import GitHelper
 from github.util import (
     GitHubRepositoryHelper,
-    GitHubRepoBranch,
 )
 
 logger = logging.getLogger('draft-release')
@@ -89,15 +88,11 @@ ocm_version_lookup = cnudie.retrieve.version_lookup(
     ocm_repository_lookup=ocm_repository_lookup,
 )
 
-githubrepobranch = GitHubRepoBranch(
-    github_config=github_cfg,
-    repo_owner='${repo.repo_owner()}',
-    repo_name='${repo.repo_name()}',
-    branch='${repo.branch()}',
-)
-
-github_helper = GitHubRepositoryHelper.from_githubrepobranch(
-    githubrepobranch=githubrepobranch,
+github_helper = github.util.GitHubRepositoryHelper(
+    owner='${repo.repo_owner()}',
+    name='${repo.repo_name()}',
+    github_api=ccc.github.github_api(github_cfg),
+    default_branch='${repo.branch()}',
 )
 try:
     release_note_blocks = release_notes.fetch.fetch_draft_release_notes(

concourse/steps/release.mako

@@ -136,11 +136,14 @@ github_cfg = ccc.github.github_cfg_for_repo_url(
     '${repo.repo_path()}',
   )
 )
+github_api = ccc.github.github_api(github_cfg)
+repo_owner = '${repo.repo_owner()}'
+repo_name = '${repo.repo_name()}'
 
 githubrepobranch = github.util.GitHubRepoBranch(
     github_config=github_cfg,
-    repo_owner='${repo.repo_owner()}',
-    repo_name='${repo.repo_name()}',
+    repo_owner=repo_owner,
+    repo_name=repo_name,
     branch=repository_branch,
 )
 
@@ -366,8 +369,13 @@ git_helper = gitutil.GitHelper.from_githubrepobranch(
   githubrepobranch=githubrepobranch,
   repo_path=repo_dir,
 )
-github_helper = github.util.GitHubRepositoryHelper.from_githubrepobranch(githubrepobranch)
 branch = githubrepobranch.branch()
+github_helper = github.util.GitHubRepositoryHelper(
+  owner=repo_owner,
+  name=repo_name,
+  github_api=github_api,
+  default_branch=branch,
+)
 
 % if release_trait.rebase_before_release():
 logger.info(f'will fetch and rebase refs/heads/{branch}')

concourse/steps/update_component_deps.mako

@@ -41,6 +41,7 @@ import sys
 
 import dacite
 
+import ccc.github
 import ci.util
 import cnudie.util
 import cnudie.retrieve
@@ -95,7 +96,7 @@ pull_request_util = github.util.PullRequestUtil(
     owner=REPO_OWNER,
     name=REPO_NAME,
     default_branch=REPO_BRANCH,
-    github_cfg=github_cfg,
+    github_api=ccc.github.github_api(github_cfg),
 )
 
 ## hack / workaround: rebase to workaround concourse sometimes not refreshing git-resource

github/util.py

@@ -75,28 +75,20 @@ def __init__(
         self,
         owner: str,
         name: str,
-        default_branch: str='master',
-        github_cfg: GithubConfig=None,
         github_api: GitHub=None,
+        default_branch: str='master',
     ):
         '''
         Args:
             owner (str):    repository owner (also called organisation in GitHub)
             name (str):     repository name
             default_branch (str): branch to use for operations when not specified
-            github_cfg (GithubConfig): cfg to construct github api object from
             github_api (GitHub): github api to use
-
-        Exactly one of `github_cfg` and `github_api` must be passed as argument.
-        Passing a GitHub object is more flexible (but less convenient).
         '''
-        if not (bool(github_cfg) ^ bool(github_api)):
-            raise ValueError('exactly one of github_api and github_cfg must be given')
+        if not github_api:
+            raise ValueError('must pass github_api')
 
-        if github_cfg:
-            self.github = ccc.github.github_api(github_cfg)
-        else:
-            self.github = github_api
+        self.github = github_api
 
         self.repository = self._create_repository(
             owner=owner,
@@ -441,17 +433,6 @@ def create_or_update_file(
             )
         return response['commit'].sha
 
-    @staticmethod
-    def from_githubrepobranch(
-        githubrepobranch: GitHubRepoBranch,
-    ):
-        return GitHubRepositoryHelper(
-            github_cfg=githubrepobranch.github_config(),
-            owner=githubrepobranch.repo_owner(),
-            name=githubrepobranch.repo_name(),
-            default_branch=githubrepobranch.branch(),
-        )
-
     def retrieve_file_contents(self, file_path: str, branch: str=None):
         if branch is None:
             branch = self.default_branch

whd/pull_request.py

@@ -191,13 +191,14 @@ def github_api_for_pr_event(
         repo_url=ci.util.urljoin(github_host, repository_path),
         cfg_factory=cfg_set,
     )
+    github_api = ccc.github.github_api(github_cfg)
     owner, name = repository_path.split('/')
 
     try:
         github_helper = GitHubRepositoryHelper(
             owner=owner,
             name=name,
-            github_cfg=github_cfg,
+            github_api=github_api,
         )
     except NotFoundError:
         logger.warning(