wip: Include manifest diff in PR description

For e.g. testing when running with `--dry-run`, the token may not be
necessary.

updatebot.py

@@ -5,6 +5,7 @@ import logging
 import functools
 import os
 import re
+import subprocess
 import tempfile
 import threading
 import tomllib
@@ -122,6 +123,10 @@ class BaseProject(abc.ABC, pydantic.BaseModel):
     def apply_update(self, path: Path, version: str) -> None:
         raise NotImplementedError
 
+    @abc.abstractmethod
+    def diff(self, path: Path) -> str:
+        raise NotImplementedError
+
 
 class KustomizeProject(BaseProject):
     kind: Literal['kustomize']
@@ -153,6 +158,26 @@ class KustomizeProject(BaseProject):
         with filepath.open('wb') as f:
             yaml.dump(kustomization, f)
 
+    def diff(self, path: Path) -> str:
+        try:
+            p = subprocess.run(
+                ['kubectl', 'diff', '-k', '.'], 
+                cwd=path,
+                check=False,
+                capture_output=True,
+                stdin=subprocess.DEVNULL,
+                encoding='utf-8',
+            )
+        except FileNotFoundError as e:
+            log.warning('Cannot compute manifest diff: %s', e)
+            return ''
+        if not p.stdout and p.returncode != 0:
+            log.error('Error computing manifest diff: %s', p.stderr)
+            return ''
+        else:
+            assert p.stdout is not None
+            return p.stdout
+
 
 class DirectoryProject(BaseProject):
     kind: Literal['dir'] | Literal['directory']
@@ -166,7 +191,7 @@ Project = Union[
 
 class RepoConfig(pydantic.BaseModel):
     url: str
-    token_file: Path
+    token_file: Optional[Path] = None
     branch: str = 'master'
 
     @functools.cached_property
@@ -176,16 +201,18 @@ class RepoConfig(pydantic.BaseModel):
         return urllib.parse.urlunsplit(urlparts)
 
     @functools.cached_property
-    def auth_token(self) -> str:
+    def auth_token(self) -> Optional[str]:
-        return self.token_file.read_text().strip()
+        if self.token_file:
+            return self.token_file.read_text().strip()
 
     def get_git_url(self) -> str:
         session = _get_session()
+        headers = {}
+        if token := self.auth_token:
+            headers['Authorization'] = f'Bearer {token}'
         r = session.get(
             self.repo_api_url,
-            headers={
+            headers=headers,
-                'Authorization': f'token {self.auth_token}',
-            },
         )
         data = r.json()
         if ssh_url := data.get('ssh_url'):
@@ -193,7 +220,11 @@ class RepoConfig(pydantic.BaseModel):
         return data['clone_url']
 
     def create_pr(
-        self, title: str, source_branch: str, target_branch: str
+        self,
+        title: str,
+        source_branch: str,
+        target_branch: str,
+        body: Optional[str] = None,
     ) -> None:
         session = _get_session()
         r = session.post(
@@ -205,6 +236,7 @@ class RepoConfig(pydantic.BaseModel):
                 'title': title,
                 'base': target_branch,
                 'head': source_branch,
+                'body': body,
             },
         )
         log.log(TRACE, '%r', r.content)
@@ -235,7 +267,7 @@ class Arguments:
 
 def update_project(
     repo: git.Repo, name: str, project: Project
-) -> Optional[git.Commit]:
+) -> tuple[Optional[git.Commit], Optional[str]]:
     basedir = Path(repo.working_dir)
     log.debug('Checking for latest version of %s', name)
     latest = project.source.get_latest_version()
@@ -248,10 +280,12 @@ def update_project(
         repo.index.add(str(path))
         c = repo.index.commit(f'{name}: Update to {latest}')
         log.info('Commited %s %s', str(c)[:7], c.summary)
-        return c
+        log.debug('Computing manifest diff')
+        diff = project.diff(path)
+        return (c, diff)
     else:
         log.info('No changes to commit')
-        return None
+        return (None, None)
 
 
 def parse_args() -> Arguments:
@@ -322,8 +356,11 @@ def main() -> None:
         log.debug('Checking out new branch: %s', args.branch_name)
         repo.heads[0].checkout(force=True, B=args.branch_name)
         title = None
+        pr_desc = ''
         for project in projects:
-            commit = update_project(repo, project, config.projects[project])
+            commit, diff = update_project(
+                repo, project, config.projects[project]
+            )
             if commit and not title:
                 if not isinstance(commit.summary, str):
                     title = bytes(commit.summary).decode(
@@ -331,17 +368,29 @@ def main() -> None:
                     )
                 else:
                     title = commit.summary
+            if diff:
+                pr_desc += diff
         if not title:
             log.info('No changes made')
             return
-        repo.head.reference.set_tracking_branch(
-            git.RemoteReference(
-                repo, f'refs/remotes/origin/{args.branch_name}'
-            )
-        )
         if not args.dry_run:
+            repo.head.reference.set_tracking_branch(
+                git.RemoteReference(
+                    repo, f'refs/remotes/origin/{args.branch_name}'
+                )
+            )
             repo.remote().push(force=True)
-            config.repo.create_pr(title, args.branch_name, config.repo.branch)
+            if pr_desc:
+                pr_desc = (
+                    '<details>\n<summary>Manifest diff</summary>\n\n'
+                    f'```diff\n{pr_desc}```\n'
+                    '</details>'
+                )
+            config.repo.create_pr(
+                title, args.branch_name, config.repo.branch, pr_desc
+            )
+        elif pr_desc:
+            print(pr_desc)
 
 
 if __name__ == '__main__':