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Update the outstanding backport PRs automatically, take 2
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We already do this, but it doesn't work -- turns out GitHub doesn't
start the workflows from merge commits pushed through the GitHub
Actions. Push instead using the personal access token. This way a user
can only push to their personal fork, so change this as well.
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@akuzm
akuzm committed Feb 19, 2025
1 parent eb2b197 commit 6010da4
Showing 1 changed file with 39 additions and 40 deletions.
79 changes: 39 additions & 40 deletions scripts/backport.py
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Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,6 @@ def get_referenced_issue(pr_number):
def set_auto_merge(pr_number):
"""Enable auto-merge for the given PR"""

owner, name = target_repo_name.split("/")
# We first have to find out the PR id, which is some base64 string, different
# from its number.
query = string.Template(
Expand All @@ -101,7 +100,9 @@ def set_auto_merge(pr_number):
}
}
}"""
).substitute(pr_number=pr_number, owner=owner, name=name)
).substitute(
pr_number=pr_number, owner=source_repo.owner.login, name=source_repo.name
)
result = run_query(query)
pr_id = result["data"]["repository"]["pullRequest"]["id"]

Expand Down Expand Up @@ -138,33 +139,16 @@ def git_returncode(command):
# The token has to have the "access public repositories" permission, or else creating a PR returns 404.
github = Github(os.environ.get("GITHUB_TOKEN"))

# If we are running inside Github Action, will modify the main repo.
source_remote = "origin"
source_repo_name = os.environ.get("GITHUB_REPOSITORY")
target_remote = source_remote
target_repo_name = source_repo_name

source_repo_name = os.environ.get("GITHUB_REPOSITORY") # This is set in GitHub Actions.
if not source_repo_name:
# We are running manually for debugging, probably want to modify a fork.
source_repo_name = "timescale/timescaledb"
target_repo_name = os.environ.get("BACKPORT_TARGET_REPO")
target_remote = os.environ.get("BACKPORT_TARGET_REMOTE")
if not target_repo_name or not target_remote:
print(
"Please specify the target repositories for debugging, using the "
"environment variables BACKPORT_TARGET_REPO (e.g. `timescale/timescaledb`) "
"and BACKPORT_TARGET_REMOTE (e.g. `origin`).",
file=sys.stderr,
)
sys.exit(1)

print(
f"Will look at '{source_repo_name}' (git remote '{source_remote}') for bug fixes, "
f"and create the backport PRs in '{target_repo_name}' (git remote '{target_remote}')."
f"Will look at '{source_repo_name}' (git remote '{source_remote}') for bug fixes."
)

source_repo = github.get_repo(source_repo_name)
target_repo = github.get_repo(target_repo_name)

# Fetch the main branch. Apparently the local repo can be shallow in some cases
# in Github Actions, so specify the depth. --unshallow will complain on normal
Expand Down Expand Up @@ -197,21 +181,16 @@ def git_returncode(command):
# in Github Actions, so specify the depth. --unshallow will complain on normal
# repositories, this is why we don't use it here.
git_check(
f"fetch --quiet --depth={HISTORY_DEPTH} {target_remote} {backport_target}:refs/remotes/{target_remote}/{backport_target}"
f"fetch --quiet --depth={HISTORY_DEPTH} {source_remote} {backport_target}:refs/remotes/{source_remote}/{backport_target}"
)

# Also fetch all branches from the target repository, because we use the presence
# of the backport branches to determine that a backport exists. It's not convenient
# to query for branch existence through the PyGithub API.
git_check(f"fetch {target_remote}")

# Find out which commits are unique to main and target branch. Also build sets of
# the titles of these commits. We will compare the titles to check whether a
# commit was backported.
main_commits = [
line.split("\t")
for line in git_output(
f'log -{HISTORY_DEPTH} --pretty="format:%h\t%s" {target_remote}/{backport_target}..{source_remote}/main'
f'log -{HISTORY_DEPTH} --pretty="format:%h\t%s" {source_remote}/{backport_target}..{source_remote}/main'
).splitlines()
if line
]
Expand All @@ -221,7 +200,7 @@ def git_returncode(command):
branch_commits = [
line.split("\t")
for line in git_output(
f'log -{HISTORY_DEPTH} --pretty="format:%h\t%s" {source_remote}/main..{target_remote}/{backport_target}'
f'log -{HISTORY_DEPTH} --pretty="format:%h\t%s" {source_remote}/main..{source_remote}/{backport_target}'
).splitlines()
if line
]
Expand Down Expand Up @@ -355,24 +334,27 @@ def should_backport_by_labels(number, title, labels):
def branch_has_open_pr(repo, branch):
"""Check whether the given branch has an open PR."""

# There's no way to search by branch name + fork name, but in the case the
# branch name is probably unique. We'll bail out if we find more than one PR.
template = """query {
repository(name: "$repo_name", owner: "$repo_owner") {
ref(qualifiedName: "$branch") {
associatedPullRequests(first: 1) {
nodes { closed }}}}}"""
pullRequests(headRefName: "$branch", first: 2) {
nodes { closed }}}}"""

params = {
"branch": branch,
"repo_name": repo.name,
"repo_owner": repo.owner.login,
}

result = run_query(string.Template(template).substitute(params))
query = string.Template(template).substitute(params)

result = run_query(query)

# This returns:
# {'data': {'repository': {'ref': {'associatedPullRequests': {'nodes': [{'closed': True}]}}}}}
# {'data': {'repository': {'pullRequests': {'nodes': [{'closed': True}]}}}}

prs = result["data"]["repository"]["ref"]["associatedPullRequests"]["nodes"]
prs = result["data"]["repository"]["pullRequests"]["nodes"]

if not prs or len(prs) != 1 or not prs[0]:
return None
Expand Down Expand Up @@ -424,6 +406,20 @@ def report_backport_not_done(original_pr, reason, details=None):
f"Will commit as {os.environ['GIT_COMMITTER_NAME']} <{os.environ['GIT_COMMITTER_EMAIL']}>"
)

# We have to push using the personal access token of the automation user.
# If we use the default credentials of the GitHub Actions to push, the workflows
# in the backport PRs don't start. To keep the things more fun for us, GitHub
# does this only for the merge commits, but not for the new PRs.
target_remote = "backport-target-remote"
git_returncode(f"remote remove {target_remote}")
git_check(
f'remote add {target_remote} https://{os.environ["GITHUB_TOKEN"]}@github.com/{token_user.login}/{source_repo.name}.git'
)

# Fetch all branches from the target repository, because we use the presence
# of the backport branches to determine that a backport exists. It's not convenient
# to query for branch existence through the PyGithub API.
git_check(f"fetch {target_remote}")

# Now, go over the list of PRs that we have collected, and try to backport
# each of them.
Expand All @@ -440,6 +436,8 @@ def report_backport_not_done(original_pr, reason, details=None):

original_pr = pr_info.pygithub_pr
backport_branch = f"backport/{backport_target}/{original_pr.number}"
# We're creating the backport PR from the token user's fork.
backport_pr_head = f"{token_user.login}:{backport_branch}"

# If there is already a backport branch for this PR, this probably means
# that we already created the backport PR. Update it, because the PR might
Expand All @@ -454,7 +452,7 @@ def report_backport_not_done(original_pr, reason, details=None):
f'Backport branch {backport_branch} for PR #{original_pr.number}: "{original_pr.title}" already exists.'
)

if not branch_has_open_pr(target_repo, backport_branch):
if not branch_has_open_pr(source_repo, backport_branch):
# The PR can be closed manually when the backport is not needed, or
# can not exist when there was some error. We are only interested in
# the most certain case when there is an open backport PR.
Expand All @@ -468,15 +466,15 @@ def report_backport_not_done(original_pr, reason, details=None):
)
# Use merge and no force-push, so that the simultaneous changes made by
# other users are not accidentally overwritten.
git_check(f"merge --quiet {target_remote}/{backport_target}")
git_check(f"merge --quiet --no-edit {source_remote}/{backport_target}")
git_check(f"push --quiet {target_remote} @:{backport_branch}")
continue

# Try to cherry-pick the commits.
git_check("reset --hard")
git_check("clean -xfd")
git_check(
f"checkout --quiet --force --detach {target_remote}/{backport_target} > /dev/null"
f"checkout --quiet --force --detach {source_remote}/{backport_target} > /dev/null"
)

commit_shas = [commit.sha for commit in pr_info.pygithub_commits]
Expand Down Expand Up @@ -570,10 +568,11 @@ def report_backport_not_done(original_pr, reason, details=None):
)

# Create the backport PR.
backport_pr = target_repo.create_pull(
backport_pr = source_repo.create_pull(
title=f"Backport to {backport_target}: #{original_pr.number}: {original_pr.title}",
body=backport_description,
head=backport_branch,
# We're creating PR from the token user's fork.
head=backport_pr_head,
base=backport_target,
)
backport_pr.add_to_labels("is-auto-backport")
Expand Down

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