1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
#!/usr/bin/env python3
"""Inspect the GitHub PR (including stack metadata) before continuation.
The setup job calls the GitHub REST API and writes continuation parameters.
Decision (matches GitHub's stacked-PR CI guidance):
- Not a PR / default branch / unstacked PR -> run expensive CI
- Stacked + lowest unmerged (targets the stack base, e.g. main) -> run expensive
- Stacked + top of stack (full stacked diff) -> run expensive
- Stacked + mid-stack (typical cascade rebase of remaining PRs) -> skip expensive
Always continue with run_required_check=true so a cheap GitHub status is posted.
API failures fail open (run expensive) so a lookup error never silently skips CI.
"""
from __future__ import annotations
import json
import os
import sys
import urllib.error
import urllib.parse
import urllib.request
GITHUB_API = "https://api.github.com"
PARAMS_PATH = os.environ.get("STACK_PARAMS_PATH", "pipeline-parameters.json")
def log(message: str) -> None:
print(message, flush=True)
def github_headers() -> dict[str, str]:
# GITHUB_TOKEN comes from a project context; omit Authorization on public repos.
headers = {
"Accept": "application/vnd.github+json",
"X-GitHub-Api-Version": "2022-11-28",
"User-Agent": "circleci-stacked-pr-analyzer",
}
token = (
os.environ.get("GITHUB_TOKEN", "").strip()
or os.environ.get("github_token", "").strip()
)
if token:
headers["Authorization"] = f"Bearer {token}"
return headers
def github_get(url: str) -> dict | list:
request = urllib.request.Request(url, headers=github_headers())
try:
with urllib.request.urlopen(request, timeout=30) as response:
return json.load(response)
except urllib.error.HTTPError as exc:
body = exc.read().decode("utf-8", errors="replace")
raise RuntimeError(f"GitHub API {exc.code} for {url}: {body[:500]}") from exc
def write_params(params: dict) -> None:
with open(PARAMS_PATH, "w", encoding="utf-8") as handle:
json.dump(params, handle)
log(f"Wrote {PARAMS_PATH}: {json.dumps(params)}")
def sanitize(value: str) -> str:
return " ".join(value.replace('"', "'").split())[:180]
def result(
*,
run_expensive: bool,
reason: str,
pr_number: str = "",
pr_url: str = "",
stack_position: str = "",
stack_size: str = "",
) -> dict:
return {
"run_expensive": run_expensive,
"run_required_check": True,
"pr_number": pr_number,
"pr_url": pr_url,
"stack_position": stack_position,
"stack_size": stack_size,
"decision_reason": sanitize(reason),
}
def pr_number_from_url(url: str) -> str:
return url.rstrip("/").rsplit("/", 1)[-1]
def find_pr(owner: str, repo: str, branch: str) -> dict | None:
# Prefer listing by head branch; fall back to CIRCLE_PULL_REQUEST(S).
head = urllib.parse.quote(f"{owner}:{branch}")
listed = github_get(
f"{GITHUB_API}/repos/{owner}/{repo}/pulls?head={head}&state=open&per_page=10"
)
if isinstance(listed, list) and listed:
if len(listed) > 1:
log(f"Multiple open PRs for {owner}:{branch}; using #{listed[0]['number']}")
return listed[0]
pull_url = os.environ.get("CIRCLE_PULL_REQUEST", "").strip()
if not pull_url:
pulls = os.environ.get("CIRCLE_PULL_REQUESTS", "").strip()
if pulls:
pull_url = pulls.split(",")[0].strip()
if not pull_url:
return None
number = pr_number_from_url(pull_url)
return github_get(f"{GITHUB_API}/repos/{owner}/{repo}/pulls/{number}")
def decide_from_pr(pr: dict) -> dict:
# Unstacked, lowest-unmerged, or top of stack -> expensive CI; mid-stack -> skip.
number = str(pr.get("number", ""))
html_url = pr.get("html_url", "")
base_ref = (pr.get("base") or {}).get("ref", "")
stack = pr.get("stack")
if not stack:
return result(
run_expensive=True,
reason="unstacked PR; run expensive CI",
pr_number=number,
pr_url=html_url,
)
position = stack.get("position")
size = stack.get("size")
stack_base = (stack.get("base") or {}).get("ref", "")
lowest_unmerged = bool(stack_base) and stack_base == base_ref
top = position is not None and size is not None and position == size
run_expensive = lowest_unmerged or top
if lowest_unmerged and top:
reason = "stacked PR; single remaining layer (lowest unmerged and top)"
elif lowest_unmerged:
reason = "stacked PR; lowest unmerged (targets stack base)"
elif top:
reason = "stacked PR; top of stack (full stacked diff)"
else:
reason = "stacked PR; mid-stack (typical cascade rebase); skip expensive CI"
return result(
run_expensive=run_expensive,
reason=reason,
pr_number=number,
pr_url=html_url,
stack_position="" if position is None else str(position),
stack_size="" if size is None else str(size),
)
def main() -> int:
owner = os.environ.get("CIRCLE_PROJECT_USERNAME", "")
repo = os.environ.get("CIRCLE_PROJECT_REPONAME", "")
branch = os.environ.get("CIRCLE_BRANCH", "")
log(f"Analyzing branch={branch} repo={owner}/{repo}")
if not owner or not repo:
# Fail open: never skip CI because project env vars were missing.
write_params(
result(run_expensive=True, reason="missing CIRCLE_PROJECT_* ; fail open")
)
return 0
try:
pr = find_pr(owner, repo, branch)
except Exception as exc: # noqa: BLE001 — fail open on any lookup error
log(f"PR lookup failed ({exc}); failing open")
write_params(
result(run_expensive=True, reason=f"GitHub API lookup failed; fail open: {exc}")
)
return 0
if not pr:
write_params(
result(
run_expensive=True,
reason="no open PR for this branch (default branch or non-PR push)",
)
)
return 0
number = pr.get("number")
if number:
try:
pr = github_get(f"{GITHUB_API}/repos/{owner}/{repo}/pulls/{number}")
except Exception as exc: # noqa: BLE001
log(f"Full PR fetch failed ({exc}); using list payload")
params = decide_from_pr(pr)
log(params["decision_reason"])
write_params(params)
return 0
if __name__ == "__main__":
sys.exit(main())
|
