Add trymerge (#388)

Tested locally using --dry-run

Apparently there is precedent for just copying the files over (see executorch PR huy linked below), so this copies over trymerge + dependencies

Removes check for release notes labels and sev

Can merge both ghstack and normal PRs. Be warned though, PRs merged this way will show up as "closed" instead of "merged" on the github UI

Future work: move trymerge + dependencies to test-infra (or download from pytorch), make sure its repo agnostic

Depends on pytorch/test-infra#5312

.github/merge_rules.yaml

@@ -0,0 +1,7 @@
+- name: superuser
+  patterns:
+  - '*'
+  approved_by:
+  - pytorch/metamates
+  mandatory_checks_name:
+  - Facebook CLA Check

.github/pytorch-probot.yml

@@ -0,0 +1 @@
+mergebot: True

.github/scripts/github_utils.py

@@ -0,0 +1,213 @@
+"""GitHub Utilities"""
+
+import json
+import os
+import warnings
+
+from dataclasses import dataclass
+from typing import Any, Callable, cast, Dict, List, Optional, Tuple, Union
+from urllib.error import HTTPError
+from urllib.parse import quote
+from urllib.request import Request, urlopen
+
+
+GITHUB_API_URL = "https://api.github.com"
+
+
+@dataclass
+class GitHubComment:
+    body_text: str
+    created_at: str
+    author_login: str
+    author_association: str
+    editor_login: Optional[str]
+    database_id: int
+    url: str
+
+
+def gh_fetch_url_and_headers(
+    url: str,
+    *,
+    headers: Optional[Dict[str, str]] = None,
+    data: Union[Optional[Dict[str, Any]], str] = None,
+    method: Optional[str] = None,
+    reader: Callable[[Any], Any] = lambda x: x.read(),
+) -> Tuple[Any, Any]:
+    if headers is None:
+        headers = {}
+    token = os.environ.get("GITHUB_TOKEN")
+    if token is not None and url.startswith(f"{GITHUB_API_URL}/"):
+        headers["Authorization"] = f"token {token}"
+
+    data_ = None
+    if data is not None:
+        data_ = data.encode() if isinstance(data, str) else json.dumps(data).encode()
+
+    try:
+        with urlopen(Request(url, headers=headers, data=data_, method=method)) as conn:
+            return conn.headers, reader(conn)
+    except HTTPError as err:
+        if err.code == 403 and all(
+            key in err.headers for key in ["X-RateLimit-Limit", "X-RateLimit-Used"]
+        ):
+            print(
+                f"""Rate limit exceeded:
+                Used: {err.headers['X-RateLimit-Used']}
+                Limit: {err.headers['X-RateLimit-Limit']}
+                Remaining: {err.headers['X-RateLimit-Remaining']}
+                Resets at: {err.headers['x-RateLimit-Reset']}"""
+            )
+        raise
+
+
+def gh_fetch_url(
+    url: str,
+    *,
+    headers: Optional[Dict[str, str]] = None,
+    data: Union[Optional[Dict[str, Any]], str] = None,
+    method: Optional[str] = None,
+    reader: Callable[[Any], Any] = lambda x: x.read(),
+) -> Any:
+    return gh_fetch_url_and_headers(
+        url, headers=headers, data=data, reader=json.load, method=method
+    )[1]
+
+
+def gh_fetch_json(
+    url: str,
+    params: Optional[Dict[str, Any]] = None,
+    data: Optional[Dict[str, Any]] = None,
+    method: Optional[str] = None,
+) -> List[Dict[str, Any]]:
+    headers = {"Accept": "application/vnd.github.v3+json"}
+    if params is not None and len(params) > 0:
+        url += "?" + "&".join(
+            f"{name}={quote(str(val))}" for name, val in params.items()
+        )
+    return cast(
+        List[Dict[str, Any]],
+        gh_fetch_url(url, headers=headers, data=data, reader=json.load, method=method),
+    )
+
+
+def _gh_fetch_json_any(
+    url: str,
+    params: Optional[Dict[str, Any]] = None,
+    data: Optional[Dict[str, Any]] = None,
+) -> Any:
+    headers = {"Accept": "application/vnd.github.v3+json"}
+    if params is not None and len(params) > 0:
+        url += "?" + "&".join(
+            f"{name}={quote(str(val))}" for name, val in params.items()
+        )
+    return gh_fetch_url(url, headers=headers, data=data, reader=json.load)
+
+
+def gh_fetch_json_list(
+    url: str,
+    params: Optional[Dict[str, Any]] = None,
+    data: Optional[Dict[str, Any]] = None,
+) -> List[Dict[str, Any]]:
+    return cast(List[Dict[str, Any]], _gh_fetch_json_any(url, params, data))
+
+
+def gh_fetch_json_dict(
+    url: str,
+    params: Optional[Dict[str, Any]] = None,
+    data: Optional[Dict[str, Any]] = None,
+) -> Dict[str, Any]:
+    return cast(Dict[str, Any], _gh_fetch_json_any(url, params, data))
+
+
+def gh_graphql(query: str, **kwargs: Any) -> Dict[str, Any]:
+    rc = gh_fetch_url(
+        "https://api.github.com/graphql",
+        data={"query": query, "variables": kwargs},
+        reader=json.load,
+    )
+    if "errors" in rc:
+        raise RuntimeError(
+            f"GraphQL query {query}, args {kwargs} failed: {rc['errors']}"
+        )
+    return cast(Dict[str, Any], rc)
+
+
+def _gh_post_comment(
+    url: str, comment: str, dry_run: bool = False
+) -> List[Dict[str, Any]]:
+    if dry_run:
+        print(comment)
+        return []
+    return gh_fetch_json_list(url, data={"body": comment})
+
+
+def gh_post_pr_comment(
+    org: str, repo: str, pr_num: int, comment: str, dry_run: bool = False
+) -> List[Dict[str, Any]]:
+    return _gh_post_comment(
+        f"{GITHUB_API_URL}/repos/{org}/{repo}/issues/{pr_num}/comments",
+        comment,
+        dry_run,
+    )
+
+
+def gh_post_commit_comment(
+    org: str, repo: str, sha: str, comment: str, dry_run: bool = False
+) -> List[Dict[str, Any]]:
+    return _gh_post_comment(
+        f"{GITHUB_API_URL}/repos/{org}/{repo}/commits/{sha}/comments",
+        comment,
+        dry_run,
+    )
+
+
+def gh_delete_comment(org: str, repo: str, comment_id: int) -> None:
+    url = f"{GITHUB_API_URL}/repos/{org}/{repo}/issues/comments/{comment_id}"
+    gh_fetch_url(url, method="DELETE")
+
+
+def gh_fetch_merge_base(org: str, repo: str, base: str, head: str) -> str:
+    merge_base = ""
+    # Get the merge base using the GitHub REST API. This is the same as using
+    # git merge-base without the need to have git. The API doc can be found at
+    # https://docs.github.com/en/rest/commits/commits?apiVersion=2022-11-28#compare-two-commits
+    try:
+        json_data = gh_fetch_url(
+            f"{GITHUB_API_URL}/repos/{org}/{repo}/compare/{base}...{head}",
+            headers={"Accept": "application/vnd.github.v3+json"},
+            reader=json.load,
+        )
+        if json_data:
+            merge_base = json_data.get("merge_base_commit", {}).get("sha", "")
+        else:
+            warnings.warn(
+                f"Failed to get merge base for {base}...{head}: Empty response"
+            )
+    except Exception as error:
+        warnings.warn(f"Failed to get merge base for {base}...{head}: {error}")
+
+    return merge_base
+
+
+def gh_update_pr_state(org: str, repo: str, pr_num: int, state: str = "open") -> None:
+    url = f"{GITHUB_API_URL}/repos/{org}/{repo}/pulls/{pr_num}"
+    try:
+        gh_fetch_url(url, method="PATCH", data={"state": state})
+    except HTTPError as err:
+        # When trying to open the pull request, error 422 means that the branch
+        # has been deleted and the API couldn't re-open it
+        if err.code == 422 and state == "open":
+            warnings.warn(
+                f"Failed to open {pr_num} because its head branch has been deleted: {err}"
+            )
+        else:
+            raise
+
+
+def gh_query_issues_by_labels(
+    org: str, repo: str, labels: List[str], state: str = "open"
+) -> List[Dict[str, Any]]:
+    url = f"{GITHUB_API_URL}/repos/{org}/{repo}/issues"
+    return gh_fetch_json(
+        url, method="GET", params={"labels": ",".join(labels), "state": state}
+    )