Auto merge of #124631 - Kobzol:arbitrary-try-build, r=<try>

CI: enable arbitrary try build

This PR should enable running arbitrary try builds with ``@bors` try`. So far there is no support for this in bors! You would need to manually add a special line (see below) containing to the PR description (this will later be automated with new bors).

ci-job: aarch64-gnu

r? `@ghost`

.github/workflows/ci.yml

@@ -52,6 +52,8 @@ jobs:
       - name: Checkout the source code
         uses: actions/checkout@v4
       - name: Calculate the CI job matrix
+        env:
+          COMMIT_MESSAGE: ${{ github.event.head_commit.message }}
         run: python3 src/ci/github-actions/calculate-job-matrix.py >> $GITHUB_OUTPUT
         id: jobs
   job:

src/ci/github-actions/calculate-job-matrix.py

@@ -8,10 +8,11 @@
 and filters them based on the event that happened on CI.
 """
 import dataclasses
-import enum
 import json
 import logging
 import os
+import re
+import typing
 from pathlib import Path
 from typing import List, Dict, Any, Optional
 
@@ -44,22 +45,51 @@ def add_base_env(jobs: List[Job], environment: Dict[str, str]) -> List[Job]:
     return jobs
 
 
-class WorkflowRunType(enum.Enum):
-    PR = enum.auto()
-    Try = enum.auto()
-    Auto = enum.auto()
+@dataclasses.dataclass
+class PRRunType:
+    pass
+
+
+@dataclasses.dataclass
+class TryRunType:
+    job: Optional[str] = None
+
+
+@dataclasses.dataclass
+class AutoRunType:
+    pass
+
+
+WorkflowRunType = typing.Union[PRRunType, TryRunType, AutoRunType]
 
 
 @dataclasses.dataclass
 class GitHubCtx:
     event_name: str
     ref: str
     repository: str
+    commit_message: Optional[str]
+
+
+def get_job_from_commit(ctx: GitHubCtx) -> Optional[str]:
+    """
+    Tries to parse a name of a CI job that should be executed in the form of
+    ci-job: <job-name>
+    from the commit message of the passed GitHub context.
+    """
+    if ctx.commit_message is None:
+        return None
+
+    regex = re.compile(r"ci-job: (.*)")
+    match = regex.search(ctx.commit_message)
+    if match is None:
+        return None
+    return match.group(1)
 
 
 def find_run_type(ctx: GitHubCtx) -> Optional[WorkflowRunType]:
     if ctx.event_name == "pull_request":
-        return WorkflowRunType.PR
+        return PRRunType()
     elif ctx.event_name == "push":
         old_bors_try_build = (
             ctx.ref in ("refs/heads/try", "refs/heads/try-perf") and
@@ -72,20 +102,29 @@ def find_run_type(ctx: GitHubCtx) -> Optional[WorkflowRunType]:
         try_build = old_bors_try_build or new_bors_try_build
 
         if try_build:
-            return WorkflowRunType.Try
+            job_name = get_job_from_commit(ctx)
+            return TryRunType(job=job_name)
 
         if ctx.ref == "refs/heads/auto" and ctx.repository == "rust-lang-ci/rust":
-            return WorkflowRunType.Auto
+            return AutoRunType()
 
     return None
 
 
 def calculate_jobs(run_type: WorkflowRunType, job_data: Dict[str, Any]) -> List[Job]:
-    if run_type == WorkflowRunType.PR:
+    if isinstance(run_type, PRRunType):
         return add_base_env(name_jobs(job_data["pr"], "PR"), job_data["envs"]["pr"])
-    elif run_type == WorkflowRunType.Try:
-        return add_base_env(name_jobs(job_data["try"], "try"), job_data["envs"]["try"])
-    elif run_type == WorkflowRunType.Auto:
+    elif isinstance(run_type, TryRunType):
+        jobs = job_data["try"]
+        if run_type.job is not None:
+            jobs = [job for job in job_data["auto"] if job["image"] == run_type.job]
+            if not jobs:
+                raise Exception(
+                    f"CI job `{run_type.job}` asked for in the try build does not exist"
+                )
+
+        return add_base_env(name_jobs(jobs, "try"), job_data["envs"]["try"])
+    elif run_type is AutoRunType:
         return add_base_env(name_jobs(job_data["auto"], "auto"), job_data["envs"]["auto"])
 
     return []
@@ -99,19 +138,25 @@ def skip_jobs(jobs: List[Dict[str, Any]], channel: str) -> List[Job]:
 
 
 def get_github_ctx() -> GitHubCtx:
+    event_name = os.environ["GITHUB_EVENT_NAME"]
+
+    commit_message = None
+    if event_name == "push":
+        commit_message = os.environ["COMMIT_MESSAGE"]
     return GitHubCtx(
-        event_name=os.environ["GITHUB_EVENT_NAME"],
+        event_name=event_name,
         ref=os.environ["GITHUB_REF"],
-        repository=os.environ["GITHUB_REPOSITORY"]
+        repository=os.environ["GITHUB_REPOSITORY"],
+        commit_message=commit_message
     )
 
 
 def format_run_type(run_type: WorkflowRunType) -> str:
-    if run_type == WorkflowRunType.PR:
+    if isinstance(run_type, PRRunType):
         return "pr"
-    elif run_type == WorkflowRunType.Auto:
+    elif isinstance(run_type, AutoRunType):
         return "auto"
-    elif run_type == WorkflowRunType.Try:
+    elif isinstance(run_type, TryRunType):
         return "try"
     else:
         raise AssertionError()