[CI] Extend metrics container to log BuildKite metrics

The current container focuses on Github metrics. Before deprecating BuildKite,
we want to make sure the new infra quality is better, or at least the same.

Being able to compare buildkite metrics with github metrics on grafana will
allow us to easily present the comparison.

BuildKite API allows filtering, but doesn't allow changing the result
ordering. Meaning we are left with builds ordered by IDs.
This means a completed job can appear before a running job in the list.
2 solutions from there:
 - keep the cursor on the oldest running workflow
 - keep a list of running workflows to compare.

Because there is no guarantees in workflow ordering, waiting for the
oldest build to complete before reporting any newer build could mean
delaying the more recent build completion reporting by a few hours.
And because grafana cannot ingest metrics older than 2 hours, this is
not an option.

Thus we leave with the second solution: remember what jobs were running
during the last iteration, and record them as soon as they are
completed. Buildkite has at most ~100 pending jobs, so keeping all those
IDs should be OK.

Author: Keenuts

.ci/metrics/metrics.py

@@ -1,5 +1,6 @@
 import collections
 import datetime
+import dateutil
 import github
 import logging
 import os
@@ -53,6 +54,18 @@
 # by trial and error).
 GRAFANA_METRIC_MAX_AGE_MN = 120
 
+# Lists the BuildKite jobs we want to track. Maps the BuildKite job name to
+# the metric name in Grafana. This is important not to lose metrics history
+# if the workflow name changes.
+BUILDKITE_WORKFLOW_TO_TRACK = {
+    ":linux: Linux x64": "buildkite_linux",
+    ":windows: Windows x64": "buildkite_windows",
+}
+
+# Number of builds to fetch per page. Since we scrape regularly, this can
+# remain small.
+BUILDKITE_GRAPHQL_BUILDS_PER_PAGE = 50
+
 @dataclass
 class JobMetrics:
     job_name: str
@@ -70,6 +83,170 @@ class GaugeMetric:
     time_ns: int
 
 
+def buildkite_fetch_page_build_list(
+    buildkite_token: str, after_cursor: str = None
+) -> list[dict[str, str]]:
+    """Fetches a page of the build list using the GraphQL BuildKite API.
+    Returns the BUILDKITE_GRAPHQL_BUILDS_PER_PAGE last running/queued builds,
+    or the BUILDKITE_GRAPHQL_BUILDS_PER_PAGE running/queued builds
+    older than the one pointer by |after_cursor| if provided.
+    The |after_cursor| value is taken from the previous page returned by the
+    API.
+    Args:
+      buildkite_token: the secret token to authenticate GraphQL requests.
+      after_cursor: cursor after which to start the page fetch.
+    Returns:
+      The most recent builds after cursor (if set) with the following format:
+      [
+        {
+            "cursor": <value>,
+            "number": <build-number>,
+        }
+      ]
+    """
+
+    BUILDKITE_GRAPHQL_QUERY = """
+    query OrganizationShowQuery {{
+      organization(slug: "llvm-project") {{
+        pipelines(search: "Github pull requests", first: 1) {{
+          edges {{
+            node {{
+              builds (state: [RUNNING, SCHEDULED, CREATING], first: {PAGE_SIZE}, after: {AFTER}) {{
+                edges {{
+                  cursor
+                  node {{
+                    number
+                  }}
+                }}
+              }}
+            }}
+          }}
+        }}
+      }}
+    }}
+    """
+    data = BUILDKITE_GRAPHQL_QUERY.format(
+        PAGE_SIZE=BUILDKITE_GRAPHQL_BUILDS_PER_PAGE,
+        AFTER="null" if after_cursor is None else '"{}"'.format(after_cursor),
+    )
+    data = data.replace("\n", "").replace('"', '\\"')
+    data = '{ "query": "' + data + '" }'
+    url = "https://graphql.buildkite.com/v1"
+    headers = {
+        "Authorization": "Bearer " + buildkite_token,
+        "Content-Type": "application/json",
+    }
+    r = requests.post(url, data=data, headers=headers)
+    data = r.json()
+    # De-nest the build list.
+    if "errors" in data:
+        logging.info("Failed to fetch BuildKite jobs: {}".format(data["errors"]))
+        return []
+    builds = data["data"]["organization"]["pipelines"]["edges"][0]["node"]["builds"][
+        "edges"
+    ]
+    # Fold cursor info into the node dictionnary.
+    return [{**x["node"], "cursor": x["cursor"]} for x in builds]
+
+
+def buildkite_get_build_info(build_number: str) -> dict:
+    """Returns all the info associated with the provided build number.
+    Note: for unknown reasons, graphql returns no jobs for a given build,
+    while this endpoint does, hence why this uses this API instead of graphql.
+      Args:
+        build_number: which build number to fetch info for.
+      Returns:
+        The info for the target build, a JSON dictionnary.
+    """
+
+    URL = "https://buildkite.com/llvm-project/github-pull-requests/builds/{}.json"
+    return requests.get(URL.format(build_number)).json()
+
+
+def buildkite_get_incomplete_tasks(buildkite_token: str) -> list:
+    """Returns all the running/pending BuildKite builds.
+    Args:
+     buildkite_token: the secret token to authenticate GraphQL requests.
+     last_cursor: the cursor to stop at if set. If None, a full page is fetched.
+    """
+    output = []
+    cursor = None
+    while True:
+        page = buildkite_fetch_page_build_list(buildkite_token, cursor)
+        if len(page) == 0:
+            break
+        cursor = page[-1]["cursor"]
+        output += page
+    return output
+
+
+def buildkite_get_metrics(
+    buildkite_token: str, previously_incomplete: set[int]
+) -> (list[JobMetrics], set[int]):
+    """Returns a tuple with:
+    - the metrics recorded for newly completed workflow jobs.
+    - the set of workflow still running now.
+
+    Args:
+     buildkite_token: the secret token to authenticate GraphQL requests.
+     previously_incomplete: the set of running workflows the last time this
+     function was called.
+    """
+
+    running_builds = buildkite_get_incomplete_tasks(buildkite_token)
+    incomplete_now = set([x["number"] for x in running_builds])
+    output = []
+
+    for build_id in previously_incomplete:
+        if build_id in incomplete_now:
+            continue
+
+        info = buildkite_get_build_info(build_id)
+        metric_timestamp = dateutil.parser.isoparse(info["finished_at"])
+        for job in info["jobs"]:
+            # Skip this job.
+            if job["name"] not in BUILDKITE_WORKFLOW_TO_TRACK:
+                continue
+
+            created_at = dateutil.parser.isoparse(job["created_at"])
+            scheduled_at = dateutil.parser.isoparse(job["scheduled_at"])
+            started_at = dateutil.parser.isoparse(job["started_at"])
+            finished_at = dateutil.parser.isoparse(job["finished_at"])
+
+            job_name = BUILDKITE_WORKFLOW_TO_TRACK[job["name"]]
+            queue_time = (started_at - scheduled_at).seconds
+            run_time = (finished_at - started_at).seconds
+            status = bool(job["passed"])
+
+            # Grafana will refuse to ingest metrics older than ~2 hours, so we
+            # should avoid sending historical data.
+            metric_age_mn = (
+                datetime.datetime.now(datetime.timezone.utc) - metric_timestamp
+            ).total_seconds() / 60
+            if metric_age_mn > GRAFANA_METRIC_MAX_AGE_MN:
+                logging.info(
+                    f"Job {job['name']} from workflow {build_id} dropped due"
+                    + f" to staleness: {metric_age_mn}mn old."
+                )
+                continue
+
+            metric_timestamp_ns = int(metric_timestamp.timestamp()) * 10**9
+            workflow_id = build_id
+            workflow_name = "Github pull requests"
+            output.append(
+                JobMetrics(
+                    job_name,
+                    queue_time,
+                    run_time,
+                    status,
+                    metric_timestamp_ns,
+                    workflow_id,
+                    workflow_name,
+                )
+            )
+
+    return output, incomplete_now
+
 def github_get_metrics(
     github_repo: github.Repository, last_workflows_seen_as_completed: set[int]
 ) -> tuple[list[JobMetrics], int]:
@@ -276,23 +453,34 @@ def upload_metrics(workflow_metrics, metrics_userid, api_key):
 def main():
     # Authenticate with Github
     github_auth = Auth.Token(os.environ["GITHUB_TOKEN"])
+    buildkite_token = os.environ["BUILDKITE_TOKEN"]
     grafana_api_key = os.environ["GRAFANA_API_KEY"]
     grafana_metrics_userid = os.environ["GRAFANA_METRICS_USERID"]
 
     # The last workflow this script processed.
     # Because the Github queries are broken, we'll simply log a 'processed'
     # bit for the last COUNT_TO_PROCESS workflows.
     gh_last_workflows_seen_as_completed = set()
+    # Stores the list of pending/running builds in BuildKite we need to check
+    # at the next iteration.
+    bk_incomplete = set()
 
     # Enter the main loop. Every five minutes we wake up and dump metrics for
     # the relevant jobs.
     while True:
         github_object = Github(auth=github_auth)
         github_repo = github_object.get_repo("llvm/llvm-project")
 
-        metrics, gh_last_workflows_seen_as_completed = github_get_metrics(
+        gh_metrics, gh_last_workflows_seen_as_completed = github_get_metrics(
             github_repo, gh_last_workflows_seen_as_completed
         )
+        gh_metrics = []
+
+        bk_metrics, bk_incomplete = buildkite_get_metrics(
+            buildkite_token, bk_incomplete
+        )
+
+        metrics = gh_metrics + bk_metrics
         upload_metrics(metrics, grafana_metrics_userid, grafana_api_key)
         logging.info(f"Uploaded {len(metrics)} metrics")