Reviewing Buildkite CI logs

Julia's CI runs on Buildkite (pipeline julialang/julia-master). The public web UI requires sign-in to download raw_log, but the Buildkite frontend's JSON log endpoint is anonymously accessible for public pipelines. Recipe:

1. List failing jobs and their UUIDs (the fragment after # in the URL):

   gh pr checks <PR-number> | grep -E "fail|pending"

2. Fetch the log JSON (replace <BUILD> and <JOB-UUID>):

   curl -sS -H "Accept: application/json" \
     "https://buildkite.com/organizations/julialang/pipelines/julia-master/builds/<BUILD>/jobs/<JOB-UUID>/log" \
     -o /tmp/bk.json

   The log text lives under the JSON output field, with embedded HTML (<time> timestamps, ANSI-as-<span> colour) and entity-encoded shell output. Strip with e.g.:

   python3 -c "import json,re,html; s=json.load(open('/tmp/bk.json'))['output']; \
   s=re.sub(r'<[^>]+>','',s); print(html.unescape(s))" | tail -200

The same JSON endpoint also serves still-running jobs (partial output). Note that the top-level Build/Check/Test jobs on a PR are pipeline launchers — the actual per-platform builds are spawned as child jobs whose UUIDs only appear once they start.