Wait for, acquire, and release a distributed lock via S3 storage.
- uses: aws-actions/configure-aws-credentials@v4
with:
# ...
# This blocks until the lock is acquired, or errors if timeout is reached
- uses: freckle/aws-s3-lock-action@v1
with:
# Required
bucket: an-existing-s3-bucket
# Optional, defaults shown
# name: {workflow}/{job}
# expires: 15m
# timeout: {matches expires}
# timeout-poll: 5s
# context: "{workflow} #{run}"
- run: echo "Lock held, do work here"
The lock is released (the S3 object deleted) in our Post step, which provides a pretty robust guarantee of release. Expired locks are ignored (not deleted), so it's recommended you put a Lifecyle policy on the Bucket to clean them up after some time.
See action.yml for a complete list of inputs and outputs.
This tool implements a version of the locking algorithm described in this StackOverflow answer.
-
Upload a lock object to S3 at
<name>.<created>.<uuid>.<expires>All time values are milliseconds since epoch.
-
List all other lock objects (prefix
<name>.)Filter out any expired keys (looking at
expires) and sort, which implicitly means bycreatedthenuuidas desired. -
If the first one (i.e. oldest) is our own, we've acquired the lock
-
If not, we lost the race; remove our object, wait, and try again
Each time we attempt to acquire the lock, we create a new key name (e.g.
<created> and <expires> both change), this effectively loses our "place in
line" but ensures that expiry is measured from time of acquisition and not time
of first attempt. There are trade-offs either way, and possible room for
improvement, so this is just how we're doing it for now.
This tool is not meant to be bullet-proof. We built it for our needs and accept that there are simply no strong guarantees in this locking mechanism's operation at scale. Your mileage may vary; patches welcome.
Versioned tags will exist, such as v1.0.0 and v2.1.1. Branches will exist
for each major version, such as v1 or v2 and contain the newest version in
that series.
Given a latest version of v1.0.1,
Is this a new major version?
If yes,
git checkout main
git pull
git checkout -b v2
git tag -s -m v2.0.0 v2.0.0
git push --follow-tagsOtherwise,
git checkout main
git pull
git checkout v1
git merge --ff-only -
git tag -s -m v1.0.2 v1.0.2 # or v1.1.0
git push --follow-tags