Blog about Full Stack Web Applications
Google App Engine Pro Tip: Use Git Commit Hash as Version
Google App Engine (GAE) is a serverless approach to quickly ship your code. Typically, when you want to deploy, you only need to run one command:
gcloud app deploy
In the Google Cloud Console, you will see a new version of your app appearing, the traffic will be migrated to that new version, and the old version will be shut down.
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By default, versions have a timestamp as name, e.g. 20201204t131734. However, when you want to know what code actually has been deployed, you can only guess it based on that timestamp.
A better approach would be to use your Git commit hash as version. The time of deploy is known anyway (see 5th column in the image). In bash, you can do:
In this example, commit_hash is the short version of the hash of the commit you have currently checked-out.
Of course, this would not make sense if you still have uncommitted changes. To block this, you could use a deploy script, named e.g. deploy.sh, with following content:
Now you know exactly what code has been deployed based on the version name.
There is one remaining caveat: you can still have ignored files. To avoid this, make sure your .gcloudignore file contains at least the patterns of your .gitignore file.
Update: there is a bug at Google (see issue tracker) sometimes causing the version to be parsed as a float, resulting in the deploy to fail. Example: 367e5893 is interpreted as 367·10⁵⁸⁹³ and further cast to Infinity. Workaround is to add a prefix for each version (e.g. v-367e5893).