Tag Archives: Google App Engine flexible

Makefile – Clean App Engine flexible environment

One of the more interesting quirks of App Engine flexible environment is that App Engine launches Compute Engine virtual machines that you can’t spin down directly. The way to spin down App Engine flex is to delete all versions of the app.  This will close down all of the VMs, and shut down your App Engine app.

You can do it manually through the web interface, you can do it manually by listing versions in gcloud then deleting them, or you can have a Makefile do it for you.

First I use the trick I wrote about capturing dynamic data from gcloud. Then I pipe that to a Makefile command that will delete the versions.

Note that I add -q to the command because I don’t want to be prompted; I just want them gone.

Makefile – Get dynamic values from gcloud

Most of the time when I create something in my environment on Google Cloud Platform, I give it a specific name.  For example, I create servers and call them “ThingIWillReferenceLaterWhenIDeleteYou” or more boringly, “Server1.”

Having set names, as I alluded to, makes it easier to clean up after yourself. But there are some cases when you cannot name things when they are created. So it would be nice to get a list of these names. For example, App Engine flexible environment versions for cleaning up after a test.

You can get a list of them with this command:

Which yields this:

Now normally I would have to add extra code to my Makefile to rip out the version names.

But gcloud actually has a robust formatting tool. So instead of running the command above I can run:

And get the JSON representation, which looks like this:

Using a JSON parser might make this easier, but there is an even easier way:

Which yields:

What will this do?

It will list just the value of version.id and it will separate each record it returns with a ” “, not a line break.  This allows me to drop this generated list into any command that takes multiple names and run them. The gcloud CLI takes multiple arguments in this way. 

So to make this applicable to Makefiles I have to do one more thing – take this data and put it in a variable.

Here we are, ready to use this variable in other Make commands. This works for most of the other places in GCP where you see random values spitting out, like IP forwarding rules, and GKE nodes, to name two. 

To learn more about how to filter and format your gcloud commands, check out the Google Cloud Platform Blog.