This tool allows you to migrate an App Engine service's version gradually from one version to another.
Normally, you can migrate an App Engine service's version by gcloud app versions migrate command or from the web console, but the speed of migration is out of control, sometimes it ends very fast.
With this tool, you can control how fast migration proceeds precisely.
$ go get -u github.com/yfuruyama/appmig
This tool uses gcloud to manipulate App Engine services.
If you have not installed it yet, please install it before.
$ appmig --project=PROJECT --service=SERVICE --version=VERSION --rate=RATE --interval=INTERVAL
Please look at appmig --help for more details.
Following example shows migration from v1 to v2 happens with steps 1% -> 10% -> 25% -> 50% -> 100% in 30 seconds interval.
$ appmig --project=mytest --service=default --version=v2 --rate=1,10,25,50,100 --interval=30
Checking existence of version v2... : OK
Checking current serving version... : v1(100%)
Migrate traffic: project=mytest, service=default, from=v1, to=v2
Do you want to continue? [Y/n] Y
Migrating from v1(99%) to v2(1%)... : DONE
Waiting 30 seconds...
Migrating from v1(90%) to v2(10%)... : DONE
Waiting 30 seconds...
Migrating from v1(75%) to v2(25%)... : DONE
Waiting 30 seconds...
Migrating from v1(50%) to v2(50%)... : DONE
Waiting 30 seconds...
Migrating from v1(0%) to v2(100%)... : DONE
Finish migration!
If you are migrating from v1 to v2, this tool iterates gcloud app services set-traffic --splits=<v1=x%,v2=y%> to increase the v2 traffic gradually.
Each step of the execution increases the ratio of v2 traffic according to the --rate option.
Note that traffic splitting is held by the IP address of the requesting client.