Automatically schedule AWS resources running time
By tagging AWS resources with a schedule, possum will ensure that they are in the state that the schedule supports. It was build mainly as a cost saving technique for my personal development servers and was inspired by AWS [https://aws.amazon.com/answers/infrastructure-management/instance-scheduler/] but that solution did not support auto scaling groups and some other minor things I wanted to have.
It can optionally send change notifications to a slack room.
this highly depends on how long the lambda function is running, and the run time is dependent how many resources an AWS account has
Memory size ~ 32mb at peak
Possum runs as a go1.X lambda function triggered by a X min schedule via Cloudwatch Events.
Can only start and stop in the deployed account
note: possum cannot start or stop reserved instances
note: only tested on DBInstances, not DBClusters and other special database types
Stops auto scaling groups by zeroing out the min size and the desired capacity, during this step it also tags the auto scaling group with the current min size and desired capacity so that it can on start reset those values
Start tries to find the previous min size and desired capacity from tags set on the group by the stop stage, if those values cannot be parsed it sets the min size and desired capacity to 1.
The root directory of this project contains the possum application. However the execution via Lambda is controlled via a separate application stored in cmd/lambda.
You don't need to build the possum application itself as it is included in the lambda function of this repository.
In order to deploy your changes, you will need to package the deployment using aws cloudformation package. To simplify this process, a Makefile has been created to perform this action for you.
cd cmd/lambda
aws-vault exec <account> -- make package
This command will build the golang lambda application, combine it with the template.yml Cloudformation, and package it together to be consumed by Cloudformation.
Once you have your package build, you can push out your changes using aws cloudformation deploy functionality. To simplify this process, the Makefile contains a deploy function that does this for you.
cd cmd/lambda
aws-vault exec <account> -- make deploy
This command will tell Cloudformation to deploy the package created using make package.