drone-autoscaler
This app scales a Drone CI agent cluster up or down based on build volume.
It was created because the autoscaler provided by Drone has several limitations:
- It doesn't support AWS's Autoscaling Groups (ASGs). Instead, it creates standalone ec2 instances.
drone-autoscaler
is designed to simply manipulate the desired capacity of the ASG that manages your Drone Agents.
- It installs & configures an agent on a newly created machine.
drone-autoscaler
assumes that any new machine in the agent ASG is already provisioned.
- It waits for upto 60 minutes for running builds to finish on an agent marked for termination.
drone-autoscaler
only terminates nodes that aren't running any builds.
Usage
Setup
This app assumes that your Drone agent cluster is managed by an AWS Autoscaling Group.
Configuration
The app's behaviour can be configured using various parameters
Environment variable |
Required |
DRONE_AGENT_MAX_BUILDS |
Yes |
DRONE_AGENT_AUTOSCALING_GROUP |
Yes |
DRONE_SERVER_HOST |
Yes |
DRONE_SERVER_AUTH_TOKEN |
Yes |
SCALER_PROBE_INTERVAL |
No |
SCALER_LOG_FORMAT |
No |
SCALER_DEBUG |
No |
SCALER_DRY |
No |
DRONE_AGENT_MIN_RETIREMENT_AGE |
No |
DRONE_AGENT_MIN_COUNT |
No |
DRONE_SERVER_PROTO |
No |
DRONE_BUILD_PENDING_MAX_DURATION |
No |
DRONE_BUILD_RUNNING_MAX_DURATION |
No |
See config.go for parameter descriptions
Running
- Download a pre-compiled binary from the releases page or build it from code using
make dist
.
- Set the required configuration parameters via environment variables.
- Run the acquired binary.
Developing
The recommended way to run the app in development mode is to use the following configuration:
SCALER_LOG_FORMAT=text
SCALER_DEBUG=true
DRONE_BUILD_PENDING_MAX_DURATION="4h"
DRONE_BUILD_RUNNING_MAX_DURATION="1h"
# Outputs what the app plans to do, without making any changes
# to the actual infrastructure. This allows you to point the
# app to the actual agent ASG in development mode without
# worrying about accidental destruction of nodes.
SCALER_DRY=true
# If AWS profile is configured, use these params to load creds
# and all profile configuration.
AWS_PROFILE=my_profile
AWS_SDK_LOAD_CONFIG=true
Run make fmt
to format the Go code. To run tests, use make test
.
To create a new release, bump the app version in main
and run make dist
.