This Docker container allows you to (de)register an EC2 instance with an Amazon Elastic Load Balancer Target Group.

(Inspired by: https://github.com/coreos/elb-presence)

The elbtg-presence container takes all of its configuration from environment variables.

docker run --rm --name example-presence -e AWS_ACCESS_KEY=<key> -e AWS_SECRET_KEY=<secret> -e AWS_REGION=us-east-1 -e AWS_TARGET_GROUP=ExampleTargetGroup quay.io/sfurnival/elbtg-presence

• AWS_ACCESS_KEY ... Your AWS access key
• AWS_SECRET_KEY ... Your AWS secret key
• AWS_REGION ... The AWS region that your load balancer is located in
• AWS_TARGET_GROUP ... The ARN for the desired Target Group

Usually you'll want to manage the lifecycle of your presence service using fleet. To do so, you can create a service file similar to this example:

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[Unit]
Description=Example Presence Service
BindsTo=my-service@%i.service

[Service]
TimeoutStartSec=0
ExecStartPre=-/usr/bin/docker kill %p-%i
ExecStartPre=-/usr/bin/docker rm %p-%i
ExecStartPre=/usr/bin/docker pull quay.io/sfurnival/elbtg-presence:latest
ExecStart=/usr/bin/docker run --rm --name %p-%i -e AWS_ACCESS_KEY=<key> -e AWS_SECRET_KEY=<secret> -e AWS_REGION=us-east-1 -e AWS_TARGET_GROUP=ExampleTargetGroup quay.io/sfurnival/elbtg-presence
ExecStop=/usr/bin/docker stop %p-%i

[X-Fleet]
MachineOf=my-service@%i.service

This service will deploy to the same machine as your service (MachineOf) and automatically start and stop along with it (BindsTo).