SBT AutoPlugin to publish Docker applications to Elastic Beanstalk
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README.md

Build Status Maven Central License

sbt-elastic-beanstalk

SBT plugin providing support for publishing Docker applications to Amazon Elastic Beanstalk.

Supports AWS Dockerrun file versions 1 and 2.

Version 2 can be used to expose multiple service ports for a single or multi container image.

Installation

Add the following to you project/plugins.sbt file

addSbtPlugin("com.dbrsn" % "sbt-elastic-beanstalk" % "0.3.1")

Plugin Configuration

See ElasticBeanstalkPlugin.scala for configuration options and default values.

Plugin Tasks

The plugin provides the following tasks

  • ebsStageDockerrunFiles - stages dockerrun files to project-name/target/aws/
  • ebsPublishDockerrunFiles - publishes dockerrun files to S3
  • ebsPublishAppVersions - publish current application version to elasticbeanstalk

ebsStageDockerrunFiles

Use this task to locally inspect the dockerrun files to be published to AWS.

Dockerrun files will be written to project-name/target/aws

ebsPublishDockerrunFiles

This task publishes the dockerrun files to the configured S3 bucket.

ebsPublishAppVersions

This task associates the application version with the dockerrun files which then makes them available to elastic beanstalk for depoloyment.

This step depends on ebsPublishDockerrunFiles which must be run first.

Dockerrun files

Dockerrun files contain JSON formatted configuration, and are specific to Elastic Beanstalk. They describe how to deploy a docker container as an Elastic Beanstalk application.

Dockerrun V1

Version 1 should typically be used to define single container docker applications that expose a single port.

Single container applications that need to expose multiple ports should use the V2 specification instead.

See AWS Dockerrun V1 for further information regarding the V1 format.

Dockerrun V2

Version 2 defines applications with

  • one or more docker containers
  • more than one service port

By default the plugin supports a single container docker application exposing multiple service ports.

Version 2 includes a mandatory container memory allocation which is set automatically according to the AWS Instance type.

Deploying to a single instance type

If your environments all use the same EC2 instance type you can configure this as follows

ebsContainerMemory := 1024,         // Memory expressed in MiB
ebsEC2InstanceTypes := Set.empty    // Instance types can be omitted

Note - memory must be set to half the RAM for your instance. See A note about memory below.

You can also follow the steps for multiple instance types below and configure a single instance type instead.

Deploying to multiple instance types

If you deploy to environments with multiple instance types you can configure this via the ebsEC2InstanceTypes property as follows

ebsEC2InstanceTypes := Set(T2.Micro, T2.Small, T2.Medium, T2.Large)

Note - the ebsContainerMemory property will be ignored and predefined memory settings defined in EC2InstanceTypes will be used instead.

A dockerrun file will be generated for each instance type you declare with filenames of the form appVersion-instanceType.json. You can verify this locally by running the ebsStageDockerrunFiles task.

Example list of dockerrun files for the instance types configured above

./onboarding-service/target/aws/0.1.36-t2.large.json
./onboarding-service/target/aws/0.1.36-t2.medium.json
./onboarding-service/target/aws/0.1.36-t2.micro.json
./onboarding-service/target/aws/0.1.36-t2.small.json

Sample dockerrun file for an application exposing 3 service ports running on a t2 small instance.

{
  "AWSEBDockerrunVersion": 2,
  "authentication": {
    "bucket": "ovo-docker-apps",
    "key": ".dockercfg"
  },
  "containerDefinitions": [
    {
      "name": "onboarding-service",
      "image": "ovotech/onboarding-service:0.1.36",
      "memory": 1024,
      "essential": true,
      "portMappings": [
        {
          "hostPort": 80,
          "containerPort": 8080
        },
        {
          "hostPort": 8081,
          "containerPort": 8081
        },
        {
          "hostPort": 2551,
          "containerPort": 2551
        }
      ]
    }
  ]
}

A note about memory

In the example above we see that memory is set to 1024MiB. However a T2 Small instance has 2048MiB.

The plugin must set the memory value here to half the available amount because this value is passed to the docker run command via the -m option. By default docker will set the cgroup configuration value memory.memsw.limit_in_bytes to double the value passed in via the -m parameter.

For this reason we must specify half the amount we actually want to allocate.

The plugin uses memory values defined in EC2InstanceTypes which assume that a single application wishes to be allocated all memory available on a given instance.

Refer to links at the end of this README for further information.

See AWS Dockerrun V2 for further information regarding the V2 format.

Build Pipeline

See sbt-elastic-beanstalk

See Also