lein-beanstalk

Leiningen plugin for Amazon's Elastic Beanstalk.

Prerequisites

You will need an Amazon Web Services account, and know your account key and secret key.

You will also need to be signed up for Elastic Beanstalk.

Basic Configuration

To use lein-beanstalk, you'll need to add a few additional values to your project.clj file.

First, add lein-beanstalk as a plugin:

:plugins [[lein-beanstalk "0.2.6"]]

or, if you're using a version of Leiningen prior to 1.7.0, add it to your :dev-dependencies:

:dev-dependencies [[lein-beanstalk "0.2.6"]]

Then add a lein-beanstalk-credentials definition to your ~/.lein/init.clj file that contains your AWS credentials:

(def lein-beanstalk-credentials
  {:access-key "XXXXXXXXXXXXXXXXXX"
   :secret-key "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY"})

Or, if you're using Leiningen 2, you can add the credentials to your ~/.lein/profile.clj file:

{:user
 {:aws {:access-key "XXXXXXXXXXXXXXXXXX"
        :secret-key "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY"}}}

Finally, lein-beanstalk uses lein-ring for packaging your application, so all of lein-ring's configuration applies as well. At a minimum, you'll need to your project.clj a reference to your application's top-level handler, e.g.:

:ring {:handler hello-world.core/handler}

See the documentation for lein-ring for more about the options it provides.

Deploy

You should now be able to deploy your application to the Amazon cloud using the following command:

$ lein beanstalk deploy development

Info

To get information about the application itself run

$ lein beanstalk info
Application Name : myapp
Description      : My Awesome Compojure App
Last 5 Versions  : 0.1.0-20110209030504
                   0.1.0-20110209030031
                   0.1.0-20110209025533
                   0.1.0-20110209021110
                   0.1.0-20110209015216
Created On       : Wed Feb 09 03:00:45 EST 2011
Updated On       : Wed Feb 09 03:00:45 EST 2011
Deployed Envs    : development (Ready)
                   staging (Ready)
                   production (Terminated)

and information about a particular environment execute

$ lein beanstalk info development
Environment Id   : e-lm32mpkr6t
Application Name : myapp
Environment Name : development
Description      : Default environment for the myapp application.
URL              : development-feihvibqb.elasticbeanstalk.com
LoadBalancer URL : awseb-myapp-46156215.us-east-1.elb.amazonaws.com
Status           : Ready
Health           : Green
Current Version  : 0.1.0-20110209030504
Solution Stack   : 32bit Amazon Linux running Tomcat 6
Created On       : Tue Feb 08 08:01:44 EST 2011
Updated On       : Tue Feb 08 08:05:01 EST 2011

Shutdown

To shutdown an existing environment use the following command

$ lein beanstalk terminate development

This terminates the environment and all of its resources, i.e. the Auto Scaling group, LoadBalancer, etc.

Cleanup

To remove any unused versions from the S3 bucket run

$ lein beanstalk clean

Configuration

AWS Credentials

The Amazon Web Services account key and secret key should be put into a lein-beanstalk-credentials definition in your ~/.lein/init.clj file:

(def lein-beanstalk-credentials
  {:access-key "XXXXXXXXXXXXXXXXXX"
   :secret-key "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY"})

Keeping your credentials out of your project.clj file and out of your project in general helps ensure you don't accidentally commit your credentials to github et al.

However, If you want to deploy your application using beanstalk from an environment like Jenkins, where you don't have control over the user, you can export the credential to the environment from the build script, and inside your project.clj, do:

(defproject my-project "0.1.0"
    :description ...
    :aws {
        :access-key ~(System/getenv "AWS_ACCESS_KEY")
        :secret-key ~(System/getenv "AWS_SECRET_KEY")})

Environments

Elastic Beanstalk environments can be defined in multiple ways in the project.clj file.

If no environments are specified, lein-beanstalk will create three default environments

• development (with CNAME prefix myapp-development)
• staging (with CNAME prefix myapp-staging)
• production (with CNAME prefix myapp)

To override the default behavior, add an :aws key to your project.clj file, either with :environments mapped to a vector of envionment symbols:

:aws {:beanstalk {:environments [dev demo prod]
                  ...}
      ...}

or to a vector of maps

:aws {:beanstalk {:environments [{:name "dev"}
                                 {:name "demo"}
                                 {:name "prod"}]
                  ...}
      ...}

Given either of the above configurations, the following two environents will be created:

• dev (with CNAME prefix myapp-dev)
• demo (with CNAME prefix myapp-demo)
• prod (with CNAME prefix myapp-prod)

The second option allows one to specify the CNAME prefix for each environment

:aws {:beanstalk {:environments [{:name "dev"
                                  :cname-prefix "myapp-development"}
                                 {:name "staging"
                                  :cname-prefix "myapp-demo"}
                                 {:name "prod"
                                  :canme-prefix "myapp"}]
                  ...}
      ...}

By default the CNAME prefix is <project-name>-<environment>.

Environment Variables

You can specify environment variables that will be added to the system properties of the running application, per beanstalk environment:

:aws
{:beanstalk
 {:environments
  [{:name "dev"
    :cname-prefix "myapp-dev"
    :env {"DATABASE_URL" "mysql://..."}}]}}

If the environment variable name is a keyword, it is upper-cased and underscores ("_") are substituted for dashes ("-"). e.g. :database-url becomes "DATABASE_URL".

S3 Buckets

Amazon Elastic Beanstalk uses Amazon Simple Storage Service (S3) to store the versions of the application. By default lein-beanstalk uses lein-beanstalk.<project-name> as the S3 bucket name.

To use a custom bucket, specify it in the project.clj file:

:aws {:beanstalk {:s3-bucket "my-private-bucket"
                  ...}}

Regions

You can specify the AWS region of to deploy the application to through your project.clj file:

:aws {:beanstalk {:region "eu-west-1"}}

The following regions are recognized:

• us-east-1 (default)
• ap-northeast-1
• eu-west-1
• us-west-1
• us-west-2

Trouble-Shooting

Q: Why does my deployed web application still shows up as 'red' in the Elastic Beanstalk console?

A: Elastic Beanstalk sends a HTTP HEAD request to '/' to check if the application is running. Simply add the necessary handling to the application. e.g. for Compojure add

(HEAD "/" [] "")