lein-essthree

Leiningen plugin for easy S3 project deployment and dependency resolution

Just add lein-essthree to your project plugins and you're ready to configure and deploy.

Another S3 lein plugin?

There are already a handful of leiningen plugins to deploy various project types and artifacts to S3, as well as maven wagon plugins to resolve dependencies hosted in S3 buckets:

• Directory contents - lein-s3-static-deploy
• Clojure library - s3-wagon-private, lein-aws-maven, and lein-maven-s3-wagon
• Uberjar - lein-deploy-app and lein-s3-uberjar-release

The goal of lein-essthree is to unify the functionality of the above plugins, while also addressing the following issues:

1. All of the above plugins handle AWS credentials inconsistently. Some require the credentials in the project.clj map, some designate special files, some respect the AWS SDK conventions, etc. Almost none of them handled EC2 IAM roles.
2. Most of the above use different means of AWS API access. Some pull in the native AWS Java SDK, some shell out to command line programs like s3cmd, some use libraries like clj-aws-s3 which are going stale, etc.
3. Some of the above are either un-maintained, don't have much documentation, or both.

In trying to deploy various lein projects to S3 through a CI/CD service, I encountered friction due to the above issues. As such, I wanted a comprehensive S3 deployment plugin which was up-to-date, well documented, and which respected the canonical credential provider chain currently used by the AWS SDK.

Configuration

AWS Credentials

Using the awesome amazonica library, lein-essthree is able to support all of the credential providers supported by the Java AWS SDK. See the docs for full details, but in short:

1. Configuration in project.clj - :essthree {:deploy {:aws-creds {:access-key-id "access-key-id" :secret-access-key "secret-access-key"}}}
2. Environment Variables – AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
3. Java System Properties – aws.accessKeyId and aws.secretKey
4. The default credential profiles file – ~/.aws/credentials
5. Instance profile credentials – Used to pass IAM role credentials to EC2 instances

Credentials will be preferred in the order listed above. Note that while setting the values directly from project.clj is supported, it's not recommended outside of some limited development and testing scenarios.

Directory

This configuration will deploy a local directory structure to S3. lein-essthree will attempt to synchronize the two directory structures with as few API calls as possible, comparing MD5 checksums for all mutual files and only uploading those which have changed.

:essthree
    {:deploy {:type       :directory
              :bucket     "essthree.directory-test"
              :local-root "essthree-local/"
              ;; :path       "test/path/"
              ;; :aws-creds  {:access-key-id     "access-key"
              ;;              :secret-access-key "secret-key"}
              }}

Library

This configuration will transparently configure and add appropriate deploy repository entries to the project.clj configuration before passing the deployment off to the built-in lein deploy task. At that point, the deploy task will rely on the Spring project's S3 Maven wagon plugin to handle the actual deployment, which is included and configured with lein-essthree.

All of the optional configuration parameters for :deploy-repositories are supported.

:essthree
    {:deploy {:type          :library
              :bucket        "essthree.library-test"
              ;; :snapshots     true
              ;; :sign-releases true
              ;; :checksum      :fail
              ;; :update        :always
              ;; :path          "test/path/"
              ;; :aws-creds     {:access-key-id     "access-key"
              ;;                 :secret-access-key "secret-key"}
              }}

Uberjar

This configuration will compile and upload an application uberjar to S3. The uberjar compilation is handled by the built-in lein uberjar task. By default, the uberjar artifact will be uploaded to S3 with using the <project-name>-<version>-standalone.jar naming convention, but this can be optionally overridden in the essthree config.

:essthree
    {:deploy {:type          :uberjar
              :bucket        "essthree.uberjar-test"
              ;; :artifact-name "essthree-test.jar"
              ;; :path          "test/path/"
              ;; :aws-creds     {:access-key-id     "access-key"
              ;;                 :secret-access-key "secret-key"}
              }}

Repository

Along with the deployment configurations outlined above, a :repository configuration can be specified. This will cause a lein-essthree middleware function to configure and add the appropriate entries to the project's repositories for dependency resolution. Any other plugins or tasks which then handle dependency resolution, including the built-in lein tasks, will be able to resolve any dependencies hosted on S3.

All of the optional configuration parameters for :repositories are supported.

:essthree
    {:repository {:bucket        "essthree.repository-test"
                  ;; :snapshots     true
                  ;; :sign-releases true
                  ;; :checksum      :fail
                  ;; :update        :always
                  ;; :path          "test/path/"
                  ;; :aws-creds     {:access-key-id     "access-key"
                  ;;                 :secret-access-key "secret-key"}
                  }}

Usage

Once the lein-essthree configuration has been added to project.clj, just run:

$ lein essthree

Credits

Many thanks to Revcaster and The Rainmaker Group for supporting contributions to the open-source Clojure community.

License

Copyright © 2015 Dylan Paris

Distributed under the MIT License.