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Deploying Libraries

Getting your library into Clojars is fairly straightforward as is documented near the end of the Leiningen tutorial. However, deploying is not always that straightforward.

Private Repositories

There may be times when you want to make a library available to your team without making it public. This is best done by setting up a private repository. The simplest kind of private repository is a web server pointed at a directory full of static files. You can use a file:/// URL in your :repositories to deploy that way if the directory is local to the machine on which Leiningen is running. Amazon S3 buckets are another simple choice; you can deploy to S3 buckets using S3 wagon private.

Alternatively you can run a private repository on your own server. Both Archiva and Nexus provide this as well as proxying to other repositories, so you can set :omit-default-repositories in project.clj, and dependency downloads will speed up by quite a bit with only one server to check.

The private server will need to be added to the :repositories listing in project.clj. Archiva and Nexus offer separate repositories for snapshots and releases, so you'll want two entries for them:

:repositories [["snapshots" ""]
               ["releases" ""]]

If you are are deploying to a repository that is only used for deployment and never for dependency resolution, then it should be specified in a :deploy-repositories slot instead of included in the more general-purpose :repositories map; the former is checked by lein deploy before the latter. Deployment-only repositories useful across a number of locally developed projects may also be specified in the :user profile in ~/.lein/profiles.clj:

{:user {:deploy-repositories [["internal" ""]]}}


Deploying and reading from private repositories needs authentication credentials. Check your repository's documentation for details, but you'll usually need to provide a :username and :password or :passphrase. Leiningen will prompt you for a password if you haven't set up credentials, but it's convenient to set it so you don't have to re-enter it every time you want to deploy. You will need gpg installed and a key pair configured.

If you specify a :creds :gpg entry in one of your :repositories settings maps, Leiningen will decrypt ~/.lein/credentials.clj.gpg and use that to find the proper credentials for the given repository.

:repositories [["releases" {:url ""
                            :creds :gpg}]]

First write your credentials map to ~/.lein/credentials.clj like so:

{#"blueant" {:password "locative1"}
 {:username "milgrim" :password "locative1"}
 {:username "AKIAIN..." :passphrase "1TChrGK4s..."}}

If you don't have a key pair yet, it's easy to generate one. The defaults should serve you well, but be sure to pick a strong passphrase.

$ gpg --gen-key

Then encrypt it with gpg:

$ gpg --default-recipient-self -e \
    ~/.lein/credentials.clj > ~/.lein/credentials.clj.gpg

Remember to delete the plaintext credentials.clj once you've encrypted it. Due to a bug in gpg you currently need to use gpg-agent and have already unlocked your key before Leiningen launches, but with gpg-agent you only have to enter your passphrase once per login.

On some systems you will be prompted for your GPG passphrase if you haven't entered it. If yours does not, you can install Keychain, which provides this functionality portably. Your key will also be used for signing artifacts if the version is not a snapshot, so you may be asked for the passphrase multiple times if the agent is not configured. To disable signing of releases, set :sign-releases to false in the :repositories entry you are targeting.

Unattended builds can specify :env instead of :gpg in the repository specification to have credentials looked up in the environment. For example, specifying :password :env will cause Leiningen to look up (System/getenv "LEIN_PASSWORD") for that value. You can control which environment variable is looked up for each value by using a namespaced keyword, like so:

:repositories [["releases" {:url ""
                            :username :env/archiva_username
                            :passphrase :env/archiva_passphrase}]]

Finally, you can opt to load credentials from the environment or GPG credentials by using a vector of :gpg and :env/* values to define the priority of each:

:repositories [["releases" {:url ""
                            :username [:gpg :env/archiva_username]
                            :passphrase [:gpg :env/archiva_passphrase]}]]

In this example, both :username and :password will be looked up in ~/.lein/credentials.clj.gpg first, and only if a value is not available there will the ARCHIVA_* env vars be checked. This allows you to avoid creating profiles just to use different credential sources in e.g. a local development environment vs. a centralized build environment.


Once you've set up a private repository and configured project.clj appropriately, you can deploy to it:

$ lein deploy [repository-name]

If the project's current version is a SNAPSHOT, it will default to deploying to the snapshots repository; otherwise it will default to releases.

Deploying to Maven Central

Deploying your libraries and other artifacts to Maven Central is often desirable. Most tools that use the Maven repository format (including Leiningen, Gradle, sbt, and Maven itself) include Maven Central or one of its mirrors as a default repository for resolving project dependencies. So, deploying your libraries to Maven Central offers the widest distribution, especially if your users are likely to be in languages other than Clojure.

Thankfully, Leiningen can deploy your libraries to Maven Central, with a few additional bits of configuration. All of the guidance about deploying to private repositories laid out above applies; but, here's a step-by-step recipe from start to finish:

  1. Register an account and groupId on; refer to this for details on how to get registered (you can ignore most of the info on that page regarding configuring Maven and/or ant, since we'll not be touching those tools). Note that all artifacts you deploy to OSS will need to use the groupId(s) you choose, so your project coordinates should be set up to match; e.g.:
(defproject "x.y.z" ...)
  1. Add your credentials for to your ~/.lein/credentials.clj.gpg file. Something like this will do:
 {:username "username" :password "password"}}

Refer to the instructions earlier on this page for how to encrypt a plain-text credentials.clj using GPG.

  1. Add the OSS deployment repository endpoints to your project.clj, e.g.:
:deploy-repositories [["releases" {:url ""
                                   :creds :gpg}
                       "snapshots" {:url ""
                                    :creds :gpg}]]
  1. Conform to OSS' requirements for uploaded artifacts' pom.xml files; all you need to do is make sure the following slots are populated properly in your project.clj:

Examples of OSS-acceptable values for these entries can be seen in this project.clj file. Note that all of them should be appropriate for your project; blind copy/paste is not appropriate here.

  1. Run lein deploy. Leiningen will push all of the files it would otherwise send to Clojars or your other private repository to the proper OSS repository (either releases or snapshots depending on whether your project's version number has -SNAPSHOT in it or not).

  2. If you're deploying a release, log in to, and close and release/promote your staged repository. (This manual step will eventually be automated through the use of a plugin.) The release will show up in OSS' releases repository immediately, and sync to Maven Central on the next cycle (~ 1-4 hours usually).

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