Awesome

lein-v

Drive leiningen project version from git instead of the other way around.

Motivation

The lein-v plugin was driven by several beliefs:

1. Versioning should be painless in the simplest cases
2. Unique (and reproducible/commited) source should produce unique versions
3. Versioning information should live in the SCM repo -the source of source truth
4. Version information is metadata and should not be stored within the data it describes

Lein-v uses git metadata to build a unique, reproducible and semantically meaningful version for every commit. Along the way, it adds useful metadata to your project and artifacts (jar and war files) to tie them back to a specific commit. Finally, it helps ensure that you never release an irreproduceable artifact.

Task Usage

There are two lein sub-tasks within the v namespace intended for direct use:

lein v

Show the effective version of the project and workspace state.

lein v cache

Cache the effective version of the project to a file (default is version.clj) in the first source directory (typically src). It is possible to have the version cached to a file automatically by defining a prep task in your project like this:

:prep-tasks [["v" "cache" "src"]]

The lein v cache command has a variadic argument that is the following: first is the directory to output to (default to src), then the rest is the list of the output suffixes you wish and hence format (default to clj). The available suffixes are: clj, cljs, cljx, cljc and edn. You have two formats for file version output depending on the suffix:

Clojure source code: available via the clj, cljs, cljc or cljx option
EDN data structure: available via the edn option

Examples of lein v cache invocation

lein v cache src/cljs cljs
# => output only the src/cljs/version.cljs file
lein v cache src/clj clj edn
# => output the src/clj/version.clj and src/clj/version.edn file
lein v cache src edn
# => output the src/version.edn file

Example of Clojure source code version output

;; This code was automatically generated by the 'lein-v' plugin
(ns version)
(def version "0.6.40")
(def raw-version "v0.6.40")

Example of EDN version output

{:version "0.6.40", :raw-version "v0.6.40"}

Typical Use Cases of version.xxx file

Displaying application's version in logs for backends or UI screen for frontend
In Leiningen tasks you can use the project's version string in the EDN wherever you want, like in output's filename for uberjar or CLJS bundle:

~(str "target/releases/js/myapp-" (:version (clojure.edn/read-string (slurp "src/cljs/version.edn")))".min.js")

As of leiningen 2.4.1, a less intrusive means of extracting the verison (with caching to a dedicated file) is as follows:

(let [pom-properties (with-open [pom-properties-reader (io/reader (io/resource "META-INF/maven/x/x/pom.properties"))]
                       (doto (java.util.Properties.)
                         (.load pom-properties-reader)))]
  (get pom-properties "version"))

Hooks

Through the use of the Leiningen hooks functionality, lein-v ensures that leiningen's own view of the current version is updated before tasks are run. Thus this

(defproject my-group/my-project :lein-v
  :plugins [[com.roomkey/lein-v "5.0.0"]]
  ...)

becomes this:

(defproject my-group/my-project "1.0.1-2-0xabcd"
  :plugins [[com.roomkey/lein-v "5.0.0"]]
  ...)

Assuming that there is a git tag v1.0.1 on the commit HEAD~~, and that the SHA of HEAD is uniquely identified by abcd. This behavior is automatically enabled whenever lein-v finds the project version to be the keyword :lein-v.

Dependencies

In case you're using a monorepository, you could also use lein-v to determine the current version of dependencies.

Add the leiningen.v/dependency-version-from-scm middleware to your project like this:

  :middleware [leiningen.v/version-from-scm
               leiningen.v/dependency-version-from-scm
               leiningen.v/add-workspace-data]

Now, if you set the version of a dependency from your monorepo to nil (just as you would using managed-dependencies), it will be replaced with the current version from git (which is the same as the version of the project you're currently working on).

  :dependencies
  [[commons-io "2.5"]
   [example/lib-a nil]
   [example/lib-b nil]
   [org.clojure/clojure "1.8.0"]])

becomes

  :dependencies
  [[commons-io "2.5"]
   [example/lib-a "1.0.1-2-0xabcd"]
   [example/lib-b "1.0.1-2-0xabcd"]
   [org.clojure/clojure "1.8.0"]])

Support for lein release

As of version 5.0, lein-v adds support for leiningen's release task. Specifically, the lein v update task can anchor a release process that ensures that git tags are created and pushed, and that those tags conform to sane versioning expectations. To use lein release with lein-v, first modify project.clj (or your leiningen user profile) to something such as this:

:release-tasks [["vcs" "assert-committed"]
                ["v" "update"] ;; compute new version & tag it
                ["v" "push-tags"]
                ["deploy"]]

To effect version changes, lein-v's update-version task sees the versioning parameter provided to lein release and operates as follows:

current	directive	result
1.0.2	`:major`	2.0.0
1.1.4	`:minor`	1.2.0
2.5.6	`:patch`	2.5.7

In addition to incrementing the standard numeric version components, you can qualify any of the above directives with typical qualifiers like alpha, beta, rc. For example:

current	directive	result
1.0.2	`:minor-alpha`	1.1.0-alpha
4.2.8	`:major-rc`	5.0.0-RC

When the current version is a qualified version, you can increment the current qualifier, advance to the next qualifier or simply release an unqualified version. Here are some examples:

current	directive	result
1.0.2-alpha	`:alpha`	1.0.2-alpha2
1.0.2-alpha	`:beta`	1.0.2-beta
1.0.2-beta	`:rc`	1.0.2-rc
1.0.2-rc	`:rc`	1.0.2-rc2
3.2.0-rc2	`:release`	3.2.0

Snapshot versions are similar, but the resulting version is never changed.

current	directive	result
3.2.0	`:minor-snapshot`	3.3.0-SNAPSHOT
3.3.0-SNAPSHOT	`:snapshot`	3.3.0-SNAPSHOT
3.3.0-SNAPSHOT	`:release`	3.3.0

Finally, lein-v enforces some common-sense rules:

For commits without a version tag, the base version will be extended with a build number using the commit distance from HEAD to the most recent version tag (looking towards the root of the tree) and the unique SHA prefix of the commit.
You can never go backwards with versions. This includes qualifiers, which are orderd as follows:
1. alpha
2. beta
3. rc
4. snapshot
When a git repo is first used with lein-v and has no version tags, the default base version is 0.0.0, and it is reported with a distance from the root commit and the relevant SHA (0.0.0-23-0xabcd).
When tags are created in the git repo, they are prefixed with the letter 'v'.

It is still possible to do a raw lein deploy, in which case the version will be that determined by lein-v (most likely something like "1.0.1-2-0xabcd").

Note: you can provide your own implementation of many of these rules. See the source code for details on defining data types adhering to the protocols in the leiningen.v.protocols namespace. Currently there are implementations for maven (version 3) and Semantic Versioning (version 2) available.

Migrating to lein-v

When migrating an existing project.clj, you may not want your project version to reset to v0.0.0 again. You may seed a git tag for lein-v to use. In the example below, the artifact's most recent release is 1.3.2.

git tag --annotate --message "Seeding lein-v version" v1.3.12

To verify the result had the desired effect, see output of lein v version.

> lein v version
Effective version: 1.3.12 ...

References and Relevant Reading

License

Distributed under the Eclipse Public License, the same as Clojure.