# Profiles

You can change the configuration of your project by applying various
profiles. For instance, you may want to have a few extra test data
directories on the classpath during development without including them
in the jar, or you may want to have development tools like
[Slamhound](https://github.com/technomancy/slamhound) available in
every project you hack on without modifying every single `project.clj`
you use.

By default the `:dev`, `:provided`, `:user`, `:system`, and `:base`
profiles are activated for each task, but their settings are not
propagated downstream to projects that depend upon yours. Each profile
is defined as a map which gets merged into your project map.

You can place any arbitrary key/value pairs supported by `defproject`
into a given profile and they will be merged into the project map when
that profile is activated.

The example below adds a "dummy-data" resources directory during
development and a dependency upon "expectations" that's only used for tests.

```clj
(defproject myproject "0.5.0-SNAPSHOT"
  :description "A project for doing things."
  :dependencies [[org.clojure/clojure "1.4.0"]]
  :profiles {:dev {:resource-paths ["dummy-data"]
                   :dependencies [[expectations "1.4.41"]]}})
```


## Declaring Profiles

In addition to `project.clj`, profiles also can be specified in `profiles.clj`
within the project root. Profiles specified in `profiles.clj` will override
profiles in `project.clj`, so this can be used for project-specific overrides
that you don't want committed in version control.

User-wide profiles can also be specified in
`~/.lein/profiles.clj`. These will be available in all projects
managed by Leiningen, though those profiles will be overridden by
profiles of the same name specified in the project.  System-wide
profiles can be placed in `/etc/leiningen/profiles.clj`. They are
treated the same as user profiles, but with lower precedence.

You can also define user-wide profiles within `clj`-files inside
`~/.lein/profiles.d`. The semantics within such files differ slightly
from other profile files: rather than a map of maps, the profile map
is the top-level within the file, and the name of the profile comes
from the file itself (without the `.clj` part). Defining the same
user-wide profile in both `~/.lein/profiles.clj` and in
`~/.lein/profiles.d` is considered an error.

The `:user` profile is separate from `:dev`; the latter is intended to
be specified in the project itself. In order to avoid collisions, the
project should never define a `:user` profile, nor should a user-wide
`:dev` profile be defined. Use the `show-profiles` task to list them.

If you want to access dependencies during development time for any
project place them in your `:user` profile. Your
`~/.lein/profiles.clj` file could look something like this:

```clj
{:user {:plugins [[lein-pprint "1.1.1"]]
        :dependencies [[slamhound "1.3.1"]]}}
```

## Merging

Profiles are merged by taking each key in the project map or profile
map, combining the value if it's a collection and replacing it if it's
not. Profiles specified later take precedence when replacing, just
like the `clojure.core/merge` function. The dev profile takes
precedence over user by default. Maps are merged recursively, sets are
combined with `clojure.set/union`, and lists/vectors are
concatenated. You can add hints via metadata that a given value should
take precedence (`:replace`) or defer to values from a different
profile (`:displace`) if you want to override this logic:

```clj
{:profiles {:dev {:prep-tasks ^:replace ["clean" "compile"]
                  :aliases ^:displace {"launch" "run"}}}}
```

The exception to this merge logic is that `:plugins` and `:dependencies`
have custom de-duplication logic since they must be specified as
vectors even though they behave like maps (because it only makes sense
to have a single version of a given dependency present at once). The
replace/displace metadata hints still apply though.

Remember that if a profile with the same name is specified in multiple files, 
the last one will *replace* the previous ones, no merging. (If you need to enable 
personal overrides of parts of a profile, you can use a composite profile with 
common and personal parts - something like `:dev [:dev-common :dev-overrides]`; 
you would then have just `:dev-overrides {}` in `project.clj` and override it in
`profiles.clj`.)

Another use of profiles is to test against various sets of dependencies:

```clj
(defproject swank-clojure "1.5.0-SNAPSHOT"
  :description "Swank server connecting Clojure to Emacs SLIME"
  :dependencies [[org.clojure/clojure "1.2.1"]
                 [clj-stacktrace "0.2.4"]
                 [cdt "1.2.6.2"]]
  :profiles {:1.3 {:dependencies [[org.clojure/clojure "1.3.0"]]}
             :1.4 {:dependencies [[org.clojure/clojure "1.4.0-beta1"]]}})
```

## Activating Profiles

To activate a different set of profiles for a given task, use the
`with-profile` higher-order task:

    $ lein with-profile 1.3 test :database

Multiple profiles may be combined with commas:

    $ lein with-profile qa,user test :database

Multiple profiles may be executed in series with colons:

    $ lein with-profile 1.3:1.4 test :database

The above invocations activate the given profiles in place of the
defaults. To activate a profile in addition to the defaults, prepend
it with a `+`:

    $ lein with-profile +server run

You can also use `-` to deactivate a profile.

By default all profiles will share the same `:target-path`, which can
cause problems if settings from one profile leak over into
another. It's recommended to set `:target-path` to `"target/%s"`,
which will isolate each profile set and prevent anything from bleeding over.

## Composite Profiles

Sometimes it is useful to define a profile as a combination of other
profiles. To do this, just use a vector instead of a map as the profile value.
This can be used to avoid duplication:

```clj
{:shared {:port 9229, :protocol "https"}
 :qa [:shared {:servers ["qa.mycorp.com"]}]
 :stage [:shared {:servers ["stage.mycorp.com"]}]
 :production [:shared {:servers ["prod1.mycorp.com", "prod1.mycorp.com"]}]}
```

Composite profiles are used by Leiningen internally for the `:default`
profile, which is the profile used if you don't change it using
`with-profile`. The `:default` profile is defined to be a composite of
`[:base :system :user :provided :dev]`, but you can change this in your
`project.clj` just like any other profile.

## Debugging

To see how a given profile affects your project map, use the
[lein-pprint](https://github.com/technomancy/leiningen/tree/stable/lein-pprint)
plugin:

    $ lein with-profile 1.4 pprint
    {:compile-path "/home/phil/src/leiningen/lein-pprint/classes",
     :group "lein-pprint",
     :source-path ("/home/phil/src/leiningen/lein-pprint/src"),
     :dependencies
     ([org.clojure/tools.nrepl "0.0.5" :exclusions [org.clojure/clojure]]
      [clojure-complete "0.1.4" :exclusions [org.clojure/clojure]]
      [org.thnetos/cd-client "0.3.3" :exclusions [org.clojure/clojure]]),
     :target-path "/home/phil/src/leiningen/lein-pprint/target",
     :name "lein-pprint",
     [...]
     :description "Pretty-print a representation of the project map."}

In order to prevent profile settings from being propagated to other
projects that depend upon yours, the `:default` profiles are removed
from your project when generating the pom, jar, and uberjar, and an
`:uberjar` profile, if present, is included when creating
uberjars. (This can be useful if you want to specify a `:main`
namespace for uberjar use without triggering AOT during regular
development.) Profiles activated through an explicit `with-profile`
invocation will be preserved.