1. Library Management

Library Management 

There’s now a getting started page about library management, which you may want to read first.

Documentation Maintenance Note: it would be nice to remove the overlap between this page and the getting started page, leaving this page with the more advanced topics such as checksums and external Ivy files.


There are two ways for you to manage libraries with sbt: manually or automatically. These two ways can be mixed as well. This page discusses the two approaches. All configurations shown here are settings that go directly in a .sbt file.

Manual Dependency Management 

Manually managing dependencies involves copying any jars that you want to use to the lib directory. sbt will put these jars on the classpath during compilation, testing, running, and when using the interpreter. You are responsible for adding, removing, updating, and otherwise managing the jars in this directory. No modifications to your project definition are required to use this method unless you would like to change the location of the directory you store the jars in.

To change the directory jars are stored in, change the unmanagedBase setting in your project definition. For example, to use custom_lib/:

unmanagedBase := baseDirectory.value / "custom_lib"

If you want more control and flexibility, override the unmanagedJars task, which ultimately provides the manual dependencies to sbt. The default implementation is roughly:

Compile / unmanagedJars := (baseDirectory.value ** "*.jar").classpath

If you want to add jars from multiple directories in addition to the default directory, you can do:

Compile / unmanagedJars ++= {
    val base = baseDirectory.value
    val baseDirectories = (base / "libA") +++ (base / "b" / "lib") +++ (base / "libC")
    val customJars = (baseDirectories ** "*.jar") +++ (base / "d" / "my.jar")

See Paths for more information on building up paths.

Automatic Dependency Management 

This method of dependency management involves specifying the direct dependencies of your project and letting sbt handle retrieving and updating your dependencies.

sbt 1.3.0+ uses Coursier to implement dependency management. Until sbt 1.3.0, sbt has used Apache Ivy for ten years. Coursier does a good job of keeping the compatibility, but some of the feature might be specific to Apache Ivy. In those cases, you can use the following setting to switch back to Ivy:

ThisBuild / useCoursier := false

Inline Declarations 

Inline declarations are a basic way of specifying the dependencies to be automatically retrieved. They are intended as a lightweight alternative to a full configuration using Ivy.


Declaring a dependency looks like:

libraryDependencies += groupID % artifactID % revision


libraryDependencies += groupID % artifactID % revision % configuration

See configurations for details on configuration mappings. Also, several dependencies can be declared together:

libraryDependencies ++= Seq(
  groupID %% artifactID % revision,
  groupID %% otherID % otherRevision

If you are using a dependency that was built with sbt, double the first % to be %%:

libraryDependencies += groupID %% artifactID % revision

This will use the right jar for the dependency built with the version of Scala that you are currently using. If you get an error while resolving this kind of dependency, that dependency probably wasn’t published for the version of Scala you are using. See Cross Build for details.

Ivy can select the latest revision of a module according to constraints you specify. Instead of a fixed revision like "1.6.1", you specify "latest.integration", "2.9.+", or "[1.0,)". See the Ivy revisions documentation for details.


sbt uses the standard Maven2 repository by default.

Declare additional repositories with the form:

resolvers += name at location

For example:

libraryDependencies ++= Seq(
    "org.apache.derby" % "derby" % "",
    "org.specs" % "specs" % "1.6.1"

resolvers += "Sonatype OSS Snapshots" at "https://oss.sonatype.org/content/repositories/snapshots"

sbt can search your local Maven repository if you add it as a repository:

resolvers += "Local Maven Repository" at "file://"+Path.userHome.absolutePath+"/.m2/repository"

See Resolvers for details on defining other types of repositories.

Override default resolvers 

resolvers configures additional, inline user resolvers. By default, sbt combines these resolvers with default repositories (Maven Central and the local Ivy repository) to form externalResolvers. To have more control over repositories, set externalResolvers directly. To only specify repositories in addition to the usual defaults, configure resolvers.

For example, to use the Sonatype OSS Snapshots repository in addition to the default repositories,

resolvers += "Sonatype OSS Snapshots" at "https://oss.sonatype.org/content/repositories/snapshots"

To use the local repository, but not the Maven Central repository:

externalResolvers := Resolver.combineDefaultResolvers(resolvers.value.toVector, mavenCentral = false)
Override all resolvers for all builds 

The repositories used to retrieve sbt, Scala, plugins, and application dependencies can be configured globally and declared to override the resolvers configured in a build or plugin definition. There are two parts:

  1. Define the repositories used by the launcher.
  2. Specify that these repositories should override those in build definitions.

The repositories used by the launcher can be overridden by defining ~/.sbt/repositories, which must contain a [repositories] section with the same format as the Launcher configuration file. For example:

my-maven-repo: https://example.org/repo
my-ivy-repo: https://example.org/ivy-repo/, [organization]/[module]/[revision]/[type]s/[artifact](-[classifier]).[ext]

A different location for the repositories file may be specified by the sbt.repository.config system property in the sbt startup script. The final step is to set sbt.override.build.repos to true to use these repositories for dependency resolution and retrieval.

Explicit URL 

If your project requires a dependency that is not present in a repository, a direct URL to its jar can be specified as follows:

libraryDependencies += "slinky" % "slinky" % "2.1" from "https://slinky2.googlecode.com/svn/artifacts/2.1/slinky.jar"

The URL is only used as a fallback if the dependency cannot be found through the configured repositories. Also, the explicit URL is not included in published metadata (that is, the pom or ivy.xml).

Disable Transitivity 

By default, these declarations fetch all project dependencies, transitively. In some instances, you may find that the dependencies listed for a project aren’t necessary for it to build. Projects using the Felix OSGI framework, for instance, only explicitly require its main jar to compile and run. Avoid fetching artifact dependencies with either intransitive() or notTransitive(), as in this example:

libraryDependencies += "org.apache.felix" % "org.apache.felix.framework" % "1.8.0" intransitive()

You can specify the classifier for a dependency using the classifier method. For example, to get the jdk15 version of TestNG:

libraryDependencies += "org.testng" % "testng" % "5.7" classifier "jdk15"

For multiple classifiers, use multiple classifier calls:

libraryDependencies += 
  "org.lwjgl.lwjgl" % "lwjgl-platform" % lwjglVersion classifier "natives-windows" classifier "natives-linux" classifier "natives-osx"

To obtain particular classifiers for all dependencies transitively, run the updateClassifiers task. By default, this resolves all artifacts with the sources or javadoc classifier. Select the classifiers to obtain by configuring the transitiveClassifiers setting. For example, to only retrieve sources:

transitiveClassifiers := Seq("sources")
Exclude Transitive Dependencies 

To exclude certain transitive dependencies of a dependency, use the excludeAll or exclude methods. The exclude method should be used when a pom will be published for the project. It requires the organization and module name to exclude. For example,

libraryDependencies += 
  "log4j" % "log4j" % "1.2.15" exclude("javax.jms", "jms")

The excludeAll method is more flexible, but because it cannot be represented in a pom.xml, it should only be used when a pom doesn’t need to be generated. For example,

libraryDependencies +=
  "log4j" % "log4j" % "1.2.15" excludeAll(
    ExclusionRule(organization = "com.sun.jdmk"),
    ExclusionRule(organization = "com.sun.jmx"),
    ExclusionRule(organization = "javax.jms")

See ModuleID for API details.

In certain cases a transitive dependency should be excluded from all dependencies. This can be achieved by setting up ExclusionRules in excludeDependencies.

excludeDependencies ++= Seq(
  // commons-logging is replaced by jcl-over-slf4j
  ExclusionRule("commons-logging", "commons-logging")
Download Sources 

Downloading source and API documentation jars is usually handled by an IDE plugin. These plugins use the updateClassifiers and updateSbtClassifiers tasks, which produce an Update-Report referencing these jars.

To have sbt download the dependency’s sources without using an IDE plugin, add withSources() to the dependency definition. For API jars, add withJavadoc(). For example:

libraryDependencies += 
  "org.apache.felix" % "org.apache.felix.framework" % "1.8.0" withSources() withJavadoc()

Note that this is not transitive. Use the update*Classifiers tasks for that.

Extra Attributes 

Extra attributes can be specified by passing key/value pairs to the extra method.

To select dependencies by extra attributes:

libraryDependencies += "org" % "name" % "rev" extra("color" -> "blue")

To define extra attributes on the current project:

projectID := {
    val previous = projectID.value
    previous.extra("color" -> "blue", "component" -> "compiler-interface")
Inline Ivy XML 

sbt additionally supports directly specifying the configurations or dependencies sections of an Ivy configuration file inline. You can mix this with inline Scala dependency and repository declarations.

For example:

ivyXML :=
    <dependency org="javax.mail" name="mail" rev="1.4.2">
      <exclude module="activation"/>
Ivy Home Directory 

By default, sbt uses the standard Ivy home directory location ${user.home}/.ivy2/. This can be configured machine-wide, for use by both the sbt launcher and by projects, by setting the system property sbt.ivy.home in the sbt startup script (described in Setup).

For example:

java -Dsbt.ivy.home=/tmp/.ivy2/ ...

sbt (through Ivy) verifies the checksums of downloaded files by default. It also publishes checksums of artifacts by default. The checksums to use are specified by the checksums setting.

To disable checksum checking during update:

update / checksums := Nil

To disable checksum creation during artifact publishing:

publishLocal / checksums := Nil

publish / checksums := Nil

The default value is:

checksums := Seq("sha1", "md5")
Conflict Management 

The conflict manager decides what to do when dependency resolution brings in different versions of the same library. By default, the latest revision is selected. This can be changed by setting conflictManager, which has type ConflictManager. See the Ivy documentation for details on the different conflict managers. For example, to specify that no conflicts are allowed,

conflictManager := ConflictManager.strict

With this set, any conflicts will generate an error. To resolve a conflict, you must configure a dependency override, which is explained in a later section.

Eviction warning 

The following direct dependencies will introduce a conflict on the akka-actor version because banana-rdf requires akka-actor 2.1.4.

libraryDependencies ++= Seq(
  "org.w3" %% "banana-rdf" % "0.4",
  "com.typesafe.akka" %% "akka-actor" % "2.3.7",

The default conflict manager will select the newer version of akka-actor, 2.3.7. This can be confirmed in the output of show update, which shows the newer version as being selected and the older version as evicted.

> show update
[info] compile:

[info]  com.typesafe.akka:akka-actor_2.10
[info]    - 2.3.7
[info]    - 2.1.4
[info]      evicted: true
[info]      evictedReason: latest-revision
[info]      callers: org.w3:banana-rdf_2.10:0.4

Furthermore, the binary version compatibility of the akka-actor 2.1.4 and 2.3.7 are not guaranteed since the second segment has bumped up. sbt 0.13.6+ detects this automatically and prints out the following warning:

[warn] There may be incompatibilities among your library dependencies.
[warn] Here are some of the libraries that were evicted:
[warn]  * com.typesafe.akka:akka-actor_2.10:2.1.4 -> 2.3.7
[warn] Run 'evicted' to see detailed eviction warnings

Since akka-actor 2.1.4 and 2.3.7 are not binary compatible, the only way to fix this is to downgrade your dependency to akka-actor 2.1.4, or upgrade banana-rdf to use akka-actor 2.3.

Overriding a version 

For binary compatible conflicts, sbt provides dependency overrides. They are configured with the dependencyOverrides setting, which is a set of ModuleIDs. For example, the following dependency definitions conflict because spark uses log4j 1.2.16 and scalaxb uses log4j 1.2.17:

libraryDependencies ++= Seq(
   "org.spark-project" %% "spark-core" % "0.5.1",
   "org.scalaxb" %% "scalaxb" % "1.0.0"

The default conflict manager chooses the latest revision of log4j, 1.2.17:

> show update
[info] compile:
[info]    log4j:log4j:1.2.17: ...
[info]    (EVICTED) log4j:log4j:1.2.16

To change the version selected, add an override:

dependencyOverrides += "log4j" % "log4j" % "1.2.16"

This will not add a direct dependency on log4j, but will force the revision to be 1.2.16. This is confirmed by the output of show update:

> show update
[info] compile:
[info]    log4j:log4j:1.2.16

Note: this is an Ivy-only feature and will not be included in a published pom.xml.

Unresolved dependencies error 

Adding the following dependency to your project will result to an unresolved dependencies error of vpp 2.2.1:

libraryDependencies += "org.apache.cayenne.plugins" % "maven-cayenne-plugin" % "3.0.2"

sbt 0.13.6+ will try to reconstruct dependencies tree when it fails to resolve a managed dependency. This is an approximation, but it should help you figure out where the problematic dependency is coming from. When possible sbt will display the source position next to the modules:

[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  ::          UNRESOLVED DEPENDENCIES         ::
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  :: foundrylogic.vpp#vpp;2.2.1: not found
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  Note: Unresolved dependencies path:
[warn]      foundrylogic.vpp:vpp:2.2.1
[warn]        +- org.apache.cayenne:cayenne-tools:3.0.2
[warn]        +- org.apache.cayenne.plugins:maven-cayenne-plugin:3.0.2 (/foo/some-test/build.sbt#L28)
[warn]        +- d:d_2.10:0.1-SNAPSHOT
Cached resolution 

See Cached resolution for performance improvement option.


See Publishing for how to publish your project.


Ivy configurations are a useful feature for your build when you need custom groups of dependencies, such as for a plugin. Ivy configurations are essentially named sets of dependencies. You can read the Ivy documentation for details.

The built-in use of configurations in sbt is similar to scopes in Maven. sbt adds dependencies to different classpaths by the configuration that they are defined in. See the description of Maven Scopes for details.

You put a dependency in a configuration by selecting one or more of its configurations to map to one or more of your project’s configurations. The most common case is to have one of your configurations A use a dependency’s configuration B. The mapping for this looks like "A->B". To apply this mapping to a dependency, add it to the end of your dependency definition:

libraryDependencies += "org.scalatest" %% "scalatest" % "3.2.12" % "test->compile"

This says that your project’s "test" configuration uses ScalaTest’s "compile" configuration. See the Ivy documentation for more advanced mappings. Most projects published to Maven repositories will use the "compile" configuration.

A useful application of configurations is to group dependencies that are not used on normal classpaths. For example, your project might use a "js" configuration to automatically download jQuery and then include it in your jar by modifying resources. For example:

val JS = config("js") hide

ivyConfigurations += JS

libraryDependencies += "jquery" % "jquery" % "3.2.1" % "js->default" from "https://code.jquery.com/jquery-3.2.1.min.js"

Compile / resources ++= update.value.select(configurationFilter("js"))

The config method defines a new configuration with name "js" and makes it private to the project so that it is not used for publishing. See Update Report for more information on selecting managed artifacts.

A configuration without a mapping (no "->") is mapped to "default" or "compile". The -> is only needed when mapping to a different configuration than those. The ScalaTest dependency above can then be shortened to:

libraryDependencies += "org.scalatest" %% "scalatest" % "3.2.12" % "test"
Forcing a revision (Not recommended) 

Note: Forcing can create logical inconsistencies so it’s no longer recommended.

To say that we prefer the version we’ve specified over the version from indirect dependencies, use force():

libraryDependencies ++= Seq(
  "org.spark-project" %% "spark-core" % "0.5.1",
  "log4j" % "log4j" % "1.2.14" force()

Note: this is an Ivy-only feature and cannot be included in a published pom.xml.

Known limitations 

Maven support is dependent on Coursier or Ivy’s support for Maven POMs. Known issues with this support:

  • Specifying relativePath in the parent section of a POM will produce an error.
  • Ivy ignores repositories specified in the POM. A workaround is to specify repositories inline or in an Ivy ivysettings.xml file.