Grails 1.2 comes with a great dependency management. You no longer have to manually manage the dependencies and don’t have to resort to using maven for this task. Grails uses Apache Ivy under the hood for transitive dependency management. Ivy allows to set up multiple resolvers and resolution patterns though allowing you to adapt to maven repositories and many other, even custom repository schemes. Grails takes it a step further and allows you to do this with a pretty nice looking DSL.
Application dependencies are configured in BuildConfig.groovy file and they look something like this…
grails.project.dependency.resolution = {
inherits "global" // inherit Grails' default dependencies
log "warn" // log level of Ivy resolver, either 'error', 'warn', 'info', 'debug' or 'verbose'
repositories {
grailsHome()
mavenCentral()
mavenRepo "http://download.java.net/maven/2/"
mavenRepo "http://repository.jboss.com/maven2/
}
dependencies {
// specify dependencies here under either 'build', 'compile', 'runtime', 'test' or 'provided' scopes eg.
runtime 'com.mysql:mysql-connector-java:5.1.5'
}
}
By default, grails pulls dependencies from your grails installation library. You can also uncomment (as you see above), the mavenCentral() repository. These are the defaults and don’t require any more configuration. You can also specify a custom maven-compatible repo URL using mavenRepo.
There is also a flat dir resolver, allowing you to resolve dependencies to some local directory. You can do this as:
flatDir name: ‘localRepo’, dirs:’/some/path/to/repo’
So I naively tried using flatDir to resolve a local maven repo, which of course didn’t work, since it’s not defined with the maven artifact resolution pattern. In order for that to work, you have to define your own resolver for now. I just submitted a patch to add a mavenLocal() resolver. Should make it to HEAD shortly.
So, for now, you can do
private org.apache.ivy.plugins.resolver.DependencyResolver createLocalMavenResolver() {
def localMavenResolver = new FileSystemResolver();
localMavenResolver.local = true
localMavenResolver.name = "localMavenResolver"
localMavenResolver.m2compatible = true
localMavenResolver.addArtifactPattern "${userHome}/.m2/repository/[organisation]/[module]/[revision]/[artifact]-[revision](-[classifier]).[ext]"
def ivySettings = new IvySettings()
ivySettings.defaultInit()
localMavenResolver.settings = ivySettings
return localMavenResolver
}
Then use this method as…
resolver createLocalMavenResolver()
resolver method basically allows you to specify your own Ivy resolver. But that seems like too much work for something as common as local maven repo, especially since anyone who’s going to use maven dependency artifacts, probably will install some locally.
So once the patch makes it in, you can just uncomment…
mavenLocal()
By default this resolver will resolve dependencies in home_dir/.m2/repository, but you can also specify your own path to the repository by just passing it as an argument…
mavenLocal(“/opt/maven/repository”)
Grails 1.2 is beginning to look very exciting.
Tags: grails, groovy, web development
