Support Coursier plugins via customizing FileCache used (with classloaders)

main/src/mill/modules/Jvm.scala

@@ -534,6 +534,7 @@ object Jvm {
       sources: Boolean = false,
       mapDependencies: Option[Dependency => Dependency] = None,
       customizer: Option[coursier.core.Resolution => coursier.core.Resolution] = None,
+      cacheCustomizer: Option[coursier.cache.FileCache[Task] => coursier.cache.FileCache[Task]] = None,
       ctx: Option[mill.api.Ctx.Log] = None
   ): Result[Agg[PathRef]] = {
 
@@ -543,6 +544,7 @@ object Jvm {
       force,
       mapDependencies,
       customizer,
+      cacheCustomizer,
       ctx
     )
     val errs = resolution.errors
@@ -561,12 +563,15 @@ object Jvm {
       Result.Failure(msg)
     } else {
 
+      val cache0 = coursier.cache.FileCache[Task].noCredentials
+      val cache = cacheCustomizer.getOrElse(identity[coursier.cache.FileCache[Task]](_)).apply(cache0)
+
       def load(artifacts: Seq[coursier.util.Artifact]) = {
 
         import scala.concurrent.ExecutionContext.Implicits.global
         val loadedArtifacts = Gather[Task].gather(
           for (a <- artifacts)
-            yield coursier.cache.Cache.default.file(a).run.map(a.optional -> _)
+            yield cache.file(a).run.map(a.optional -> _)
         ).unsafeRun
 
         val errors = loadedArtifacts.collect {
@@ -611,6 +616,7 @@ object Jvm {
       force: IterableOnce[coursier.Dependency],
       mapDependencies: Option[Dependency => Dependency] = None,
       customizer: Option[coursier.core.Resolution => coursier.core.Resolution] = None,
+      cacheCustomizer: Option[coursier.cache.FileCache[Task] => coursier.cache.FileCache[Task]] = None,
       ctx: Option[mill.api.Ctx.Log] = None
   ): (Seq[Dependency], Resolution) = {
 
@@ -631,13 +637,14 @@ object Jvm {
     val start = customizer.getOrElse(identity[Resolution](_)).apply(start0)
 
     val resolutionLogger = ctx.map(c => new TickerResolutionLogger(c))
-    val cache = resolutionLogger match {
+    val cache0 = resolutionLogger match {
       case None => coursier.cache.FileCache[Task].withCachePolicies(cachePolicies)
       case Some(l) =>
         coursier.cache.FileCache[Task]
           .withCachePolicies(cachePolicies)
           .withLogger(l)
     }
+    val cache = cacheCustomizer.getOrElse(identity[coursier.cache.FileCache[Task]](_)).apply(cache0)
 
     val fetches = cache.fetchs
 
@@ -781,6 +788,7 @@ object Jvm {
       sources = sources,
       mapDependencies = mapDependencies,
       customizer = None,
+      cacheCustomizer = None,
       ctx = ctx
     )
 
@@ -801,6 +809,7 @@ object Jvm {
       force = force,
       mapDependencies = mapDependencies,
       customizer = None,
+      cacheCustomizer = None,
       ctx = ctx
     )
 

scalalib/src/CoursierModule.scala

@@ -1,7 +1,8 @@
 package mill.scalalib
 
-import scala.annotation.nowarn
+import coursier.cache.FileCache
 
+import scala.annotation.nowarn
 import coursier.{Dependency, Repository, Resolve}
 import coursier.core.Resolution
 import mill.{Agg, T}
@@ -35,6 +36,7 @@ trait CoursierModule extends mill.Module {
       sources = sources,
       mapDependencies = Some(mapDependencies()),
       customizer = resolutionCustomizer(),
+      cacheCustomizer = cacheCustomizer(),
       ctx = Some(implicitly[mill.api.Ctx.Log])
     )
   }
@@ -71,6 +73,22 @@ trait CoursierModule extends mill.Module {
    */
   def resolutionCustomizer: Task[Option[Resolution => Resolution]] = T.task { None }
 
+  /**
+   * Customize the coursier file cache.
+   *
+   * This is rarely needed to be changed, but sometimes e.g you want to load a coursier plugin.
+   * Doing so requires adding to coursier's classpath. To do this you could use the following:
+   * {{{
+   *   override def cacheCustomizer = T.task {
+   *      Some( (fc: coursier.cache.FileCache[Task]) =>
+   *        fc.withClassLoaders(Seq(classOf[coursier.cache.protocol.S3Handler].getClassLoader))
+   *      )
+   *   }
+   * }}}
+   * @return
+   */
+  def cacheCustomizer: Task[Option[FileCache[coursier.util.Task] => FileCache[coursier.util.Task]]] = T.task { None }
+
   /**
    * The repositories used to resolved dependencies with [[resolveDeps()]].
    */

scalalib/src/JavaModule.scala

@@ -536,7 +536,8 @@ trait JavaModule
         resolveCoursierDependency().apply(_),
         additionalDeps() ++ transitiveIvyDeps(),
         Some(mapDependencies()),
-        customizer = resolutionCustomizer()
+        customizer = resolutionCustomizer(),
+        cacheCustomizer = cacheCustomizer(),
       )
 
       println(

scalalib/src/Lib.scala

@@ -6,6 +6,7 @@ import java.lang.annotation.Annotation
 import java.lang.reflect.Modifier
 import java.util.zip.ZipInputStream
 
+import coursier.util.Task
 import coursier.{Dependency, Fetch, Repository, Resolution}
 import mill.api.{Ctx, Loose, PathRef, Result}
 import sbt.testing._
@@ -29,6 +30,7 @@ object Lib {
       deps: IterableOnce[Dep],
       mapDependencies: Option[Dependency => Dependency] = None,
       customizer: Option[coursier.core.Resolution => coursier.core.Resolution] = None,
+      cacheCustomizer: Option[coursier.cache.FileCache[Task] => coursier.cache.FileCache[Task]] = None,
       ctx: Option[Ctx.Log] = None
   ): (Seq[Dependency], Resolution) = {
     val depSeq = deps.iterator.toSeq
@@ -38,6 +40,7 @@ object Lib {
       force = depSeq.filter(_.force).map(depToDependency),
       mapDependencies = mapDependencies,
       customizer = customizer,
+      cacheCustomizer = cacheCustomizer,
       ctx = ctx
     )
   }
@@ -56,6 +59,7 @@ object Lib {
       sources: Boolean = false,
       mapDependencies: Option[Dependency => Dependency] = None,
       customizer: Option[coursier.core.Resolution => coursier.core.Resolution] = None,
+      cacheCustomizer: Option[coursier.cache.FileCache[Task] => coursier.cache.FileCache[Task]] = None,
       ctx: Option[Ctx.Log] = None
   ): Result[Agg[PathRef]] = {
     val depSeq = deps.iterator.toSeq
@@ -66,6 +70,7 @@ object Lib {
       sources = sources,
       mapDependencies = mapDependencies,
       customizer = customizer,
+      cacheCustomizer = cacheCustomizer,
       ctx = ctx
     )
   }
@@ -137,6 +142,7 @@ object Lib {
       deps = deps,
       mapDependencies = mapDependencies,
       customizer = None,
+      cacheCustomizer = None,
       ctx = ctx
     )
 
@@ -159,6 +165,7 @@ object Lib {
       sources = sources,
       mapDependencies = mapDependencies,
       customizer = None,
+      cacheCustomizer = None,
       ctx = ctx
     )
 

scalalib/src/dependency/versions/VersionsFinder.scala

@@ -39,6 +39,7 @@ private[dependency] object VersionsFinder {
         val repos = javaModule.repositoriesTask()
         val mapDeps = javaModule.mapDependencies()
         val custom = javaModule.resolutionCustomizer()
+        val cacheCustom = javaModule.cacheCustomizer()
 
         val (dependencies, _) =
           Lib.resolveDependenciesMetadata(
@@ -47,6 +48,7 @@ private[dependency] object VersionsFinder {
             deps = deps ++ compileIvyDeps ++ runIvyDeps,
             mapDependencies = Some(mapDeps),
             customizer = custom,
+            cacheCustomizer = cacheCustom,
             ctx = Some(T.log)
           )