Give slow resolvers a lower priority

sbt-coursier/src/main/scala/coursier/CoursierPlugin.scala

@@ -21,6 +21,7 @@ object CoursierPlugin extends AutoPlugin {
     val coursierVerbosity = Keys.coursierVerbosity
     val mavenProfiles = Keys.mavenProfiles
     val coursierResolvers = Keys.coursierResolvers
+    val coursierReorderResolvers = Keys.coursierReorderResolvers
     val coursierRecursiveResolvers = Keys.coursierRecursiveResolvers
     val coursierSbtResolvers = Keys.coursierSbtResolvers
     val coursierUseSbtCredentials = Keys.coursierUseSbtCredentials
@@ -171,7 +172,8 @@ object CoursierPlugin extends AutoPlugin {
     mavenProfiles := Set.empty,
     coursierUseSbtCredentials := true,
     coursierCredentials := Map.empty,
-    coursierCache := Cache.default
+    coursierCache := Cache.default,
+    coursierReorderResolvers := true
   )
 
   override lazy val projectSettings = coursierSettings(None, Seq(Compile, Test).map(c => c -> c.name)) ++

sbt-coursier/src/main/scala/coursier/Keys.scala

@@ -23,6 +23,10 @@ object Keys {
 
   val mavenProfiles = SettingKey[Set[String]]("maven-profiles")
 
+  val coursierReorderResolvers = SettingKey[Boolean](
+    "coursier-reorder-resolvers",
+    "Whether resolvers should be re-ordered so that typically slow ones are given a lower priority"
+  )
   val coursierResolvers = TaskKey[Seq[Resolver]]("coursier-resolvers")
   val coursierRecursiveResolvers = TaskKey[Seq[Resolver]]("coursier-recursive-resolvers", "Resolvers of the current project, plus those of all from its inter-dependency projects")
   val coursierSbtResolvers = TaskKey[Seq[Resolver]]("coursier-sbt-resolvers")

sbt-coursier/src/main/scala/coursier/Tasks.scala

@@ -44,15 +44,44 @@ object Tasks {
     structure(state).allProjectRefs.filter(p => deps(p.project))
   }
 
+  private val slowReposBase = Seq(
+    "https://repo.typesafe.com/",
+    "https://repo.scala-sbt.org/",
+    "http://repo.typesafe.com/",
+    "http://repo.scala-sbt.org/"
+  )
+
+  private val fastReposBase = Seq(
+    "http://repo1.maven.org/",
+    "https://repo1.maven.org/"
+  )
+
   def coursierResolversTask: Def.Initialize[sbt.Task[Seq[Resolver]]] = Def.task {
 
+    def url(res: Resolver): Option[String] =
+      res match {
+        case m: SbtCompatibility.MavenRepository =>
+          Some(m.root)
+        case u: sbt.URLRepository =>
+          u.patterns.artifactPatterns.headOption
+            .orElse(u.patterns.ivyPatterns.headOption)
+        case _ =>
+          None
+      }
+
+    def fastRepo(res: Resolver): Boolean =
+      url(res).exists(u => fastReposBase.exists(u.startsWith))
+    def slowRepo(res: Resolver): Boolean =
+      url(res).exists(u => slowReposBase.exists(u.startsWith))
+
     val extRes = externalResolvers.value
     val isSbtPlugin = sbtPlugin.value
     val sbtRes = sbtResolver.value
     val bootResOpt = bootResolvers.value
     val overrideFlag = overrideBuildResolvers.value
+    val reorderResolvers = coursierReorderResolvers.value
 
-    bootResOpt.filter(_ => overrideFlag).getOrElse {
+    val result = bootResOpt.filter(_ => overrideFlag).getOrElse {
       var resolvers = extRes
       if (isSbtPlugin)
         resolvers = Seq(
@@ -61,6 +90,12 @@ object Tasks {
         ) ++ resolvers
       resolvers
     }
+
+    if (reorderResolvers && result.exists(fastRepo) && result.exists(slowRepo)) {
+      val (slow, other) = result.partition(slowRepo)
+      other ++ slow
+    } else
+      result
   }
 
   def coursierRecursiveResolversTask: Def.Initialize[sbt.Task[Seq[Resolver]]] =