diff --git a/base-plugin/src/integTest/groovy/com/github/jrubygradle/JRubyPrepareGemsIntegrationSpec.groovy b/base-plugin/src/integTest/groovy/com/github/jrubygradle/JRubyPrepareGemsIntegrationSpec.groovy
index 00618560..87218748 100644
--- a/base-plugin/src/integTest/groovy/com/github/jrubygradle/JRubyPrepareGemsIntegrationSpec.groovy
+++ b/base-plugin/src/integTest/groovy/com/github/jrubygradle/JRubyPrepareGemsIntegrationSpec.groovy
@@ -30,8 +30,9 @@ import spock.lang.Issue
 
 /**
  * @author Schalk W. Cronjé.
+ * @author Guillaume Grossetie
  */
-@IgnoreIf({System.getProperty('TESTS_ARE_OFFLINE')})
+@IgnoreIf({ IntegrationSpecification.OFFLINE })
 class JRubyPrepareGemsIntegrationSpec extends IntegrationSpecification {
 
     static final String DEFAULT_TASK_NAME = 'jrubyPrepare'
@@ -54,7 +55,6 @@ class JRubyPrepareGemsIntegrationSpec extends IntegrationSpecification {
         new File(projectDir, "gems/slim-${slimVersion}").exists()
     }
 
-    @IgnoreIf({ IntegrationSpecification.OFFLINE })
     void "Check if rack version gets resolved"() {
         setup:
         withPreamble """repositories.ruby.gems()
@@ -76,7 +76,6 @@ class JRubyPrepareGemsIntegrationSpec extends IntegrationSpecification {
         new File(projectDir, "gems/rack-1.6.12").exists()
     }
 
-    @IgnoreIf({ IntegrationSpecification.OFFLINE })
     void "Check if selenium-webdriver version gets resolved"() {
         setup:
         withPreamble """repositories.ruby.gems()
@@ -97,7 +96,6 @@ class JRubyPrepareGemsIntegrationSpec extends IntegrationSpecification {
         new File(projectDir, "gems/selenium-webdriver-3.142.6").exists()
     }
 
-    @IgnoreIf({ IntegrationSpecification.OFFLINE })
     void "Check that GEM dependencies are locked"() {
         setup:
         File lockFile = new File(projectDir, 'gradle/dependency-locks/gems.lockfile')
@@ -139,7 +137,6 @@ rubygems:tilt:2.0.9
         new File(projectDir, "gems/rack-1.6.10").exists()
     }
 
-    @IgnoreIf({ IntegrationSpecification.OFFLINE })
     void "Check if prerelease gem gets resolved"() {
         setup:
         withDefaultRepositories()
@@ -156,7 +153,6 @@ rubygems:tilt:2.0.9
     }
 
     @Issue('https://github.com/jruby-gradle/jruby-gradle-plugin/issues/341')
-    @IgnoreIf({ IntegrationSpecification.OFFLINE })
     void "Make an install-time gem dependency available"() {
         setup:
         withRubyGemsRepository()
diff --git a/base-plugin/src/main/groovy/com/github/jrubygradle/JRubyExec.groovy b/base-plugin/src/main/groovy/com/github/jrubygradle/JRubyExec.groovy
index a213c38b..c47c39b9 100644
--- a/base-plugin/src/main/groovy/com/github/jrubygradle/JRubyExec.groovy
+++ b/base-plugin/src/main/groovy/com/github/jrubygradle/JRubyExec.groovy
@@ -26,6 +26,7 @@ package com.github.jrubygradle
 import com.github.jrubygradle.api.core.JRubyAwareTask
 import com.github.jrubygradle.api.core.JRubyExecSpec
 import com.github.jrubygradle.internal.JRubyExecUtils
+import groovy.transform.CompileStatic
 import org.gradle.api.Task
 import org.gradle.api.artifacts.Configuration
 import org.gradle.api.provider.Provider
@@ -48,6 +49,7 @@ import static org.ysb33r.grolifant.api.StringUtils.stringize
  * @author Christian Meier
  *
  */
+@CompileStatic
 class JRubyExec extends JavaExec implements JRubyAwareTask, JRubyExecSpec {
 
     public static final String MAIN_CLASS = 'org.jruby.Main'
@@ -65,13 +67,13 @@ class JRubyExec extends JavaExec implements JRubyAwareTask, JRubyExecSpec {
         super.setMain MAIN_CLASS
         this.jruby = extensions.create(JRubyPluginExtension.NAME, JRubyPluginExtension, this)
 
-        inputs.property 'jrubyver', {
+        inputs.property 'jrubyver', { JRubyPluginExtension jruby ->
             jruby.jrubyVersion
-        }
+        }.curry(this.jruby)
 
-        inputs.property 'gemConfiguration', {
+        inputs.property 'gemConfiguration', { JRubyPluginExtension jruby ->
             jruby.gemConfiguration
-        }
+        }.curry(this.jruby)
 
         if (GradleVersion.current() >= GradleVersion.version('4.10')) {
             dependsOn(project.provider({ JRubyPluginExtension jpe ->
@@ -85,7 +87,7 @@ class JRubyExec extends JavaExec implements JRubyAwareTask, JRubyExecSpec {
     }
 
     /** Script to execute.
-     * @return The path to the script (or nul if not set)
+     * @return The path to the script (or {@code null} if not set)
      */
     @Optional
     @Input
@@ -184,12 +186,12 @@ class JRubyExec extends JavaExec implements JRubyAwareTask, JRubyExecSpec {
     /** If it is required that a JRubyExec task needs to be executed with a different version of JRuby that the
      * globally configured one, it can be done by setting it here.
      *
-     * @deprecated Use{@code jruby.getProposedJRubyVersion( )} instead.
+     * @deprecated Use {@code jruby.getJrubyVersion( )} instead.
      *
      */
     @Deprecated
     String getJrubyVersion() {
-        deprecated('Use jruby.getProposedJRubyVersion() rather getProposedJRubyVersion()')
+        deprecated('Use jruby.getJrubyVersion() rather getJrubyVersion()')
         jruby.jrubyVersion
     }
 
diff --git a/base-plugin/src/main/groovy/com/github/jrubygradle/JRubyPluginExtension.groovy b/base-plugin/src/main/groovy/com/github/jrubygradle/JRubyPluginExtension.groovy
index e5104843..7d4605ec 100644
--- a/base-plugin/src/main/groovy/com/github/jrubygradle/JRubyPluginExtension.groovy
+++ b/base-plugin/src/main/groovy/com/github/jrubygradle/JRubyPluginExtension.groovy
@@ -111,7 +111,7 @@ class JRubyPluginExtension extends AbstractCombinedProjectTaskExtension {
      */
     @Deprecated
     String getDefaultVersion() {
-        deprecated('Use getProposedJRubyVersion() rather than getDefaultVersion()')
+        deprecated('Use getJrubyVersion() rather than getDefaultVersion()')
         getJrubyVersion()
     }
 
diff --git a/base-plugin/src/test/groovy/com/github/jrubygradle/JRubyExecTaskSpec.groovy b/base-plugin/src/test/groovy/com/github/jrubygradle/JRubyExecTaskSpec.groovy
index ea761972..720adb96 100644
--- a/base-plugin/src/test/groovy/com/github/jrubygradle/JRubyExecTaskSpec.groovy
+++ b/base-plugin/src/test/groovy/com/github/jrubygradle/JRubyExecTaskSpec.groovy
@@ -72,12 +72,12 @@ class JRubyExecTaskSpec extends Specification {
         when:
         project.configure(execTask) {
             jruby.gemConfiguration configurationName
-            jruby.getProposedJRubyVersion newVersion
+            jruby.jrubyVersion newVersion
         }
         project.evaluate()
 
         then:
-        execTask.jruby.jrubyVersion != project.jruby.getProposedJRubyVersion
+        execTask.jruby.jrubyVersion != project.jruby.jrubyVersion
 
         and: "jrubyConfigurationName must point to this new configuration"
         execTask.jruby.getGemConfiguration().name == configurationName
diff --git a/core-plugin/src/integTest/groovy/com/github/jrubygradle/api/core/IvyXmlProxyServerIntegrationSpec.groovy b/core-plugin/src/integTest/groovy/com/github/jrubygradle/api/core/IvyXmlProxyServerIntegrationSpec.groovy
index e606ceae..00a4c66c 100644
--- a/core-plugin/src/integTest/groovy/com/github/jrubygradle/api/core/IvyXmlProxyServerIntegrationSpec.groovy
+++ b/core-plugin/src/integTest/groovy/com/github/jrubygradle/api/core/IvyXmlProxyServerIntegrationSpec.groovy
@@ -30,6 +30,7 @@ import org.junit.rules.TemporaryFolder
 import spock.lang.IgnoreIf
 import spock.lang.Issue
 import spock.lang.Specification
+import spock.lang.Unroll
 
 import java.util.regex.Pattern
 
@@ -185,7 +186,7 @@ class IvyXmlProxyServerIntegrationSpec extends Specification {
         build()
 
         then:
-        findFiles (~/^asciidoctor-pdf.*\.gem$/).size() == 3
+        findFiles(~/^asciidoctor-pdf.*\.gem$/).size() == 3
     }
 
     @Issue('https://github.com/jruby-gradle/jruby-gradle-plugin/issues/380')
@@ -243,14 +244,16 @@ class IvyXmlProxyServerIntegrationSpec extends Specification {
             .build()
     }
 
-    private void withBuildFile(String content) {
+    private void withBuildFile(String content, boolean prerelease = false) {
         buildFile.text = """
         plugins {
             id 'com.github.jruby-gradle.core'
         }
 
         repositories {
-            ruby.gems()
+            ruby.gems {
+                prerelease = ${prerelease}
+            }
         }
 
         configurations {
diff --git a/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/GemRepositoryConfiguration.groovy b/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/GemRepositoryConfiguration.groovy
new file mode 100644
index 00000000..548662bd
--- /dev/null
+++ b/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/GemRepositoryConfiguration.groovy
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2014-2019, R. Tyler Croy <rtyler@brokenco.de>,
+ *     Schalk Cronje <ysb33r@gmail.com>, Christian Meier, Lookout, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.github.jrubygradle.api.core
+
+import groovy.transform.CompileStatic
+
+/** Additional options for configuring a remote GEM repository
+ *
+ * @author Schalk W. Cronjé
+ *
+ * @since 2.0
+ */
+@CompileStatic
+class GemRepositoryConfiguration {
+
+    /** Set whether pre-release GEMs should be considered.
+     *
+     */
+    boolean prerelease = false
+}
diff --git a/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/RepositoryHandlerExtension.groovy b/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/RepositoryHandlerExtension.groovy
index dfb4ff00..a24e48d9 100644
--- a/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/RepositoryHandlerExtension.groovy
+++ b/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/RepositoryHandlerExtension.groovy
@@ -31,8 +31,8 @@ import org.gradle.api.Action
 import org.gradle.api.Project
 import org.gradle.api.artifacts.repositories.ArtifactRepository
 import org.gradle.api.artifacts.repositories.IvyArtifactRepository
-import org.gradle.api.artifacts.repositories.MavenArtifactRepository
 import org.gradle.util.GradleVersion
+import org.ysb33r.grolifant.api.ClosureUtils
 
 /** Extension which can be added to {@code project.repositories}.
  *
@@ -60,7 +60,31 @@ class RepositoryHandlerExtension {
      * @return Artifact repository.
      */
     ArtifactRepository gems() {
-        bindRepositoryToProxyServer('https://rubygems.org'.toURI(), DEFAULT_GROUP_NAME)
+        bindRepositoryToProxyServer(
+            RUBYGEMS_URI,
+            DEFAULT_GROUP_NAME,
+            new GemRepositoryConfiguration()
+        )
+    }
+
+    /** Create an artifact repository which will use {@link https://rubygems.org} and
+     * associate group {@code rubygems} with it.
+     *
+     * @param cfg GEM repository configuration
+     * @return Artifact repository.
+     */
+    ArtifactRepository gems(@DelegatesTo(GemRepositoryConfiguration) Closure cfg) {
+        bindRepositoryToProxyServer(RUBYGEMS_URI, DEFAULT_GROUP_NAME, cfg)
+    }
+
+    /** Create an artifact repository which will use {@link https://rubygems.org} and
+     * associate group {@code rubygems} with it.
+     *
+     * @param cfg GEM repository configuration
+     * @return Artifact repository.
+     */
+    ArtifactRepository gems(Action<GemRepositoryConfiguration> cfg) {
+        bindRepositoryToProxyServer(RUBYGEMS_URI, DEFAULT_GROUP_NAME, cfg)
     }
 
     /** Create an artifact repository which will use specified URI and
@@ -72,7 +96,33 @@ class RepositoryHandlerExtension {
      * @return Artifact repository.
      */
     ArtifactRepository gems(Object uri) {
-        bindRepositoryToProxyServer(project.uri(uri), DEFAULT_GROUP_NAME)
+        bindRepositoryToProxyServer(project.uri(uri), DEFAULT_GROUP_NAME, new GemRepositoryConfiguration())
+    }
+
+    /** Create an artifact repository which will use specified URI and
+     * associate group {@code rubygems} with it.
+     *
+     * @param uri URI of remote repository that serves up Rubygems. Any object convertible
+     * with {@code project.uri} can be provided.
+     * @param cfg GEM repository configuration
+     *
+     * @return Artifact repository.
+     */
+    ArtifactRepository gems(Object uri, @DelegatesTo(GemRepositoryConfiguration) Closure cfg) {
+        bindRepositoryToProxyServer(project.uri(uri), DEFAULT_GROUP_NAME, cfg)
+    }
+
+    /** Create an artifact repository which will use specified URI and
+     * associate group {@code rubygems} with it.
+     *
+     * @param uri URI of remote repository that serves up Rubygems. Any object convertible
+     * with {@code project.uri} can be provided.
+     * @param cfg GEM repository configuration
+     *
+     * @return Artifact repository.
+     */
+    ArtifactRepository gems(Object uri, Action<GemRepositoryConfiguration> cfg) {
+        bindRepositoryToProxyServer(project.uri(uri), DEFAULT_GROUP_NAME, cfg)
     }
 
     /** Create an artifact repository which will use specified URI and
@@ -84,37 +134,65 @@ class RepositoryHandlerExtension {
      * @return Artifact repository.
      */
     ArtifactRepository gems(String group, Object uri) {
-        bindRepositoryToProxyServer(project.uri(uri), group)
+        bindRepositoryToProxyServer(project.uri(uri), group, new GemRepositoryConfiguration())
     }
 
-    /** Adds the legacy Torquebox Maven proxy to {@code rubygems.org}.
+    /** Create an artifact repository which will use specified URI and
+     * associate a specified group with it.
      *
-     * Please note that this proxy is effectively unmaintained an no longer supported
-     * by the original creators.
+     * @param group Group to associate this server with.
+     * @param uri URI of remote repository that serves up Rubygems. Any object convertible
+     * with {@code project.uri} can be provided.
+     * @param cfg GEM repository configuration
+     * @return Artifact repository.
+     */
+    ArtifactRepository gems(String group, Object uri, @DelegatesTo(GemRepositoryConfiguration) Closure cfg) {
+        bindRepositoryToProxyServer(project.uri(uri), group, cfg)
+    }
+
+    /** Create an artifact repository which will use specified URI and
+     * associate a specified group with it.
      *
-     * @return Maven artifact repository
+     * @param group Group to associate this server with.
+     * @param uri URI of remote repository that serves up Rubygems. Any object convertible
+     * with {@code project.uri} can be provided.
+     * @param cfg GEM repository configuration
+     * @return Artifact repository.
      */
-    MavenArtifactRepository torquebox() {
-        Action mvnConfigurator = new Action<MavenArtifactRepository>() {
-            void execute(MavenArtifactRepository mvn) {
-                mvn.url = 'http://rubygems-proxy.torquebox.org/releases'.toURI()
-            }
-        }
-        (MavenArtifactRepository) restrictToGems(
-            this.project.repositories.maven(mvnConfigurator),
-            DEFAULT_GROUP_NAME
-        )
+    ArtifactRepository gems(String group, Object uri, Action<GemRepositoryConfiguration> cfg) {
+        bindRepositoryToProxyServer(project.uri(uri), group, cfg)
     }
 
     private ArtifactRepository bindRepositoryToProxyServer(
         URI serverUri,
-        String group
+        String group,
+        GemRepositoryConfiguration cfg
     ) {
-        IvyXmlProxyServer proxy = ivyProxies.registerProxy(serverUri, group)
+        IvyXmlProxyServer proxy = ivyProxies.registerProxy(serverUri, group, cfg)
         project.extensions.getByType(GemResolverStrategy).addGemGroup(group)
         restrictToGems(createIvyRepo(serverUri, proxy.bindAddress), group)
     }
 
+    private ArtifactRepository bindRepositoryToProxyServer(
+        URI serverUri,
+        String group,
+        @DelegatesTo(GemRepositoryConfiguration) Closure cfg
+    ) {
+        GemRepositoryConfiguration grc = new GemRepositoryConfiguration()
+        ClosureUtils.configureItem(grc, cfg)
+        bindRepositoryToProxyServer(serverUri, group, grc)
+    }
+
+    private ArtifactRepository bindRepositoryToProxyServer(
+        URI serverUri,
+        String group,
+        Action<GemRepositoryConfiguration> cfg
+    ) {
+        GemRepositoryConfiguration grc = new GemRepositoryConfiguration()
+        cfg.execute(grc)
+        bindRepositoryToProxyServer(serverUri, group, grc)
+    }
+
     @CompileDynamic
     private IvyArtifactRepository createIvyRepo(URI server, URI bindAddress) {
         this.project.repositories.ivy {
@@ -141,4 +219,5 @@ class RepositoryHandlerExtension {
     private final IvyXmlGlobalProxyRegistry ivyProxies
     private static final boolean HAS_CONTENT_FEATURE = GradleVersion.current() >= GradleVersion.version('5.1')
     private static final boolean HAS_SECURE_PROTOCOL_FEATURE = GradleVersion.current() >= GradleVersion.version('6.0')
+    private static final URI RUBYGEMS_URI = 'https://rubygems.org'.toURI()
 }
diff --git a/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/RubyGemQueryRestApi.java b/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/RubyGemQueryRestApi.java
index 0ba83bd9..73cf0046 100644
--- a/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/RubyGemQueryRestApi.java
+++ b/core-plugin/src/main/groovy/com/github/jrubygradle/api/core/RubyGemQueryRestApi.java
@@ -33,9 +33,10 @@
  *
  * @since 2.0.
  *
- * @see https://guides.rubygems.org/rubygems-org-api
+ * @see {@link https://guides.rubygems.org/rubygems-org-api}
  */
 public interface RubyGemQueryRestApi {
+
     /**
      * Return all published versions for a specific GEM
      *
@@ -45,6 +46,16 @@ public interface RubyGemQueryRestApi {
      */
     List<String> allVersions(String gemName) throws ApiException;
 
+    /**
+     * Return all published versions for a specific GEM
+     *
+     * @param gemName Name of GEM.
+     * @param includePrelease Whether pre-release versions should be included.
+     * @return List of versions. Can be empty if the GEM does not have any versions. Never {@code null}.
+     * @throws {@link ApiException} if a networking or parser error occurs.
+     */
+    List<String> allVersions(String gemName, boolean includePrelease) throws ApiException;
+
     /**
      * Return latest published version of GEM.
      *
@@ -54,6 +65,16 @@ public interface RubyGemQueryRestApi {
      */
     String latestVersion(String gemName) throws ApiException;
 
+    /**
+     * Return latest published version of GEM.
+     *
+     * @param gemName Name of GEM.
+     * @param allowPrerelease Whether a prereleased version can be considered a latest version.
+     * @return Version of GEM
+     * @throws {@link ApiException} if GEM does not exist.
+     */
+    String latestVersion(String gemName, boolean allowPrerelease) throws ApiException;
+
     /** Returns the basic metadata for a GEM.
      *
      * @param gemName Name of GEM.
diff --git a/core-plugin/src/main/groovy/com/github/jrubygradle/api/gems/GemVersion.groovy b/core-plugin/src/main/groovy/com/github/jrubygradle/api/gems/GemVersion.groovy
index 286476f9..15ee9329 100644
--- a/core-plugin/src/main/groovy/com/github/jrubygradle/api/gems/GemVersion.groovy
+++ b/core-plugin/src/main/groovy/com/github/jrubygradle/api/gems/GemVersion.groovy
@@ -62,6 +62,7 @@ import static com.github.jrubygradle.api.gems.GemVersion.Boundary.OPEN_ENDED
  *
  * @author Christian Meier
  * @author Schalk W. Cronjé
+ * @author Guillaume Grossetie
  *
  * @since 2.0 (Moved here from base plugin where it existed since 0.4.0)
  */
diff --git a/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/AbstractIvyXmlProxyServer.groovy b/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/AbstractIvyXmlProxyServer.groovy
index d25746c7..94d9496b 100644
--- a/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/AbstractIvyXmlProxyServer.groovy
+++ b/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/AbstractIvyXmlProxyServer.groovy
@@ -24,6 +24,7 @@
 package com.github.jrubygradle.internal.core
 
 import com.github.jrubygradle.api.core.ApiException
+import com.github.jrubygradle.api.core.GemRepositoryConfiguration
 import com.github.jrubygradle.api.core.IvyXmlProxyServer
 import com.github.jrubygradle.api.core.RubyGemQueryRestApi
 import com.github.jrubygradle.api.gems.GemInfo
@@ -94,12 +95,19 @@ abstract class AbstractIvyXmlProxyServer implements IvyXmlProxyServer {
      * @param cache Root directory for local Ivy XML cache.
      * @param serverUri URI of remote Rubygems proxy.
      * @param group Group that will be associated with the Rubygems proxy.
+     * @param grc       Additional configuration regarding remote GEM server
      */
-    protected AbstractIvyXmlProxyServer(File cache, URI serverUri, String group) {
+    protected AbstractIvyXmlProxyServer(
+        File cache,
+        URI serverUri,
+        String group,
+        GemRepositoryConfiguration grc
+    ) {
         localCachePath = cache
         gemToIvy = new GemToIvy(serverUri)
         api = new DefaultRubyGemRestApi(serverUri)
         this.group = group
+        this.configuration = grc
     }
 
     @Synchronized
@@ -170,7 +178,7 @@ abstract class AbstractIvyXmlProxyServer implements IvyXmlProxyServer {
     protected String getDirectoryListing(String grp, String name) throws NotFound {
         if (inGroups(grp)) {
             debug "Request to find all versions for ${grp}:${name}"
-            List<String> versions = api.allVersions(name)
+            List<String> versions = api.allVersions(name, configuration.prerelease)
             debug "Got versions ${versions.join(', ')}"
             revisionsAsHtmlDirectoryListing(versions)
         } else {
@@ -185,7 +193,7 @@ abstract class AbstractIvyXmlProxyServer implements IvyXmlProxyServer {
 
     private String getGemQueryRevisionFromIvy(String gemName, String revisionPattern) {
         GemVersion version = gemVersionFromGradleIvyRequirement(revisionPattern)
-        version.highOpenEnded ? api.latestVersion(gemName) : version.high
+        version.highOpenEnded ? api.latestVersion(gemName, configuration.prerelease) : version.high
     }
 
     private void debug(String text) {
@@ -203,4 +211,5 @@ abstract class AbstractIvyXmlProxyServer implements IvyXmlProxyServer {
     private final GemToIvy gemToIvy
     private final RubyGemQueryRestApi api
     private final String group
+    private final GemRepositoryConfiguration configuration
 }
diff --git a/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/DefaultRubyGemRestApi.groovy b/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/DefaultRubyGemRestApi.groovy
index f1af2eb1..e0ac5817 100644
--- a/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/DefaultRubyGemRestApi.groovy
+++ b/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/DefaultRubyGemRestApi.groovy
@@ -23,6 +23,7 @@
  */
 package com.github.jrubygradle.internal.core
 
+import com.github.jrubygradle.api.core.ApiException
 import com.github.jrubygradle.api.gems.GemInfo
 import com.github.jrubygradle.api.gems.JarDependency
 import com.github.jrubygradle.internal.gems.DefaultGemDependency
@@ -33,6 +34,7 @@ import groovy.transform.CompileStatic
 import groovyx.net.http.HttpBuilder
 import groovyx.net.http.HttpException
 import okhttp3.OkHttpClient
+import org.gradle.util.GradleVersion
 
 import static com.github.jrubygradle.internal.gems.GemToIvy.JAVA_PLATFORM
 import static groovyx.net.http.ContentTypes.JSON
@@ -51,7 +53,7 @@ class DefaultRubyGemRestApi implements com.github.jrubygradle.api.core.RubyGemQu
 
     /** Creates a client from a URI
      *
-     * @param serverUri URI as a String. ONly the scheme plus host
+     * @param serverUri URI as a String. Only the scheme plus host
      * parts should be provided.
      */
     DefaultRubyGemRestApi(final String serverUri) {
@@ -74,12 +76,25 @@ class DefaultRubyGemRestApi implements com.github.jrubygradle.api.core.RubyGemQu
      * @throw {@link com.github.jrubygradle.api.core.ApiException} if a networking error occurred.
      */
     @Override
-    @SuppressWarnings('CatchThrowable')
     List<String> allVersions(String gemName) {
+        allVersions(gemName, false)
+    }
+
+    /**
+     * Return all published versions for a specific GEM
+     *
+     * @param gemName Name of GEM.
+     * @param includePrelease Whether pre-release versions should be included.
+     * @return List of versions. Can be empty if the GEM does not have any versions. Never {@code null}.
+     * @throws {@link ApiException} if a networking or parser error occurs.
+     */
+    @Override
+    @SuppressWarnings('CatchThrowable')
+    List<String> allVersions(String gemName, boolean includePrelease) {
         try {
-            extractVersions(getData(V1, "versions/${gemName}"))
+            extractVersions(getData(V1, "versions/${gemName}"), includePrelease)
         } catch (Throwable e) {
-            throw new com.github.jrubygradle.api.core.ApiException("Count not retrieve list of versions for ${gemName}", e)
+            throw new ApiException("Count not retrieve list of versions for ${gemName}", e)
         }
     }
 
@@ -90,16 +105,33 @@ class DefaultRubyGemRestApi implements com.github.jrubygradle.api.core.RubyGemQu
      * @throw {@link com.github.jrubygradle.api.core.ApiException} if a networking error occurred or the GEM does not exist.
      */
     @Override
-    @SuppressWarnings('CatchThrowable')
     String latestVersion(String gemName) {
+        latestVersion(gemName, false)
+    }
+
+    /**
+     * Return latest published version of GEM.
+     *
+     * @param gemName Name of GEM.
+     * @param allowPrerelease Whether a prereleased version can be considered a latest version.
+     * @return Version of GEM
+     * @throws {@link ApiException} if GEM does not exist.
+     */
+    @Override
+    @SuppressWarnings('CatchThrowable')
+    String latestVersion(String gemName, boolean allowPrerelease) {
         String version
         try {
-            version = extractVersion(getData(V1, "versions/${gemName}/latest"))
+            if (allowPrerelease) {
+                version = allVersions(gemName, allowPrerelease).collect { GradleVersion.version(it) }.max().toString()
+            } else {
+                version = extractVersion(getData(V1, "versions/${gemName}/latest"))
+            }
         } catch (Throwable e) {
-            throw new com.github.jrubygradle.api.core.ApiException("Failed to retrieve latest version of ${gemName}", e)
+            throw new ApiException("Failed to retrieve latest version of ${gemName}", e)
         }
         if (version == 'unknown') {
-            throw new com.github.jrubygradle.api.core.ApiException("Cound not retrieve latest version of ${gemName}. Maybe it does not exist")
+            throw new ApiException("Cound not retrieve latest version of ${gemName}. Maybe it does not exist")
         }
         version
     }
@@ -117,9 +149,9 @@ class DefaultRubyGemRestApi implements com.github.jrubygradle.api.core.RubyGemQu
         try {
             extractMetadata(getData(V2, "rubygems/${gemName}/versions/${gemVersion}"))
         } catch (HttpException e) {
-            throw new com.github.jrubygradle.api.core.ApiException(":${gemName}:${gemVersion} not found", e)
+            throw new ApiException(":${gemName}:${gemVersion} not found", e)
         } catch (Throwable e) {
-            throw new com.github.jrubygradle.api.core.ApiException("Could not obtain information for :${gemName}:${gemVersion}.", e)
+            throw new ApiException("Could not obtain information for :${gemName}:${gemVersion}.", e)
         }
     }
 
@@ -148,8 +180,12 @@ class DefaultRubyGemRestApi implements com.github.jrubygradle.api.core.RubyGemQu
     }
 
     @CompileDynamic
-    private List<String> extractVersions(Object jsonParser) {
-        jsonParser*.number
+    private List<String> extractVersions(Object jsonParser, boolean includePrerelease) {
+        if (includePrerelease) {
+            jsonParser*.number
+        } else {
+            jsonParser.findAll { !it.prerelease }*.number
+        }
     }
 
     @CompileDynamic
diff --git a/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/IvyXmlGlobalProxyRegistry.groovy b/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/IvyXmlGlobalProxyRegistry.groovy
index 40e05b49..8077d48f 100644
--- a/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/IvyXmlGlobalProxyRegistry.groovy
+++ b/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/IvyXmlGlobalProxyRegistry.groovy
@@ -23,6 +23,7 @@
  */
 package com.github.jrubygradle.internal.core
 
+import com.github.jrubygradle.api.core.GemRepositoryConfiguration
 import groovy.transform.CompileStatic
 import org.gradle.api.Project
 
@@ -54,8 +55,17 @@ class IvyXmlGlobalProxyRegistry {
      * @param group Group name for GEMs that will be fected from the remote.
      * @return Access to a proxy sever. If the server does not exist it will be created.
      */
-    com.github.jrubygradle.api.core.IvyXmlProxyServer registerProxy(URI remoteURI, String group) {
-        com.github.jrubygradle.api.core.IvyXmlProxyServer proxy = getOrCreateServer(remoteURI, group, new File(rootCacheDir, uriHash(remoteURI)))
+    com.github.jrubygradle.api.core.IvyXmlProxyServer registerProxy(
+        URI remoteURI,
+        String group,
+        GemRepositoryConfiguration grc
+    ) {
+        com.github.jrubygradle.api.core.IvyXmlProxyServer proxy = getOrCreateServer(
+            remoteURI,
+            group,
+            new File(rootCacheDir, uriHash(remoteURI)),
+            grc
+        )
         proxy.refreshDependencies = refresh
         proxy
     }
@@ -68,10 +78,11 @@ class IvyXmlGlobalProxyRegistry {
     static private com.github.jrubygradle.api.core.IvyXmlProxyServer getOrCreateServer(
         URI uri,
         String group,
-        File cacheDir
+        File cacheDir,
+        GemRepositoryConfiguration grc
     ) {
         SERVER_MAP.computeIfAbsent(uri, {
-            com.github.jrubygradle.api.core.IvyXmlProxyServer server = createProxyServer(uri, group, cacheDir)
+            com.github.jrubygradle.api.core.IvyXmlProxyServer server = createProxyServer(uri, group, cacheDir, grc)
             server.run()
             server
         })
@@ -80,9 +91,10 @@ class IvyXmlGlobalProxyRegistry {
     static private com.github.jrubygradle.api.core.IvyXmlProxyServer createProxyServer(
         URI uri,
         String group,
-        File cacheDir
+        File cacheDir,
+        GemRepositoryConfiguration grc
     ) {
-        new IvyXmlRatpackProxyServer(cacheDir, uri, group)
+        new IvyXmlRatpackProxyServer(cacheDir, uri, group, grc)
     }
 
     static private final ConcurrentMap<URI, com.github.jrubygradle.api.core.IvyXmlProxyServer> SERVER_MAP = new ConcurrentHashMap<>()
diff --git a/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/IvyXmlRatpackProxyServer.java b/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/IvyXmlRatpackProxyServer.java
index c4204dbf..150b312f 100644
--- a/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/IvyXmlRatpackProxyServer.java
+++ b/core-plugin/src/main/groovy/com/github/jrubygradle/internal/core/IvyXmlRatpackProxyServer.java
@@ -23,6 +23,7 @@
  */
 package com.github.jrubygradle.internal.core;
 
+import com.github.jrubygradle.api.core.GemRepositoryConfiguration;
 import ratpack.server.RatpackServer;
 
 import java.io.File;
@@ -46,9 +47,15 @@ public class IvyXmlRatpackProxyServer extends AbstractIvyXmlProxyServer {
      * @param cache     Root directory for local Ivy XML cache.
      * @param serverUri URI of remote Rubygems proxy.
      * @param group     Group that will be associated with the Rubygems proxy.
+     * @param grc       Additional configuration regarding remote GEM server
      */
-    public IvyXmlRatpackProxyServer(File cache, URI serverUri, String group) {
-        super(cache, serverUri, group);
+    public IvyXmlRatpackProxyServer(
+            File cache,
+            URI serverUri,
+            String group,
+            GemRepositoryConfiguration grc
+    ) {
+        super(cache, serverUri, group, grc);
     }
 
     /**
diff --git a/core-plugin/src/test/groovy/com/github/jrubygradle/api/core/IvyXmlProxyServerSpec.groovy b/core-plugin/src/test/groovy/com/github/jrubygradle/api/core/IvyXmlProxyServerSpec.groovy
index 449ffc1b..9ab04fd8 100644
--- a/core-plugin/src/test/groovy/com/github/jrubygradle/api/core/IvyXmlProxyServerSpec.groovy
+++ b/core-plugin/src/test/groovy/com/github/jrubygradle/api/core/IvyXmlProxyServerSpec.groovy
@@ -42,7 +42,12 @@ class IvyXmlProxyServerSpec extends Specification {
     TemporaryFolder projectRoot
 
     void setup() {
-        server = new IvyXmlRatpackProxyServer(projectRoot.root, 'https://rubygems.org'.toURI(), 'rubygems')
+        server = new IvyXmlRatpackProxyServer(
+            projectRoot.root,
+            'https://rubygems.org'.toURI(),
+            'rubygems',
+            new GemRepositoryConfiguration()
+        )
         server.run()
         httpBuilder = OkHttpBuilder.configure {
             request.uri = server.bindAddress
diff --git a/gradle.properties b/gradle.properties
index 29bf97a0..f0bbf264 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,4 +1,4 @@
-version=2.0.0-alpha.6
+version=2.0.0-alpha.7
 group=com.github.jruby-gradle
 copyrightYear=2014-2019