Add update steps for namespaces

This adds a new update step API dedicated
to handle namespace related data.

Pushed-by: Rene Pfeuffer<rene.pfeuffer@cloudogu.com>
Co-authored-by: René Pfeuffer<rene.pfeuffer@cloudogu.com>
Committed-by: René Pfeuffer<rene.pfeuffer@cloudogu.com>

gradle/changelog/namespace_update_steps.yaml

@@ -0,0 +1,2 @@
+- type: added
+  description: Update steps for namespaces

scm-core/src/main/java/sonia/scm/migration/NamespaceUpdateContext.java

@@ -0,0 +1,46 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * 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 sonia.scm.migration;
+
+/**
+ * Data for the namespace, whose data that should be migrated.
+ *
+ * @since 2.47.0
+ */
+public final class NamespaceUpdateContext {
+
+  private final String namespace;
+
+  public NamespaceUpdateContext(String namespace) {
+    this.namespace = namespace;
+  }
+
+  /**
+   * The name of the namespace, whose data should be migrated.
+   */
+  public String getNamespace() {
+    return namespace;
+  }
+}

scm-core/src/main/java/sonia/scm/migration/NamespaceUpdateStep.java

@@ -0,0 +1,52 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * 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 sonia.scm.migration;
+
+import sonia.scm.plugin.ExtensionPoint;
+
+/**
+ * This is the main interface for "namespace specific" data migration/update. Using this interface, SCM-Manager
+ * provides the possibility to change data structures between versions for a given type of data. This class should be
+ * used only for namespace specific data (eg. the store is created with a call of <code>forNamespace</code> in a store
+ * factory. To migrate global data, use a {@link UpdateStep}.
+ * <p>For information about {@link #getAffectedDataType()} and {@link #getTargetVersion()}, see the package
+ * documentation.</p>
+ *
+ * @see sonia.scm.migration
+ *
+ * @since 2.47.0
+ */
+@ExtensionPoint
+public interface NamespaceUpdateStep extends UpdateStepTarget {
+  /**
+   * Implement this to update the data to the new version for a specific namespace. If any {@link Exception} is thrown,
+   * SCM-Manager will not start up.
+   *
+   * @param namespaceUpdateContext A context providing specifics about the namespace, whose data should be migrated
+   *                                (eg. its name).
+   */
+  @SuppressWarnings("java:S112") // we suppress this one, because an implementation should feel free to throw any exception it deems necessary
+  void doUpdate(NamespaceUpdateContext namespaceUpdateContext) throws Exception;
+}

scm-core/src/main/java/sonia/scm/update/NamespaceUpdateIterator.java

@@ -0,0 +1,75 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * 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 sonia.scm.update;
+
+import sonia.scm.migration.UpdateException;
+
+import java.util.function.Consumer;
+
+/**
+ * Implementations of this interface can be used to iterate all namespaces in update steps.
+ *
+ * @since 2.47.0
+ */
+public interface NamespaceUpdateIterator {
+
+  /**
+   * Calls the given consumer with each namespace.
+   *
+   * @since 2.47.0
+   */
+  void forEachNamespace(Consumer<String> namespace);
+
+  /**
+   * Equivalent to {@link #forEachNamespace(Consumer)} with the difference, that you can throw exceptions in the given
+   * update code, that will then be wrapped in a {@link UpdateException}.
+   *
+   * @since 2.47.0
+   */
+  default void updateEachNamespace(Updater updater) {
+    forEachNamespace(
+      namespace -> {
+        try {
+          updater.update(namespace);
+        } catch (Exception e) {
+          throw new UpdateException("failed to update namespace " + namespace, e);
+        }
+      }
+    );
+  }
+
+  /**
+   * Simple callback with the name of an existing namespace with the possibility to throw exceptions.
+   *
+   * @since 2.47.0
+   */
+  interface Updater {
+    /**
+     * Implements the update logic for a single namespace, denoted by its name.
+     */
+    @SuppressWarnings("java:S112") // We explicitly want to allow arbitrary exceptions here
+    void update(String namespace) throws Exception;
+  }
+}

scm-dao-xml/src/main/java/sonia/scm/store/FileNamespaceUpdateIterator.java

@@ -0,0 +1,70 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * 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 sonia.scm.store;
+
+import sonia.scm.migration.UpdateException;
+import sonia.scm.repository.Repository;
+import sonia.scm.repository.RepositoryLocationResolver;
+import sonia.scm.update.NamespaceUpdateIterator;
+
+import javax.inject.Inject;
+import javax.xml.bind.JAXBContext;
+import javax.xml.bind.JAXBException;
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.function.Consumer;
+
+public class FileNamespaceUpdateIterator implements NamespaceUpdateIterator {
+
+  private final RepositoryLocationResolver locationResolver;
+  private final JAXBContext jaxbContext;
+
+  @Inject
+  public FileNamespaceUpdateIterator(RepositoryLocationResolver locationResolver) {
+    this.locationResolver = locationResolver;
+    try {
+      jaxbContext = JAXBContext.newInstance(Repository.class);
+    } catch (JAXBException ex) {
+      throw new IllegalStateException("failed to create jaxb context for repository", ex);
+    }
+  }
+
+  @Override
+  public void forEachNamespace(Consumer<String> namespaceConsumer) {
+    Collection<String> namespaces = new HashSet<>();
+    locationResolver
+      .forClass(Path.class)
+      .forAllLocations((repositoryId, path) -> {
+        try {
+          Repository metadata = (Repository) jaxbContext.createUnmarshaller().unmarshal(path.resolve("metadata.xml").toFile());
+          namespaces.add(metadata.getNamespace());
+        } catch (JAXBException e) {
+          throw new UpdateException("Failed to read metadata for repository " + repositoryId, e);
+        }
+      });
+    namespaces.forEach(namespaceConsumer);
+  }
+}

scm-dao-xml/src/test/java/sonia/scm/store/FileNamespaceUpdateIteratorTest.java

@@ -0,0 +1,68 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * 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 sonia.scm.store;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.api.io.TempDir;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import sonia.scm.TempDirRepositoryLocationResolver;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.Collection;
+
+import static java.util.Arrays.asList;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class FileNamespaceUpdateIteratorTest {
+
+  private TempDirRepositoryLocationResolver locationResolver;
+
+  @BeforeEach
+  void initLocationResolver(@TempDir Path tempDir) throws IOException {
+    locationResolver = new TempDirRepositoryLocationResolver(tempDir.toFile());
+    Files.write(tempDir.resolve("metadata.xml"), asList(
+      "<repositories>",
+      "  <namespace>hitchhike</namespace>",
+      "</repositories>"
+    ));
+  }
+
+  @Test
+  void shouldFindNamespaces() {
+    Collection<String> foundNamespaces = new ArrayList<>();
+    new FileNamespaceUpdateIterator(locationResolver)
+      .forEachNamespace(foundNamespaces::add);
+
+    assertThat(foundNamespaces).containsExactly("hitchhike");
+  }
+}

scm-test/src/main/java/sonia/scm/store/InMemoryByteConfigurationEntryStore.java

@@ -37,7 +37,7 @@ import java.util.Map;
 
 public class InMemoryByteConfigurationEntryStore<V> implements ConfigurationEntryStore<V> {
 
-  private final Class<V> type;
+  private Class<V> type;
   private final KeyGenerator generator = new UUIDKeyGenerator();
   private final Map<String, byte[]> store = new HashMap<>();
 
@@ -104,4 +104,8 @@ public class InMemoryByteConfigurationEntryStore<V> implements ConfigurationEntr
     }
     return null;
   }
+
+  void overrideType(Class<V> type) {
+    this.type = type;
+  }
 }

scm-test/src/main/java/sonia/scm/store/InMemoryByteConfigurationEntryStoreFactory.java

@@ -51,6 +51,8 @@ public class InMemoryByteConfigurationEntryStoreFactory implements Configuration
 
   @SuppressWarnings("unchecked")
   public <T> ConfigurationEntryStore<T> get(Class<T> type, String name) {
-    return stores.computeIfAbsent(name, n -> new InMemoryByteConfigurationEntryStore<>(type));
+    InMemoryByteConfigurationEntryStore<T> store = stores.computeIfAbsent(name, n -> new InMemoryByteConfigurationEntryStore<>(type));
+    store.overrideType(type);
+    return store;
   }
 }

scm-test/src/main/java/sonia/scm/store/InMemoryByteConfigurationStore.java

@@ -34,7 +34,7 @@ import java.nio.charset.StandardCharsets;
  */
 public class InMemoryByteConfigurationStore<T> implements ConfigurationStore<T> {
 
-  private final Class<T> type;
+  private Class<T> type;
   byte[] store;
 
   public InMemoryByteConfigurationStore(Class<T> type) {
@@ -73,4 +73,8 @@ public class InMemoryByteConfigurationStore<T> implements ConfigurationStore<T>
   public void setRawXml(String xml) {
     store = xml.getBytes(StandardCharsets.UTF_8);
   }
+
+  void overrideType(Class<T> type) {
+    this.type = type;
+  }
 }

scm-test/src/main/java/sonia/scm/store/InMemoryByteConfigurationStoreFactory.java

@@ -46,6 +46,8 @@ public class InMemoryByteConfigurationStoreFactory implements ConfigurationStore
 
   @SuppressWarnings("unchecked")
   public <T> ConfigurationStore<T> getStore(Class<T> type, String name) {
-    return stores.computeIfAbsent(name, n -> new InMemoryByteConfigurationStore<>(type));
+    InMemoryByteConfigurationStore<T> store = stores.computeIfAbsent(name, n -> new InMemoryByteConfigurationStore<>(type));
+    store.overrideType(type);
+    return store;
   }
 }

scm-test/src/main/java/sonia/scm/store/InMemoryByteDataStore.java

@@ -37,7 +37,7 @@ import java.util.Map;
 
 public class InMemoryByteDataStore<T> implements DataStore<T> {
 
-  private final Class<T> type;
+  private Class<T> type;
   private final KeyGenerator generator = new UUIDKeyGenerator();
   private final Map<String, byte[]> store = new HashMap<>();
 
@@ -104,4 +104,8 @@ public class InMemoryByteDataStore<T> implements DataStore<T> {
     }
     return null;
   }
+
+  void overrideType(Class<T> type) {
+    this.type = type;
+  }
 }

scm-test/src/main/java/sonia/scm/store/InMemoryByteDataStoreFactory.java

@@ -47,6 +47,8 @@ public class InMemoryByteDataStoreFactory implements DataStoreFactory, InMemoryS
 
   @SuppressWarnings("unchecked")
   public  <T> DataStore<T> getStore(Class<T> type, String name) {
-    return stores.computeIfAbsent(name, n -> new InMemoryByteDataStore<>(type));
+    InMemoryByteDataStore<T> store = stores.computeIfAbsent(name, n -> new InMemoryByteDataStore<>(type));
+    store.overrideType(type);
+    return store;
   }
 }

scm-webapp/src/main/java/sonia/scm/lifecycle/modules/BootstrapModule.java

@@ -61,6 +61,7 @@ import sonia.scm.store.ConfigurationStoreFactory;
 import sonia.scm.store.DataStoreFactory;
 import sonia.scm.store.DefaultBlobDirectoryAccess;
 import sonia.scm.store.FileBlobStoreFactory;
+import sonia.scm.store.FileNamespaceUpdateIterator;
 import sonia.scm.store.FileRepositoryUpdateIterator;
 import sonia.scm.store.FileStoreUpdateStepUtilFactory;
 import sonia.scm.store.JAXBConfigurationEntryStoreFactory;
@@ -68,6 +69,7 @@ import sonia.scm.store.JAXBConfigurationStoreFactory;
 import sonia.scm.store.JAXBDataStoreFactory;
 import sonia.scm.store.JAXBPropertyFileAccess;
 import sonia.scm.update.BlobDirectoryAccess;
+import sonia.scm.update.NamespaceUpdateIterator;
 import sonia.scm.update.PropertyFileAccess;
 import sonia.scm.update.RepositoryUpdateIterator;
 import sonia.scm.update.StoreUpdateStepUtilFactory;
@@ -124,6 +126,7 @@ public class BootstrapModule extends AbstractModule {
     bind(PropertyFileAccess.class, JAXBPropertyFileAccess.class);
     bind(BlobDirectoryAccess.class, DefaultBlobDirectoryAccess.class);
     bind(RepositoryUpdateIterator.class, FileRepositoryUpdateIterator.class);
+    bind(NamespaceUpdateIterator.class, FileNamespaceUpdateIterator.class);
     bind(StoreUpdateStepUtilFactory.class, FileStoreUpdateStepUtilFactory.class);
     bind(new TypeLiteral<UpdateStepRepositoryMetadataAccess<Path>>() {}).to(new TypeLiteral<MetadataStore>() {});
 

scm-webapp/src/main/java/sonia/scm/lifecycle/modules/UpdateStepModule.java

@@ -26,6 +26,7 @@ package sonia.scm.lifecycle.modules;
 
 import com.google.inject.AbstractModule;
 import com.google.inject.multibindings.Multibinder;
+import sonia.scm.migration.NamespaceUpdateStep;
 import sonia.scm.migration.RepositoryUpdateStep;
 import sonia.scm.migration.UpdateStep;
 import sonia.scm.plugin.PluginLoader;
@@ -41,7 +42,8 @@ public class UpdateStepModule extends AbstractModule {
   @Override
   protected void configure() {
     Multibinder<UpdateStep> updateStepBinder = Multibinder.newSetBinder(binder(), UpdateStep.class);
-    Multibinder<RepositoryUpdateStep> repositoryUdateStepBinder = Multibinder.newSetBinder(binder(), RepositoryUpdateStep.class);
+    Multibinder<RepositoryUpdateStep> repositoryUpdateStepBinder = Multibinder.newSetBinder(binder(), RepositoryUpdateStep.class);
+    Multibinder<NamespaceUpdateStep> namespaceUpdateStepBinder = Multibinder.newSetBinder(binder(), NamespaceUpdateStep.class);
     pluginLoader
       .getExtensionProcessor()
       .byExtensionPoint(UpdateStep.class)
@@ -49,6 +51,10 @@ public class UpdateStepModule extends AbstractModule {
     pluginLoader
       .getExtensionProcessor()
       .byExtensionPoint(RepositoryUpdateStep.class)
-      .forEach(stepClass -> repositoryUdateStepBinder.addBinding().to(stepClass));
+      .forEach(stepClass -> repositoryUpdateStepBinder.addBinding().to(stepClass));
+    pluginLoader
+      .getExtensionProcessor()
+      .byExtensionPoint(NamespaceUpdateStep.class)
+      .forEach(stepClass -> namespaceUpdateStepBinder.addBinding().to(stepClass));
   }
 }

scm-webapp/src/main/java/sonia/scm/update/UpdateEngine.java

@@ -26,6 +26,8 @@ package sonia.scm.update;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import sonia.scm.migration.NamespaceUpdateContext;
+import sonia.scm.migration.NamespaceUpdateStep;
 import sonia.scm.migration.RepositoryUpdateContext;
 import sonia.scm.migration.RepositoryUpdateStep;
 import sonia.scm.migration.UpdateException;
@@ -46,28 +48,33 @@ public class UpdateEngine {
 
   public static final Logger LOG = LoggerFactory.getLogger(UpdateEngine.class);
 
-
   private final List<UpdateStepWrapper> steps;
   private final RepositoryUpdateIterator repositoryUpdateIterator;
+  private final NamespaceUpdateIterator namespaceUpdateIterator;
   private final UpdateStepStore updateStepStore;
 
   @Inject
   public UpdateEngine(
     Set<UpdateStep> globalSteps,
     Set<RepositoryUpdateStep> repositorySteps,
+    Set<NamespaceUpdateStep> namespaceSteps,
     RepositoryUpdateIterator repositoryUpdateIterator,
-    UpdateStepStore updateStepStore) {
+    NamespaceUpdateIterator namespaceUpdateIterator, UpdateStepStore updateStepStore) {
     this.repositoryUpdateIterator = repositoryUpdateIterator;
+    this.namespaceUpdateIterator = namespaceUpdateIterator;
     this.updateStepStore = updateStepStore;
-    this.steps = sortSteps(globalSteps, repositorySteps);
+    this.steps = sortSteps(globalSteps, repositorySteps, namespaceSteps);
   }
 
-  private List<UpdateStepWrapper> sortSteps(Set<UpdateStep> globalSteps, Set<RepositoryUpdateStep> repositorySteps) {
+  private List<UpdateStepWrapper> sortSteps(Set<UpdateStep> globalSteps, Set<RepositoryUpdateStep> repositorySteps, Set<NamespaceUpdateStep> namespaceSteps) {
     LOG.trace("sorting available update steps:");
     List<UpdateStepWrapper> sortedSteps =
       concat(
-        globalSteps.stream().filter(this::notRunYet).map(GlobalUpdateStepWrapper::new),
-        repositorySteps.stream().map(RepositoryUpdateStepWrapper::new))
+        concat(
+          globalSteps.stream().filter(this::notRunYet).map(GlobalUpdateStepWrapper::new),
+          repositorySteps.stream().map(RepositoryUpdateStepWrapper::new)),
+        namespaceSteps.stream().map(NamespaceUpdateStepWrapper::new)
+      )
       .sorted(
         Comparator
           .comparing(UpdateStepWrapper::getTargetVersion)
@@ -248,4 +255,52 @@ public class UpdateEngine {
       return updateStepStore.notRunYet(repositoryId, delegate);
     }
   }
+
+  private class NamespaceUpdateStepWrapper extends UpdateStepWrapper {
+
+    private final NamespaceUpdateStep delegate;
+
+    public NamespaceUpdateStepWrapper(NamespaceUpdateStep delegate) {
+      super(delegate);
+      this.delegate = delegate;
+    }
+
+    @Override
+    public boolean isGlobalUpdateStep() {
+      return false;
+    }
+
+    @Override
+    boolean isCoreUpdate() {
+      return false;
+    }
+
+    @Override
+    void doUpdate() {
+      namespaceUpdateIterator.updateEachNamespace(this::doUpdate);
+    }
+
+    @Override
+    void doUpdate(String namespace) throws Exception {
+      if (notRunYet(namespace)) {
+        LOG.info("running update step for type {} and version {} (class {}) for namespace {}",
+          delegate.getAffectedDataType(),
+          delegate.getTargetVersion(),
+          delegate.getClass().getName(),
+          namespace
+        );
+        delegate.doUpdate(new NamespaceUpdateContext(namespace));
+        updateStepStore.storeExecutedUpdate(namespace, delegate);
+      }
+    }
+
+    private boolean notRunYet(String namespace) {
+      LOG.trace("checking whether to run update step for type {} and version {} on namespace {}",
+        delegate.getAffectedDataType(),
+        delegate.getTargetVersion(),
+        namespace
+      );
+      return updateStepStore.notRunYet(namespace, delegate);
+    }
+  }
 }

scm-webapp/src/main/java/sonia/scm/update/UpdateStepStore.java

@@ -26,6 +26,7 @@ package sonia.scm.update;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import sonia.scm.migration.NamespaceUpdateStep;
 import sonia.scm.migration.RepositoryUpdateStep;
 import sonia.scm.migration.UpdateStep;
 import sonia.scm.migration.UpdateStepTarget;
@@ -52,6 +53,11 @@ class UpdateStepStore {
     storeNewVersion(store, updateStep);
   }
 
+  void storeExecutedUpdate(String namespace, NamespaceUpdateStep updateStep) {
+    ConfigurationEntryStore<UpdateVersionInfo> store = createNamespaceStore(namespace);
+    storeNewVersion(store, updateStep);
+  }
+
   void storeExecutedUpdate(UpdateStep updateStep) {
     ConfigurationEntryStore<UpdateVersionInfo> store = createGlobalStore();
     storeNewVersion(store, updateStep);
@@ -65,6 +71,10 @@ class UpdateStepStore {
     return notRunYet(createRepositoryStore(repositoryId), updateStep);
   }
 
+  boolean notRunYet(String namespace, NamespaceUpdateStep updateStep) {
+    return notRunYet(createNamespaceStore(namespace), updateStep);
+  }
+
   private void storeNewVersion(ConfigurationEntryStore<UpdateVersionInfo> store, UpdateStepTarget updateStep) {
     UpdateVersionInfo newVersionInfo = new UpdateVersionInfo(updateStep.getTargetVersion().getParsedVersion());
     store.put(updateStep.getAffectedDataType(), newVersionInfo);
@@ -99,4 +109,12 @@ class UpdateStepStore {
       .forRepository(repositoryId)
       .build();
   }
+
+  private ConfigurationEntryStore<UpdateVersionInfo> createNamespaceStore(String namespace) {
+    return storeFactory
+      .withType(UpdateVersionInfo.class)
+      .withName(STORE_NAME)
+      .forNamespace(namespace)
+      .build();
+  }
 }

scm-webapp/src/test/java/sonia/scm/update/UpdateEngineTest.java

@@ -26,6 +26,8 @@ package sonia.scm.update;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import sonia.scm.migration.NamespaceUpdateContext;
+import sonia.scm.migration.NamespaceUpdateStep;
 import sonia.scm.migration.RepositoryUpdateContext;
 import sonia.scm.migration.RepositoryUpdateStep;
 import sonia.scm.migration.UpdateStep;
@@ -52,6 +54,7 @@ class UpdateEngineTest {
 
   ConfigurationEntryStoreFactory storeFactory = new InMemoryByteConfigurationEntryStoreFactory();
   RepositoryUpdateIterator repositoryUpdateIterator = mock(RepositoryUpdateIterator.class, CALLS_REAL_METHODS);
+  NamespaceUpdateIterator namespaceUpdateIterator = mock(NamespaceUpdateIterator.class, CALLS_REAL_METHODS);
   UpdateStepStore updateStepStore = new UpdateStepStore(storeFactory);
 
   List<String> processedUpdates = new ArrayList<>();
@@ -66,6 +69,16 @@ class UpdateEngineTest {
     }).when(repositoryUpdateIterator).forEachRepository(any());
   }
 
+  @BeforeEach
+  void mockNamespaces() {
+    doAnswer(invocation -> {
+      Consumer<String> consumer = invocation.getArgument(0, Consumer.class);
+      consumer.accept("hitchhikers");
+      consumer.accept("vogons");
+      return null;
+    }).when(namespaceUpdateIterator).forEachNamespace(any());
+  }
+
   @Test
   void shouldProcessStepsInCorrectOrder() {
     LinkedHashSet<UpdateStep> updateSteps = new LinkedHashSet<>();
@@ -74,7 +87,7 @@ class UpdateEngineTest {
     updateSteps.add(new FixedVersionUpdateStep("test", "1.2.0"));
     updateSteps.add(new FixedVersionUpdateStep("test", "1.1.0"));
 
-    UpdateEngine updateEngine = new UpdateEngine(updateSteps, emptySet(), repositoryUpdateIterator, updateStepStore);
+    UpdateEngine updateEngine = new UpdateEngine(updateSteps, emptySet(), emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     updateEngine.update();
 
     assertThat(processedUpdates)
@@ -90,7 +103,7 @@ class UpdateEngineTest {
     updateSteps.add(new FixedVersionUpdateStep("test", "1.2.0"));
     repositoryUpdateSteps.add(new FixedVersionUpdateStep("test", "1.1.0"));
 
-    UpdateEngine updateEngine = new UpdateEngine(updateSteps, repositoryUpdateSteps, repositoryUpdateIterator, updateStepStore);
+    UpdateEngine updateEngine = new UpdateEngine(updateSteps, repositoryUpdateSteps, emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     updateEngine.update();
 
     assertThat(processedUpdates)
@@ -106,13 +119,29 @@ class UpdateEngineTest {
     repositoryUpdateSteps.add(new FixedVersionUpdateStep("test", "1.1.1"));
     repositoryUpdateSteps.add(new FixedVersionUpdateStep("test", "1.1.0"));
 
-    UpdateEngine updateEngine = new UpdateEngine(updateSteps, repositoryUpdateSteps, repositoryUpdateIterator, updateStepStore);
+    UpdateEngine updateEngine = new UpdateEngine(updateSteps, repositoryUpdateSteps, emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     updateEngine.update("1337");
 
     assertThat(processedUpdates)
       .containsExactly("test:1.1.0-1337", "test:1.1.1-1337");
   }
 
+  @Test
+  void shouldProcessStepsForSingleNamespace() {
+    LinkedHashSet<UpdateStep> updateSteps = new LinkedHashSet<>();
+    LinkedHashSet<NamespaceUpdateStep> namespaceUpdateSteps = new LinkedHashSet<>();
+
+    updateSteps.add(new FixedVersionUpdateStep("test", "1.2.0"));
+    namespaceUpdateSteps.add(new FixedVersionUpdateStep("test", "1.1.1"));
+    namespaceUpdateSteps.add(new FixedVersionUpdateStep("test", "1.1.0"));
+
+    UpdateEngine updateEngine = new UpdateEngine(updateSteps, emptySet(), namespaceUpdateSteps, repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
+    updateEngine.update("hitchhikers");
+
+    assertThat(processedUpdates)
+      .containsExactly("test:1.1.0/hitchhikers", "test:1.1.1/hitchhikers");
+  }
+
   @Test
   void shouldProcessCoreStepsBeforeOther() {
     LinkedHashSet<UpdateStep> updateSteps = new LinkedHashSet<>();
@@ -120,7 +149,7 @@ class UpdateEngineTest {
     updateSteps.add(new FixedVersionUpdateStep("test", "1.2.0"));
     updateSteps.add(new CoreFixedVersionUpdateStep("core", "1.2.0"));
 
-    UpdateEngine updateEngine = new UpdateEngine(updateSteps, emptySet(), repositoryUpdateIterator, updateStepStore);
+    UpdateEngine updateEngine = new UpdateEngine(updateSteps, emptySet(), emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     updateEngine.update();
 
     assertThat(processedUpdates)
@@ -132,7 +161,7 @@ class UpdateEngineTest {
     Set<UpdateStep> updateSteps = singleton(new FixedVersionUpdateStep("test", "1.2.0"));
     Set<RepositoryUpdateStep> repositoryUpdateSteps = singleton(new FixedVersionUpdateStep("test", "1.2.0"));
 
-    UpdateEngine updateEngine = new UpdateEngine(updateSteps, repositoryUpdateSteps, repositoryUpdateIterator, updateStepStore);
+    UpdateEngine updateEngine = new UpdateEngine(updateSteps, repositoryUpdateSteps, emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     updateEngine.update();
 
     assertThat(processedUpdates)
@@ -145,12 +174,12 @@ class UpdateEngineTest {
 
     updateSteps.add(new FixedVersionUpdateStep("test", "1.1.1"));
 
-    UpdateEngine firstUpdateEngine = new UpdateEngine(updateSteps, emptySet(), repositoryUpdateIterator, updateStepStore);
+    UpdateEngine firstUpdateEngine = new UpdateEngine(updateSteps, emptySet(), emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     firstUpdateEngine.update();
 
     processedUpdates.clear();
 
-    UpdateEngine secondUpdateEngine = new UpdateEngine(updateSteps, emptySet(), repositoryUpdateIterator, updateStepStore);
+    UpdateEngine secondUpdateEngine = new UpdateEngine(updateSteps, emptySet(), emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     secondUpdateEngine.update();
 
     assertThat(processedUpdates).isEmpty();
@@ -162,39 +191,58 @@ class UpdateEngineTest {
 
     repositoryUpdateSteps.add(new FixedVersionUpdateStep("test", "1.1.1"));
 
-    UpdateEngine firstUpdateEngine = new UpdateEngine(emptySet(), repositoryUpdateSteps, repositoryUpdateIterator, updateStepStore);
+    UpdateEngine firstUpdateEngine = new UpdateEngine(emptySet(), repositoryUpdateSteps, emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     firstUpdateEngine.update();
 
     processedUpdates.clear();
 
     repositoryUpdateSteps.add(new FixedVersionUpdateStep("test", "1.2.0"));
-    UpdateEngine secondUpdateEngine = new UpdateEngine(emptySet(), repositoryUpdateSteps, repositoryUpdateIterator, updateStepStore);
+    UpdateEngine secondUpdateEngine = new UpdateEngine(emptySet(), repositoryUpdateSteps, emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     secondUpdateEngine.update();
 
     assertThat(processedUpdates)
       .containsExactly("test:1.2.0-42", "test:1.2.0-1337");
   }
 
+  @Test
+  void shouldRunNamespaceStepsOnlyOnce() {
+    LinkedHashSet<NamespaceUpdateStep> namespaceUpdateSteps = new LinkedHashSet<>();
+
+    namespaceUpdateSteps.add(new FixedVersionUpdateStep("test", "1.1.1"));
+
+    UpdateEngine firstUpdateEngine = new UpdateEngine(emptySet(), emptySet(), namespaceUpdateSteps, repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
+    firstUpdateEngine.update();
+
+    processedUpdates.clear();
+
+    namespaceUpdateSteps.add(new FixedVersionUpdateStep("test", "1.2.0"));
+    UpdateEngine secondUpdateEngine = new UpdateEngine(emptySet(), emptySet(), namespaceUpdateSteps, repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
+    secondUpdateEngine.update();
+
+    assertThat(processedUpdates)
+      .containsExactly("test:1.2.0/hitchhikers", "test:1.2.0/vogons");
+  }
+
   @Test
   void shouldRunStepsForDifferentTypesIndependently() {
     LinkedHashSet<UpdateStep> updateSteps = new LinkedHashSet<>();
 
     updateSteps.add(new FixedVersionUpdateStep("test", "1.1.1"));
 
-    UpdateEngine updateEngine = new UpdateEngine(updateSteps, emptySet(), repositoryUpdateIterator, updateStepStore);
+    UpdateEngine updateEngine = new UpdateEngine(updateSteps, emptySet(), emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     updateEngine.update();
 
     processedUpdates.clear();
 
     updateSteps.add(new FixedVersionUpdateStep("other", "1.1.1"));
 
-    updateEngine = new UpdateEngine(updateSteps, emptySet(), repositoryUpdateIterator, updateStepStore);
+    updateEngine = new UpdateEngine(updateSteps, emptySet(), emptySet(), repositoryUpdateIterator, namespaceUpdateIterator, updateStepStore);
     updateEngine.update();
 
     assertThat(processedUpdates).containsExactly("other:1.1.1");
   }
 
-  class FixedVersionUpdateStep implements UpdateStep, RepositoryUpdateStep {
+  class FixedVersionUpdateStep implements UpdateStep, RepositoryUpdateStep, NamespaceUpdateStep {
     private final String type;
     private final String version;
 
@@ -222,6 +270,11 @@ class UpdateEngineTest {
     public void doUpdate(RepositoryUpdateContext repositoryUpdateContext) throws Exception {
       processedUpdates.add(type + ":" + version + "-" + repositoryUpdateContext.getRepositoryId());
     }
+
+    @Override
+    public void doUpdate(NamespaceUpdateContext namespaceUpdateContext) throws Exception {
+      processedUpdates.add(type + ":" + version + "/" + namespaceUpdateContext.getNamespace());
+    }
   }
 
   class CoreFixedVersionUpdateStep extends FixedVersionUpdateStep implements CoreUpdateStep {