Merge pull request #13543 from vespa-engine/revert-13534-musum/configserver-refactoring-8

Revert "Merge SessionFactory into SessionRepository"

6 files changed, 323 insertions, 254 deletions

diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java b/configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java
index ce6b4587ada..af5a561aa6e 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java
@@ -53,6 +53,7 @@ import com.yahoo.vespa.config.server.session.SessionRepository;
 import com.yahoo.vespa.config.server.session.PrepareParams;
 import com.yahoo.vespa.config.server.session.RemoteSession;
 import com.yahoo.vespa.config.server.session.Session;
+import com.yahoo.vespa.config.server.session.SessionFactory;
 import com.yahoo.vespa.config.server.session.SilentDeployLogger;
 import com.yahoo.vespa.config.server.tenant.ApplicationRolesStore;
 import com.yahoo.vespa.config.server.tenant.ContainerEndpointsCache;
@@ -302,7 +303,7 @@ public class ApplicationRepository implements com.yahoo.config.provision.Deploye
         LocalSession activeSession = getActiveLocalSession(tenant, application);
         if (activeSession == null) return Optional.empty();
         TimeoutBudget timeoutBudget = new TimeoutBudget(clock, timeout);
-        LocalSession newSession = tenant.getSessionRepository().createSessionFromExisting(activeSession, logger, true, timeoutBudget);
+        LocalSession newSession = tenant.getSessionFactory().createSessionFromExisting(activeSession, logger, true, timeoutBudget);
         tenant.getSessionRepository().addSession(newSession);
 
         return Optional.of(Deployment.unprepared(newSession, this, hostProvisioner, tenant, timeout, clock,
@@ -634,8 +635,9 @@ public class ApplicationRepository implements com.yahoo.config.provision.Deploye
                                           TimeoutBudget timeoutBudget) {
         Tenant tenant = tenantRepository.getTenant(applicationId.tenant());
         SessionRepository sessionRepository = tenant.getSessionRepository();
+        SessionFactory sessionFactory = tenant.getSessionFactory();
         RemoteSession fromSession = getExistingSession(tenant, applicationId);
-        LocalSession session = sessionRepository.createSessionFromExisting(fromSession, logger, internalRedeploy, timeoutBudget);
+        LocalSession session = sessionFactory.createSessionFromExisting(fromSession, logger, internalRedeploy, timeoutBudget);
         sessionRepository.addSession(session);
         return session.getSessionId();
     }
@@ -655,10 +657,8 @@ public class ApplicationRepository implements com.yahoo.config.provision.Deploye
         Tenant tenant = tenantRepository.getTenant(applicationId.tenant());
         tenant.getApplicationRepo().createApplication(applicationId);
         Optional<Long> activeSessionId = tenant.getApplicationRepo().activeSessionOf(applicationId);
-        LocalSession session = tenant.getSessionRepository().createSession(applicationDirectory,
-                                                                           applicationId,
-                                                                           timeoutBudget,
-                                                                           activeSessionId);
+        LocalSession session = tenant.getSessionFactory().createSession(applicationDirectory, applicationId,
+                                                                        timeoutBudget, activeSessionId);
         tenant.getSessionRepository().addSession(session);
         return session.getSessionId();
     }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionFactory.java b/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionFactory.java
new file mode 100644
index 00000000000..8aba9fa465d
--- /dev/null
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionFactory.java
@@ -0,0 +1,280 @@
+// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.config.server.session;
+
+import com.yahoo.config.FileReference;
+import com.yahoo.config.application.api.ApplicationPackage;
+import com.yahoo.config.application.api.DeployLogger;
+import com.yahoo.config.model.application.provider.DeployData;
+import com.yahoo.config.model.application.provider.FilesApplicationPackage;
+import com.yahoo.config.provision.ApplicationId;
+import com.yahoo.config.provision.NodeFlavors;
+import com.yahoo.config.provision.TenantName;
+import com.yahoo.io.IOUtils;
+import com.yahoo.path.Path;
+import com.yahoo.vespa.config.server.GlobalComponentRegistry;
+import com.yahoo.vespa.config.server.TimeoutBudget;
+import com.yahoo.vespa.config.server.application.TenantApplications;
+import com.yahoo.vespa.config.server.deploy.TenantFileSystemDirs;
+import com.yahoo.vespa.config.server.filedistribution.FileDirectory;
+import com.yahoo.vespa.config.server.host.HostValidator;
+import com.yahoo.vespa.config.server.tenant.TenantRepository;
+import com.yahoo.vespa.config.server.zookeeper.ConfigCurator;
+import com.yahoo.vespa.config.server.zookeeper.SessionCounter;
+import com.yahoo.vespa.curator.Curator;
+import com.yahoo.vespa.defaults.Defaults;
+import com.yahoo.vespa.flags.BooleanFlag;
+import com.yahoo.vespa.flags.Flags;
+
+import java.io.File;
+import java.io.IOException;
+import java.time.Clock;
+import java.util.List;
+import java.util.Optional;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * Serves as the factory of sessions. Takes care of copying files to the correct folder and initializing the
+ * session state. There is one SessionFactory per tenant.
+ *
+ * @author Ulf Lilleengen
+ */
+public class SessionFactory {
+
+    private static final Logger log = Logger.getLogger(SessionFactory.class.getName());
+    private static final long nonExistingActiveSession = 0;
+
+    private final SessionPreparer sessionPreparer;
+    private final Curator curator;
+    private final ConfigCurator configCurator;
+    private final TenantApplications applicationRepo;
+    private final Path sessionsPath;
+    private final GlobalComponentRegistry componentRegistry;
+    private final HostValidator<ApplicationId> hostRegistry;
+    private final TenantName tenant;
+    private final String serverId;
+    private final Optional<NodeFlavors> nodeFlavors;
+    private final Clock clock;
+    private final BooleanFlag distributeApplicationPackage;
+
+    public SessionFactory(GlobalComponentRegistry globalComponentRegistry,
+                          TenantApplications applicationRepo,
+                          HostValidator<ApplicationId> hostRegistry,
+                          TenantName tenant) {
+        this.hostRegistry = hostRegistry;
+        this.tenant = tenant;
+        this.sessionPreparer = globalComponentRegistry.getSessionPreparer();
+        this.curator = globalComponentRegistry.getCurator();
+        this.configCurator = globalComponentRegistry.getConfigCurator();
+        this.sessionsPath = TenantRepository.getSessionsPath(tenant);
+        this.applicationRepo = applicationRepo;
+        this.componentRegistry = globalComponentRegistry;
+        this.serverId = globalComponentRegistry.getConfigserverConfig().serverId();
+        this.nodeFlavors = globalComponentRegistry.getZone().nodeFlavors();
+        this.clock = globalComponentRegistry.getClock();
+        this.distributeApplicationPackage = Flags.CONFIGSERVER_DISTRIBUTE_APPLICATION_PACKAGE
+                .bindTo(globalComponentRegistry.getFlagSource());
+    }
+
+    /**
+     * Creates a new deployment session from an application package.
+     *
+     * @param applicationDirectory a File pointing to an application.
+     * @param applicationId application id for this new session.
+     * @param timeoutBudget Timeout for creating session and waiting for other servers.
+     * @return a new session
+     */
+    public LocalSession createSession(File applicationDirectory, ApplicationId applicationId,
+                                      TimeoutBudget timeoutBudget, Optional<Long> activeSessionId) {
+        return create(applicationDirectory, applicationId, activeSessionId.orElse(nonExistingActiveSession), false, timeoutBudget);
+    }
+
+    public RemoteSession createRemoteSession(long sessionId) {
+        SessionZooKeeperClient sessionZKClient = createSessionZooKeeperClient(getSessionPath(sessionId));
+        return new RemoteSession(tenant, sessionId, componentRegistry, sessionZKClient);
+    }
+
+    private void ensureSessionPathDoesNotExist(long sessionId) {
+        Path sessionPath = getSessionPath(sessionId);
+        if (configCurator.exists(sessionPath.getAbsolute())) {
+            throw new IllegalArgumentException("Path " + sessionPath.getAbsolute() + " already exists in ZooKeeper");
+        }
+    }
+
+    private ApplicationPackage createApplication(File userDir,
+                                                 File configApplicationDir,
+                                                 ApplicationId applicationId,
+                                                 long sessionId,
+                                                 long currentlyActiveSessionId,
+                                                 boolean internalRedeploy) {
+        long deployTimestamp = System.currentTimeMillis();
+        String user = System.getenv("USER");
+        if (user == null) {
+            user = "unknown";
+        }
+        DeployData deployData = new DeployData(user, userDir.getAbsolutePath(), applicationId, deployTimestamp, internalRedeploy, sessionId, currentlyActiveSessionId);
+        return FilesApplicationPackage.fromFileWithDeployData(configApplicationDir, deployData);
+    }
+
+    private LocalSession createSessionFromApplication(ApplicationPackage applicationPackage,
+                                                      long sessionId,
+                                                      TimeoutBudget timeoutBudget,
+                                                      Clock clock) {
+        log.log(Level.FINE, TenantRepository.logPre(tenant) + "Creating session " + sessionId + " in ZooKeeper");
+        SessionZooKeeperClient sessionZKClient = createSessionZooKeeperClient(getSessionPath(sessionId));
+        sessionZKClient.createNewSession(clock.instant());
+        Curator.CompletionWaiter waiter = sessionZKClient.getUploadWaiter();
+        LocalSession session = new LocalSession(tenant, sessionId, sessionPreparer, applicationPackage, sessionZKClient,
+                                                getSessionAppDir(sessionId), applicationRepo, hostRegistry);
+        waiter.awaitCompletion(timeoutBudget.timeLeft());
+        return session;
+    }
+
+    /**
+     * Creates a new deployment session from an already existing session.
+     *
+     * @param existingSession the session to use as base
+     * @param logger a deploy logger where the deploy log will be written.
+     * @param internalRedeploy whether this session is for a system internal redeploy — not an application package change
+     * @param timeoutBudget timeout for creating session and waiting for other servers.
+     * @return a new session
+     */
+    public LocalSession createSessionFromExisting(Session existingSession,
+                                                  DeployLogger logger,
+                                                  boolean internalRedeploy,
+                                                  TimeoutBudget timeoutBudget) {
+        File existingApp = getSessionAppDir(existingSession.getSessionId());
+        ApplicationId existingApplicationId = existingSession.getApplicationId();
+
+        long activeSessionId = getActiveSessionId(existingApplicationId);
+        logger.log(Level.FINE, "Create new session for application id '" + existingApplicationId + "' from existing active session " + activeSessionId);
+        LocalSession session = create(existingApp, existingApplicationId, activeSessionId, internalRedeploy, timeoutBudget);
+        // Note: Needs to be kept in sync with calls in SessionPreparer.writeStateToZooKeeper()
+        session.setApplicationId(existingApplicationId);
+        if (distributeApplicationPackage.value() && existingSession.getApplicationPackageReference() != null) {
+            session.setApplicationPackageReference(existingSession.getApplicationPackageReference());
+        }
+        session.setVespaVersion(existingSession.getVespaVersion());
+        session.setDockerImageRepository(existingSession.getDockerImageRepository());
+        session.setAthenzDomain(existingSession.getAthenzDomain());
+        return session;
+    }
+
+    private LocalSession create(File applicationFile, ApplicationId applicationId, long currentlyActiveSessionId,
+                                boolean internalRedeploy, TimeoutBudget timeoutBudget) {
+        long sessionId = getNextSessionId();
+        try {
+            ensureSessionPathDoesNotExist(sessionId);
+            ApplicationPackage app = createApplicationPackage(applicationFile, applicationId,
+                                                              sessionId, currentlyActiveSessionId, internalRedeploy);
+            return createSessionFromApplication(app, sessionId, timeoutBudget, clock);
+        } catch (Exception e) {
+            throw new RuntimeException("Error creating session " + sessionId, e);
+        }
+    }
+
+    /**
+     * This method is used when creating a session based on a remote session and the distributed application package
+     * It does not wait for session being created on other servers
+     */
+    private LocalSession createLocalSession(File applicationFile, ApplicationId applicationId,
+                                            long sessionId, long currentlyActiveSessionId) {
+        try {
+            ApplicationPackage applicationPackage = createApplicationPackage(applicationFile, applicationId,
+                                                                             sessionId, currentlyActiveSessionId, false);
+            SessionZooKeeperClient sessionZooKeeperClient = createSessionZooKeeperClient(getSessionPath(sessionId));
+            return new LocalSession(tenant, sessionId, sessionPreparer, applicationPackage, sessionZooKeeperClient,
+                                    getSessionAppDir(sessionId), applicationRepo, hostRegistry);
+        } catch (Exception e) {
+            throw new RuntimeException("Error creating session " + sessionId, e);
+        }
+    }
+
+    private ApplicationPackage createApplicationPackage(File applicationFile, ApplicationId applicationId,
+                                                        long sessionId, long currentlyActiveSessionId,
+                                                        boolean internalRedeploy) throws IOException {
+        File userApplicationDir = getSessionAppDir(sessionId);
+        IOUtils.copyDirectory(applicationFile, userApplicationDir);
+        ApplicationPackage applicationPackage = createApplication(applicationFile,
+                                                                  userApplicationDir,
+                                                                  applicationId,
+                                                                  sessionId,
+                                                                  currentlyActiveSessionId,
+                                                                  internalRedeploy);
+        applicationPackage.writeMetaData();
+        return applicationPackage;
+    }
+
+    /**
+     * Returns a new session instance for the given session id.
+     */
+    LocalSession createSessionFromId(long sessionId) {
+        File sessionDir = getAndValidateExistingSessionAppDir(sessionId);
+        ApplicationPackage applicationPackage = FilesApplicationPackage.fromFile(sessionDir);
+        Path sessionIdPath = sessionsPath.append(String.valueOf(sessionId));
+        SessionZooKeeperClient sessionZKClient = createSessionZooKeeperClient(sessionIdPath);
+        return new LocalSession(tenant, sessionId, sessionPreparer, applicationPackage, sessionZKClient,
+                                getSessionAppDir(sessionId), applicationRepo, hostRegistry);
+    }
+
+    /**
+     * Returns a new session instance for the given session id.
+     */
+    LocalSession createLocalSessionUsingDistributedApplicationPackage(long sessionId) {
+        if (applicationRepo.hasLocalSession(sessionId)) {
+            log.log(Level.FINE, "Local session for session id " + sessionId + " already exists");
+            return createSessionFromId(sessionId);
+        }
+
+        log.log(Level.INFO, "Creating local session for session id " + sessionId);
+        SessionZooKeeperClient sessionZKClient = createSessionZooKeeperClient(getSessionPath(sessionId));
+        FileReference fileReference = sessionZKClient.readApplicationPackageReference();
+        log.log(Level.FINE, "File reference for session id " + sessionId + ": " + fileReference);
+        if (fileReference != null) {
+            File rootDir = new File(Defaults.getDefaults().underVespaHome(componentRegistry.getConfigserverConfig().fileReferencesDir()));
+            File sessionDir = new FileDirectory(rootDir).getFile(fileReference);
+            if (!sessionDir.exists())
+                throw new RuntimeException("File reference for session " + sessionId + " not found (" + sessionDir.getAbsolutePath() + ")");
+            ApplicationId applicationId = sessionZKClient.readApplicationId();
+            return createLocalSession(sessionDir,
+                                      applicationId,
+                                      sessionId,
+                                      applicationRepo.activeSessionOf(applicationId).orElse(nonExistingActiveSession));
+        }
+        return null;
+    }
+
+    // Return Optional instead of faking it with nonExistingActiveSession
+    private long getActiveSessionId(ApplicationId applicationId) {
+        List<ApplicationId> applicationIds = applicationRepo.activeApplications();
+        if (applicationIds.contains(applicationId)) {
+            return applicationRepo.requireActiveSessionOf(applicationId);
+        }
+        return nonExistingActiveSession;
+    }
+
+    private long getNextSessionId() {
+        return new SessionCounter(componentRegistry.getConfigCurator(), tenant).nextSessionId();
+    }
+
+    private Path getSessionPath(long sessionId) {
+        return sessionsPath.append(String.valueOf(sessionId));
+    }
+
+    private SessionZooKeeperClient createSessionZooKeeperClient(Path sessionPath) {
+        return new SessionZooKeeperClient(curator, configCurator, sessionPath, serverId, nodeFlavors);
+    }
+
+    private File getAndValidateExistingSessionAppDir(long sessionId) {
+        File appDir = getSessionAppDir(sessionId);
+        if (!appDir.exists() || !appDir.isDirectory()) {
+            throw new IllegalArgumentException("Unable to find correct application directory for session " + sessionId);
+        }
+        return appDir;
+    }
+
+    private File getSessionAppDir(long sessionId) {
+        return new TenantFileSystemDirs(componentRegistry.getConfigServerDB(), tenant).getUserApplicationDir(sessionId);
+    }
+
+}
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionRepository.java b/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionRepository.java
index c0d09cfba30..9fe725453f4 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionRepository.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionRepository.java
@@ -3,31 +3,19 @@ package com.yahoo.vespa.config.server.session;
 
 import com.google.common.collect.HashMultiset;
 import com.google.common.collect.Multiset;
-import com.yahoo.config.FileReference;
-import com.yahoo.config.application.api.ApplicationPackage;
-import com.yahoo.config.application.api.DeployLogger;
-import com.yahoo.config.model.application.provider.DeployData;
-import com.yahoo.config.model.application.provider.FilesApplicationPackage;
 import com.yahoo.config.provision.ApplicationId;
-import com.yahoo.config.provision.NodeFlavors;
 import com.yahoo.config.provision.TenantName;
-import com.yahoo.io.IOUtils;
 import com.yahoo.path.Path;
 import com.yahoo.transaction.NestedTransaction;
 import com.yahoo.vespa.config.server.GlobalComponentRegistry;
 import com.yahoo.vespa.config.server.ReloadHandler;
-import com.yahoo.vespa.config.server.TimeoutBudget;
 import com.yahoo.vespa.config.server.application.TenantApplications;
 import com.yahoo.vespa.config.server.deploy.TenantFileSystemDirs;
-import com.yahoo.vespa.config.server.filedistribution.FileDirectory;
-import com.yahoo.vespa.config.server.host.HostValidator;
 import com.yahoo.vespa.config.server.monitoring.MetricUpdater;
 import com.yahoo.vespa.config.server.monitoring.Metrics;
 import com.yahoo.vespa.config.server.tenant.TenantRepository;
 import com.yahoo.vespa.config.server.zookeeper.ConfigCurator;
-import com.yahoo.vespa.config.server.zookeeper.SessionCounter;
 import com.yahoo.vespa.curator.Curator;
-import com.yahoo.vespa.defaults.Defaults;
 import com.yahoo.vespa.flags.BooleanFlag;
 import com.yahoo.vespa.flags.FlagSource;
 import com.yahoo.vespa.flags.Flags;
@@ -37,7 +25,6 @@ import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
 
 import java.io.File;
 import java.io.FilenameFilter;
-import java.io.IOException;
 import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
@@ -46,7 +33,6 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.concurrent.Executor;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -65,9 +51,9 @@ public class SessionRepository {
 
     private static final Logger log = Logger.getLogger(SessionRepository.class.getName());
     private static final FilenameFilter sessionApplicationsFilter = (dir, name) -> name.matches("\\d+");
-    private static final long nonExistingActiveSession = 0;
 
     private final SessionCache<LocalSession> localSessionCache;
+
     private final SessionCache<RemoteSession> remoteSessionCache = new SessionCache<>();
     private final Map<Long, LocalSessionStateWatcher> localSessionStateWatchers = new HashMap<>();
     private final Map<Long, RemoteSessionStateWatcher> remoteSessionStateWatchers = new HashMap<>();
@@ -81,36 +67,28 @@ public class SessionRepository {
     private final MetricUpdater metrics;
     private final Curator.DirectoryCache directoryCache;
     private final TenantApplications applicationRepo;
-    private final HostValidator<ApplicationId> hostRegistry;
-    private final SessionPreparer sessionPreparer;
     private final Path sessionsPath;
+    private final SessionFactory sessionFactory;
     private final TenantName tenantName;
-    private final GlobalComponentRegistry componentRegistry;
-
-    public SessionRepository(TenantName tenantName,
-                             GlobalComponentRegistry componentRegistry,
-                             TenantApplications applicationRepo,
-                             ReloadHandler reloadHandler,
-                             FlagSource flagSource,
-                             HostValidator<ApplicationId> hostRegistry,
-                             SessionPreparer sessionPreparer) {
+
+    public SessionRepository(TenantName tenantName, GlobalComponentRegistry componentRegistry,
+                             SessionFactory sessionFactory, TenantApplications applicationRepo,
+                             ReloadHandler reloadHandler, FlagSource flagSource) {
         this.tenantName = tenantName;
-        this.componentRegistry = componentRegistry;
-        this.sessionsPath = TenantRepository.getSessionsPath(tenantName);
         localSessionCache = new SessionCache<>();
         this.clock = componentRegistry.getClock();
         this.curator = componentRegistry.getCurator();
         this.sessionLifetime = Duration.ofSeconds(componentRegistry.getConfigserverConfig().sessionLifetime());
         this.zkWatcherExecutor = command -> componentRegistry.getZkWatcherExecutor().execute(tenantName, command);
         this.tenantFileSystemDirs = new TenantFileSystemDirs(componentRegistry.getConfigServerDB(), tenantName);
+        this.sessionFactory = sessionFactory;
         this.applicationRepo = applicationRepo;
-        this.hostRegistry = hostRegistry;
-        this.sessionPreparer = sessionPreparer;
+        loadLocalSessions(sessionFactory);
+
         this.distributeApplicationPackage = Flags.CONFIGSERVER_DISTRIBUTE_APPLICATION_PACKAGE.bindTo(flagSource);
         this.reloadHandler = reloadHandler;
+        this.sessionsPath = TenantRepository.getSessionsPath(tenantName);
         this.metrics = componentRegistry.getMetrics().getOrCreateMetricUpdater(Metrics.createDimensions(tenantName));
-
-        loadLocalSessions();
         initializeRemoteSessions();
         this.directoryCache = curator.createDirectoryCache(sessionsPath.getAbsolute(), false, false, componentRegistry.getZkCacheExecutor());
         this.directoryCache.addListener(this::childEvent);
@@ -135,14 +113,14 @@ public class SessionRepository {
         return localSessionCache.getSessions();
     }
 
-    private void loadLocalSessions() {
+    private void loadLocalSessions(SessionFactory sessionFactory) {
         File[] sessions = tenantFileSystemDirs.sessionsPath().listFiles(sessionApplicationsFilter);
         if (sessions == null) {
             return;
         }
         for (File session : sessions) {
             try {
-                addSession(createSessionFromId(Long.parseLong(session.getName())));
+                addSession(sessionFactory.createSessionFromId(Long.parseLong(session.getName())));
             } catch (IllegalArgumentException e) {
                 log.log(Level.WARNING, "Could not load session '" +
                         session.getAbsolutePath() + "':" + e.getMessage() + ", skipping it.");
@@ -291,7 +269,7 @@ public class SessionRepository {
      */
     private void sessionAdded(long sessionId) {
         log.log(Level.FINE, () -> "Adding session to SessionRepository: " + sessionId);
-        RemoteSession session = createRemoteSession(sessionId);
+        RemoteSession session = sessionFactory.createRemoteSession(sessionId);
         Path sessionPath = sessionsPath.append(String.valueOf(sessionId));
         Curator.FileCache fileCache = curator.createFileCache(sessionPath.append(ConfigCurator.SESSIONSTATE_ZK_SUBPATH).getAbsolute(), false);
         fileCache.addListener(this::nodeChanged);
@@ -299,7 +277,7 @@ public class SessionRepository {
         addRemoteSession(session);
         remoteSessionStateWatchers.put(sessionId, new RemoteSessionStateWatcher(fileCache, reloadHandler, session, metrics, zkWatcherExecutor));
         if (distributeApplicationPackage.value())
-            createLocalSessionUsingDistributedApplicationPackage(sessionId);
+            sessionFactory.createLocalSessionUsingDistributedApplicationPackage(sessionId);
     }
 
     private void sessionRemoved(long sessionId) {
@@ -361,209 +339,6 @@ public class SessionRepository {
         }
     }
 
-    /**
-     * Creates a new deployment session from an application package.
-     *
-     * @param applicationDirectory a File pointing to an application.
-     * @param applicationId application id for this new session.
-     * @param timeoutBudget Timeout for creating session and waiting for other servers.
-     * @return a new session
-     */
-    public LocalSession createSession(File applicationDirectory, ApplicationId applicationId,
-                                      TimeoutBudget timeoutBudget, Optional<Long> activeSessionId) {
-        return create(applicationDirectory, applicationId, activeSessionId.orElse(nonExistingActiveSession), false, timeoutBudget);
-    }
-
-    public RemoteSession createRemoteSession(long sessionId) {
-        SessionZooKeeperClient sessionZKClient = createSessionZooKeeperClient(getSessionPath(sessionId));
-        return new RemoteSession(tenantName, sessionId, componentRegistry, sessionZKClient);
-    }
-
-    private void ensureSessionPathDoesNotExist(long sessionId) {
-        Path sessionPath = getSessionPath(sessionId);
-        if (componentRegistry.getConfigCurator().exists(sessionPath.getAbsolute())) {
-            throw new IllegalArgumentException("Path " + sessionPath.getAbsolute() + " already exists in ZooKeeper");
-        }
-    }
-
-    private ApplicationPackage createApplication(File userDir,
-                                                 File configApplicationDir,
-                                                 ApplicationId applicationId,
-                                                 long sessionId,
-                                                 long currentlyActiveSessionId,
-                                                 boolean internalRedeploy) {
-        long deployTimestamp = System.currentTimeMillis();
-        String user = System.getenv("USER");
-        if (user == null) {
-            user = "unknown";
-        }
-        DeployData deployData = new DeployData(user, userDir.getAbsolutePath(), applicationId, deployTimestamp, internalRedeploy, sessionId, currentlyActiveSessionId);
-        return FilesApplicationPackage.fromFileWithDeployData(configApplicationDir, deployData);
-    }
-
-    private LocalSession createSessionFromApplication(ApplicationPackage applicationPackage,
-                                                      long sessionId,
-                                                      TimeoutBudget timeoutBudget,
-                                                      Clock clock) {
-        log.log(Level.FINE, TenantRepository.logPre(tenantName) + "Creating session " + sessionId + " in ZooKeeper");
-        SessionZooKeeperClient sessionZKClient = createSessionZooKeeperClient(getSessionPath(sessionId));
-        sessionZKClient.createNewSession(clock.instant());
-        Curator.CompletionWaiter waiter = sessionZKClient.getUploadWaiter();
-        LocalSession session = new LocalSession(tenantName, sessionId, sessionPreparer, applicationPackage, sessionZKClient,
-                                                getSessionAppDir(sessionId), applicationRepo, hostRegistry);
-        waiter.awaitCompletion(timeoutBudget.timeLeft());
-        return session;
-    }
-
-    /**
-     * Creates a new deployment session from an already existing session.
-     *
-     * @param existingSession the session to use as base
-     * @param logger a deploy logger where the deploy log will be written.
-     * @param internalRedeploy whether this session is for a system internal redeploy — not an application package change
-     * @param timeoutBudget timeout for creating session and waiting for other servers.
-     * @return a new session
-     */
-    public LocalSession createSessionFromExisting(Session existingSession,
-                                                  DeployLogger logger,
-                                                  boolean internalRedeploy,
-                                                  TimeoutBudget timeoutBudget) {
-        File existingApp = getSessionAppDir(existingSession.getSessionId());
-        ApplicationId existingApplicationId = existingSession.getApplicationId();
-
-        long activeSessionId = getActiveSessionId(existingApplicationId);
-        logger.log(Level.FINE, "Create new session for application id '" + existingApplicationId + "' from existing active session " + activeSessionId);
-        LocalSession session = create(existingApp, existingApplicationId, activeSessionId, internalRedeploy, timeoutBudget);
-        // Note: Needs to be kept in sync with calls in SessionPreparer.writeStateToZooKeeper()
-        session.setApplicationId(existingApplicationId);
-        if (distributeApplicationPackage.value() && existingSession.getApplicationPackageReference() != null) {
-            session.setApplicationPackageReference(existingSession.getApplicationPackageReference());
-        }
-        session.setVespaVersion(existingSession.getVespaVersion());
-        session.setDockerImageRepository(existingSession.getDockerImageRepository());
-        session.setAthenzDomain(existingSession.getAthenzDomain());
-        return session;
-    }
-
-    private LocalSession create(File applicationFile, ApplicationId applicationId, long currentlyActiveSessionId,
-                                boolean internalRedeploy, TimeoutBudget timeoutBudget) {
-        long sessionId = getNextSessionId();
-        try {
-            ensureSessionPathDoesNotExist(sessionId);
-            ApplicationPackage app = createApplicationPackage(applicationFile, applicationId,
-                                                              sessionId, currentlyActiveSessionId, internalRedeploy);
-            return createSessionFromApplication(app, sessionId, timeoutBudget, clock);
-        } catch (Exception e) {
-            throw new RuntimeException("Error creating session " + sessionId, e);
-        }
-    }
-
-    /**
-     * This method is used when creating a session based on a remote session and the distributed application package
-     * It does not wait for session being created on other servers
-     */
-    private LocalSession createLocalSession(File applicationFile, ApplicationId applicationId,
-                                            long sessionId, long currentlyActiveSessionId) {
-        try {
-            ApplicationPackage applicationPackage = createApplicationPackage(applicationFile, applicationId,
-                                                                             sessionId, currentlyActiveSessionId, false);
-            SessionZooKeeperClient sessionZooKeeperClient = createSessionZooKeeperClient(getSessionPath(sessionId));
-            return new LocalSession(tenantName, sessionId, sessionPreparer, applicationPackage, sessionZooKeeperClient,
-                                    getSessionAppDir(sessionId), applicationRepo, hostRegistry);
-        } catch (Exception e) {
-            throw new RuntimeException("Error creating session " + sessionId, e);
-        }
-    }
-
-    private ApplicationPackage createApplicationPackage(File applicationFile, ApplicationId applicationId,
-                                                        long sessionId, long currentlyActiveSessionId,
-                                                        boolean internalRedeploy) throws IOException {
-        File userApplicationDir = getSessionAppDir(sessionId);
-        IOUtils.copyDirectory(applicationFile, userApplicationDir);
-        ApplicationPackage applicationPackage = createApplication(applicationFile,
-                                                                  userApplicationDir,
-                                                                  applicationId,
-                                                                  sessionId,
-                                                                  currentlyActiveSessionId,
-                                                                  internalRedeploy);
-        applicationPackage.writeMetaData();
-        return applicationPackage;
-    }
-
-    /**
-     * Returns a new session instance for the given session id.
-     */
-    LocalSession createSessionFromId(long sessionId) {
-        File sessionDir = getAndValidateExistingSessionAppDir(sessionId);
-        ApplicationPackage applicationPackage = FilesApplicationPackage.fromFile(sessionDir);
-        Path sessionIdPath = sessionsPath.append(String.valueOf(sessionId));
-        SessionZooKeeperClient sessionZKClient = createSessionZooKeeperClient(sessionIdPath);
-        return new LocalSession(tenantName, sessionId, sessionPreparer, applicationPackage, sessionZKClient,
-                                getSessionAppDir(sessionId), applicationRepo, hostRegistry);
-    }
-
-    /**
-     * Returns a new session instance for the given session id.
-     */
-    LocalSession createLocalSessionUsingDistributedApplicationPackage(long sessionId) {
-        if (applicationRepo.hasLocalSession(sessionId)) {
-            log.log(Level.FINE, "Local session for session id " + sessionId + " already exists");
-            return createSessionFromId(sessionId);
-        }
-
-        log.log(Level.INFO, "Creating local session for session id " + sessionId);
-        SessionZooKeeperClient sessionZKClient = createSessionZooKeeperClient(getSessionPath(sessionId));
-        FileReference fileReference = sessionZKClient.readApplicationPackageReference();
-        log.log(Level.FINE, "File reference for session id " + sessionId + ": " + fileReference);
-        if (fileReference != null) {
-            File rootDir = new File(Defaults.getDefaults().underVespaHome(componentRegistry.getConfigserverConfig().fileReferencesDir()));
-            File sessionDir = new FileDirectory(rootDir).getFile(fileReference);
-            if (!sessionDir.exists())
-                throw new RuntimeException("File reference for session " + sessionId + " not found (" + sessionDir.getAbsolutePath() + ")");
-            ApplicationId applicationId = sessionZKClient.readApplicationId();
-            return createLocalSession(sessionDir,
-                                      applicationId,
-                                      sessionId,
-                                      applicationRepo.activeSessionOf(applicationId).orElse(nonExistingActiveSession));
-        }
-        return null;
-    }
-
-    // Return Optional instead of faking it with nonExistingActiveSession
-    private long getActiveSessionId(ApplicationId applicationId) {
-        List<ApplicationId> applicationIds = applicationRepo.activeApplications();
-        if (applicationIds.contains(applicationId)) {
-            return applicationRepo.requireActiveSessionOf(applicationId);
-        }
-        return nonExistingActiveSession;
-    }
-
-    private long getNextSessionId() {
-        return new SessionCounter(componentRegistry.getConfigCurator(), tenantName).nextSessionId();
-    }
-
-    private Path getSessionPath(long sessionId) {
-        return sessionsPath.append(String.valueOf(sessionId));
-    }
-
-    private SessionZooKeeperClient createSessionZooKeeperClient(Path sessionPath) {
-        String serverId = componentRegistry.getConfigserverConfig().serverId();
-        Optional<NodeFlavors> nodeFlavors = componentRegistry.getZone().nodeFlavors();
-        return new SessionZooKeeperClient(curator, componentRegistry.getConfigCurator(), sessionPath, serverId, nodeFlavors);
-    }
-
-    private File getAndValidateExistingSessionAppDir(long sessionId) {
-        File appDir = getSessionAppDir(sessionId);
-        if (!appDir.exists() || !appDir.isDirectory()) {
-            throw new IllegalArgumentException("Unable to find correct application directory for session " + sessionId);
-        }
-        return appDir;
-    }
-
-    private File getSessionAppDir(long sessionId) {
-        return new TenantFileSystemDirs(componentRegistry.getConfigServerDB(), tenantName).getUserApplicationDir(sessionId);
-    }
-
     @Override
     public String toString() {
         return getSessions().toString();
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/tenant/Tenant.java b/configserver/src/main/java/com/yahoo/vespa/config/server/tenant/Tenant.java
index 06cfe704046..097c3146b81 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/tenant/Tenant.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/tenant/Tenant.java
@@ -7,6 +7,7 @@ import com.yahoo.vespa.config.server.ReloadHandler;
 import com.yahoo.vespa.config.server.RequestHandler;
 import com.yahoo.vespa.config.server.application.TenantApplications;
 import com.yahoo.vespa.config.server.session.SessionRepository;
+import com.yahoo.vespa.config.server.session.SessionFactory;
 import com.yahoo.vespa.curator.Curator;
 import org.apache.zookeeper.data.Stat;
 
@@ -27,6 +28,7 @@ public class Tenant implements TenantHandlerProvider {
 
     private final TenantName name;
     private final Path path;
+    private final SessionFactory sessionFactory;
     private final SessionRepository sessionRepository;
     private final TenantApplications applicationRepo;
     private final RequestHandler requestHandler;
@@ -34,6 +36,7 @@ public class Tenant implements TenantHandlerProvider {
     private final Curator curator;
 
     Tenant(TenantName name,
+           SessionFactory sessionFactory,
            SessionRepository sessionRepository,
            RequestHandler requestHandler,
            ReloadHandler reloadHandler,
@@ -43,6 +46,7 @@ public class Tenant implements TenantHandlerProvider {
         this.path = TenantRepository.getTenantPath(name);
         this.requestHandler = requestHandler;
         this.reloadHandler = reloadHandler;
+        this.sessionFactory = sessionFactory;
         this.sessionRepository = sessionRepository;
         this.applicationRepo = applicationRepo;
         this.curator = curator;
@@ -78,7 +82,13 @@ public class Tenant implements TenantHandlerProvider {
         return path;
     }
 
-    public SessionRepository getSessionRepository() { return sessionRepository; }
+    public SessionFactory getSessionFactory() {
+        return sessionFactory;
+    }
+
+    public SessionRepository getSessionRepository() {
+        return sessionRepository;
+    }
 
     @Override
     public String toString() {
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/tenant/TenantRepository.java b/configserver/src/main/java/com/yahoo/vespa/config/server/tenant/TenantRepository.java
index 35e6a58af9c..caf9982e034 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/tenant/TenantRepository.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/tenant/TenantRepository.java
@@ -15,6 +15,7 @@ import com.yahoo.vespa.config.server.application.TenantApplications;
 import com.yahoo.vespa.config.server.deploy.TenantFileSystemDirs;
 import com.yahoo.vespa.config.server.monitoring.MetricUpdater;
 import com.yahoo.vespa.config.server.session.SessionRepository;
+import com.yahoo.vespa.config.server.session.SessionFactory;
 import com.yahoo.vespa.curator.Curator;
 import org.apache.curator.framework.CuratorFramework;
 import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
@@ -221,13 +222,12 @@ public class TenantRepository {
             requestHandler = applicationRepo;
         if (reloadHandler == null)
             reloadHandler = applicationRepo;
-        SessionRepository sessionRepository = new SessionRepository(tenantName, componentRegistry,
+        SessionFactory sessionFactory = new SessionFactory(componentRegistry, applicationRepo, applicationRepo, tenantName);
+        SessionRepository sessionRepository = new SessionRepository(tenantName, componentRegistry, sessionFactory,
                                                                     applicationRepo, reloadHandler,
-                                                                    componentRegistry.getFlagSource(),
-                                                                    componentRegistry.getHostRegistries().createApplicationHostRegistry(tenantName),
-                                                                    componentRegistry.getSessionPreparer());
+                                                                    componentRegistry.getFlagSource());
         log.log(Level.INFO, "Creating tenant '" + tenantName + "'");
-        Tenant tenant = new Tenant(tenantName, sessionRepository, requestHandler,
+        Tenant tenant = new Tenant(tenantName, sessionFactory, sessionRepository, requestHandler,
                                    reloadHandler, applicationRepo, componentRegistry.getCurator());
         notifyNewTenant(tenant);
         tenants.putIfAbsent(tenantName, tenant);
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/session/SessionRepositoryTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/session/SessionRepositoryTest.java
index f73fb053649..3c1404b5048 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/session/SessionRepositoryTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/session/SessionRepositoryTest.java
@@ -9,6 +9,7 @@ import com.yahoo.text.Utf8;
 import com.yahoo.vespa.config.server.GlobalComponentRegistry;
 import com.yahoo.vespa.config.server.TestComponentRegistry;
 import com.yahoo.vespa.config.server.application.TenantApplications;
+import com.yahoo.vespa.config.server.host.HostRegistry;
 import com.yahoo.vespa.config.server.http.SessionHandlerTest;
 import com.yahoo.vespa.config.server.tenant.Tenant;
 import com.yahoo.vespa.config.server.tenant.TenantRepository;
@@ -74,9 +75,12 @@ public class SessionRepositoryTest {
                 .build();
         tenantRepository = new TenantRepository(globalComponentRegistry, false);
         TenantApplications applicationRepo = TenantApplications.create(globalComponentRegistry, tenantName);
-        sessionRepository = new SessionRepository(tenantName, globalComponentRegistry,
-                                                  applicationRepo, applicationRepo, new InMemoryFlagSource(),
-                                                  applicationRepo, globalComponentRegistry.getSessionPreparer());
+        SessionFactory sessionFactory = new SessionFactory(globalComponentRegistry,
+                                                           applicationRepo,
+                                                           new HostRegistry<>(),
+                                                           tenantName);
+        sessionRepository = new SessionRepository(tenantName, globalComponentRegistry, sessionFactory,
+                                                  applicationRepo, applicationRepo, new InMemoryFlagSource());
     }
 
     @Test