Add maintainer for downloading missing application packages.

- Not yet enabled

3 files changed, 89 insertions, 2 deletions

diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileServer.java b/configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileServer.java
index 805ee2bef95..1e7f9fd69e7 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileServer.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileServer.java
@@ -199,8 +199,9 @@ public class FileServer {
         downloader.close();
     }
 
+    // TODO: move to e.g. a util class
     // Connection pool with all config servers except this one (might be an empty pool if there is only one config server)
-    private static ConnectionPool createConnectionPool(ConfigserverConfig configserverConfig) {
+    public static ConnectionPool createConnectionPool(ConfigserverConfig configserverConfig) {
         List<String> configServers = ConfigServerSpec.fromConfig(configserverConfig)
                 .stream()
                 .filter(spec -> !spec.getHostName().equals(HostName.getLocalhost()))
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/maintenance/ApplicationPackageMaintainer.java b/configserver/src/main/java/com/yahoo/vespa/config/server/maintenance/ApplicationPackageMaintainer.java
new file mode 100644
index 00000000000..2a00a175fd8
--- /dev/null
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/maintenance/ApplicationPackageMaintainer.java
@@ -0,0 +1,86 @@
+package com.yahoo.vespa.config.server.maintenance;
+
+import com.yahoo.cloud.config.ConfigserverConfig;
+import com.yahoo.config.FileReference;
+import com.yahoo.vespa.config.server.ApplicationRepository;
+import com.yahoo.vespa.config.server.filedistribution.FileServer;
+import com.yahoo.vespa.config.server.session.RemoteSession;
+import com.yahoo.vespa.curator.Curator;
+import com.yahoo.vespa.defaults.Defaults;
+import com.yahoo.vespa.filedistribution.FileDownloader;
+import com.yahoo.vespa.flags.BooleanFlag;
+import com.yahoo.vespa.flags.FlagSource;
+import com.yahoo.vespa.flags.Flags;
+
+import java.io.File;
+import java.time.Duration;
+import java.util.Set;
+import java.util.logging.Logger;
+
+import static com.yahoo.vespa.config.server.ApplicationRepository.getFileReferencesOnDisk;
+
+/**
+ * Verifies that all active sessions has an application package on local disk.
+ * If not, the package is downloaded with file distribution. This can happen e.g.
+ * if a configserver is down when the application is deployed.
+ *
+ * @author gjoranv
+ */
+public class ApplicationPackageMaintainer extends ConfigServerMaintainer {
+    private static final Logger log = Logger.getLogger(ApplicationPackageMaintainer.class.getName());
+
+    private final ApplicationRepository applicationRepository;
+    private final ConfigserverConfig configserverConfig;
+    private final File downloadDirectory;
+    private final BooleanFlag distributeApplicationPackage;
+
+    public ApplicationPackageMaintainer(ApplicationRepository applicationRepository,
+                                        Curator curator,
+                                        Duration interval,
+                                        ConfigserverConfig configserverConfig,
+                                        FlagSource flagSource) {
+        super(applicationRepository, curator, interval, interval);
+        this.applicationRepository = applicationRepository;
+        this.configserverConfig = configserverConfig;
+
+        distributeApplicationPackage = Flags.CONFIGSERVER_DISTRIBUTE_APPLICATION_PACKAGE.bindTo(flagSource);
+        downloadDirectory = new File(Defaults.getDefaults().underVespaHome(configserverConfig.fileReferencesDir()));
+        if (distributeApplicationPackage.value()) assertDownloadDirectoryIsDefault(downloadDirectory);
+    }
+
+    @Override
+    protected void maintain() {
+        if (! distributeApplicationPackage.value()) return;
+
+        var fileDownloader =  new FileDownloader(FileServer.createConnectionPool(configserverConfig));
+        try {
+            for (var applicationId : applicationRepository.listApplications()) {
+                RemoteSession session = applicationRepository.getActiveSession(applicationId);
+                FileReference applicationPackage = session.getApplicationPackageReference();
+
+                if (applicationPackage != null && missingOnDisk(applicationPackage)) {
+                    log.fine(() -> "Downloading missing application package for application " + applicationId + " - session " + session.getSessionId());
+
+                    if (fileDownloader.getFile(applicationPackage).isEmpty()) {
+                        log.warning("Failed to download application package for application " + applicationId + " - session " + session.getSessionId());
+                    }
+                }
+            }
+        } finally {
+            fileDownloader.close();
+        }
+    }
+
+    private boolean missingOnDisk(FileReference applicationPackageReference) {
+        Set<String> fileReferencesOnDisk = getFileReferencesOnDisk(downloadDirectory);
+        return ! fileReferencesOnDisk.contains(applicationPackageReference.value());
+    }
+
+    // Required to use FileDownloader because it has no public ctor that takes a directory.
+    private static void assertDownloadDirectoryIsDefault(File fileReferencesDir) {
+        if (fileReferencesDir != FileDownloader.defaultDownloadDirectory) throw new IllegalArgumentException(
+                "Files must be downloaded to the default download directory ("
+                        + FileDownloader.defaultDownloadDirectory +  "), not " + fileReferencesDir);
+    }
+
+}
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/session/Session.java b/configserver/src/main/java/com/yahoo/vespa/config/server/session/Session.java
index 8b078f152f3..c553133ba12 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/session/Session.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/session/Session.java
@@ -107,7 +107,7 @@ public abstract class Session implements Comparable<Session>  {
 
     public ApplicationId getApplicationId() { return zooKeeperClient.readApplicationId(); }
 
-    FileReference getApplicationPackageReference() {return zooKeeperClient.readApplicationPackageReference(); }
+    public FileReference getApplicationPackageReference() {return zooKeeperClient.readApplicationPackageReference(); }
 
     public Optional<DockerImage> getDockerImageRepository() { return zooKeeperClient.readDockerImageRepository(); }