Add a dynamic configuration manager

service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerConfiguration.java

@@ -9,6 +9,7 @@ import io.dropwizard.Configuration;
 import io.dropwizard.client.JerseyClientConfiguration;
 import org.whispersystems.textsecuregcm.configuration.AccountDatabaseCrawlerConfiguration;
 import org.whispersystems.textsecuregcm.configuration.ApnConfiguration;
+import org.whispersystems.textsecuregcm.configuration.AppConfigConfiguration;
 import org.whispersystems.textsecuregcm.configuration.AwsAttachmentsConfiguration;
 import org.whispersystems.textsecuregcm.configuration.CdnConfiguration;
 import org.whispersystems.textsecuregcm.configuration.DatabaseConfiguration;
@@ -216,6 +217,11 @@ public class WhisperServerConfiguration extends Configuration {
   @JsonProperty
   private RemoteConfigConfiguration remoteConfig;
 
+  @Valid
+  @NotNull
+  @JsonProperty
+  private AppConfigConfiguration appConfig;
+
   private Map<String, String> transparentDataIndex = new HashMap<>();
 
   public RecaptchaConfiguration getRecaptchaConfiguration() {
@@ -371,4 +377,8 @@ public class WhisperServerConfiguration extends Configuration {
   public RemoteConfigConfiguration getRemoteConfigConfiguration() {
     return remoteConfig;
   }
+
+  public AppConfigConfiguration getAppConfig() {
+    return appConfig;
+  }
 }

service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java

@@ -116,6 +116,7 @@ import org.whispersystems.textsecuregcm.storage.ActiveUserCounter;
 import org.whispersystems.textsecuregcm.storage.DirectoryManager;
 import org.whispersystems.textsecuregcm.storage.DirectoryReconciler;
 import org.whispersystems.textsecuregcm.storage.DirectoryReconciliationClient;
+import org.whispersystems.textsecuregcm.storage.DynamicConfigurationManager;
 import org.whispersystems.textsecuregcm.storage.FaultTolerantDatabase;
 import org.whispersystems.textsecuregcm.storage.FeatureFlags;
 import org.whispersystems.textsecuregcm.storage.FeatureFlagsManager;
@@ -328,6 +329,8 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
     RateLimiters               rateLimiters               = new RateLimiters(config.getLimitsConfiguration(), cacheCluster);
     ProvisioningManager        provisioningManager        = new ProvisioningManager(pubSubManager);
 
+    DynamicConfigurationManager dynamicConfigurationManager = new DynamicConfigurationManager(config.getAppConfig().getApplication(), config.getAppConfig().getEnvironment(), config.getAppConfig().getConfigurationName());
+
     AccountAuthenticator                  accountAuthenticator                  = new AccountAuthenticator(accountsManager);
     DisabledPermittedAccountAuthenticator disabledPermittedAccountAuthenticator = new DisabledPermittedAccountAuthenticator(accountsManager);
 
@@ -373,6 +376,7 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
     environment.lifecycle().manage(messagePersister);
     environment.lifecycle().manage(clientPresenceManager);
     environment.lifecycle().manage(featureFlagsManager);
+    environment.lifecycle().manage(dynamicConfigurationManager);
 
     AWSCredentials         credentials               = new BasicAWSCredentials(config.getCdnConfiguration().getAccessKey(), config.getCdnConfiguration().getAccessSecret());
     AWSCredentialsProvider credentialsProvider       = new AWSStaticCredentialsProvider(credentials);

service/src/main/java/org/whispersystems/textsecuregcm/configuration/AppConfigConfiguration.java

@@ -0,0 +1,32 @@
+package org.whispersystems.textsecuregcm.configuration;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import javax.validation.constraints.NotEmpty;
+
+public class AppConfigConfiguration {
+
+  @JsonProperty
+  @NotEmpty
+  private String application;
+
+  @JsonProperty
+  @NotEmpty
+  private String environment;
+
+  @JsonProperty
+  @NotEmpty
+  private String configuration;
+
+  public String getApplication() {
+    return application;
+  }
+
+  public String getEnvironment() {
+    return environment;
+  }
+
+  public String getConfigurationName() {
+    return configuration;
+  }
+}

service/src/main/java/org/whispersystems/textsecuregcm/configuration/dynamic/DynamicConfiguration.java

@@ -0,0 +1,5 @@
+package org.whispersystems.textsecuregcm.configuration.dynamic;
+
+public class DynamicConfiguration {
+
+}

service/src/main/java/org/whispersystems/textsecuregcm/storage/DynamicConfigurationManager.java

@@ -0,0 +1,132 @@
+package org.whispersystems.textsecuregcm.storage;
+
+import com.amazonaws.ClientConfiguration;
+import com.amazonaws.services.appconfig.AmazonAppConfig;
+import com.amazonaws.services.appconfig.AmazonAppConfigClient;
+import com.amazonaws.services.appconfig.model.GetConfigurationRequest;
+import com.amazonaws.services.appconfig.model.GetConfigurationResult;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
+import com.google.common.annotations.VisibleForTesting;
+import io.dropwizard.lifecycle.Managed;
+import org.apache.commons.lang3.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.whispersystems.textsecuregcm.configuration.dynamic.DynamicConfiguration;
+import org.whispersystems.textsecuregcm.util.Util;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Optional;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+
+public class DynamicConfigurationManager implements Managed {
+
+  private final String          application;
+  private final String          environment;
+  private final String          configurationName;
+  private final String          clientId;
+  private final AmazonAppConfig appConfigClient;
+
+  private final ObjectMapper                            mapper           = new ObjectMapper(new YAMLFactory()).configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+  private final AtomicReference<DynamicConfiguration>   configuration    = new AtomicReference<>();
+  private final AtomicBoolean                           running          = new AtomicBoolean(true);
+  private final Logger                                  logger           = LoggerFactory.getLogger(DynamicConfigurationManager.class);
+
+  private GetConfigurationResult lastConfigResult;
+
+  private boolean initialized = false;
+
+  public DynamicConfigurationManager(String application, String environment, String configurationName) {
+    this(AmazonAppConfigClient.builder()
+                              .withClientConfiguration(new ClientConfiguration().withClientExecutionTimeout(10000).withRequestTimeout(10000))
+                              .build(),
+         application, environment, configurationName, UUID.randomUUID().toString());
+  }
+
+  @VisibleForTesting
+  public DynamicConfigurationManager(AmazonAppConfig appConfigClient, String application, String environment, String configurationName, String clientId) {
+    this.appConfigClient   = appConfigClient;
+    this.application       = application;
+    this.environment       = environment;
+    this.configurationName = configurationName;
+    this.clientId          = clientId;
+  }
+
+  public DynamicConfiguration getConfiguration() {
+    synchronized (this) {
+      while (!initialized) Util.wait(this);
+    }
+
+    return configuration.get();
+  }
+
+  @Override
+  public void start() {
+    configuration.set(retrieveInitialDynamicConfiguration());
+
+    synchronized (this) {
+      this.initialized = true;
+      this.notifyAll();
+    }
+
+    new Thread(() -> {
+      while (running.get()) {
+        try {
+          retrieveDynamicConfiguration().ifPresent(configuration::set);
+        } catch (Throwable t) {
+          logger.warn("Error retrieving dynamic configuration", t);
+        }
+
+        Util.sleep(5000);
+      }
+    }).start();
+  }
+
+  @Override
+  public void stop() {
+    running.set(false);
+  }
+
+  private Optional<DynamicConfiguration> retrieveDynamicConfiguration() throws JsonProcessingException {
+    final String previousVersion = lastConfigResult != null ? lastConfigResult.getConfigurationVersion() : null;
+
+    lastConfigResult = appConfigClient.getConfiguration(new GetConfigurationRequest().withApplication(application)
+                                                                                     .withEnvironment(environment)
+                                                                                     .withConfiguration(configurationName)
+                                                                                     .withClientId(clientId)
+                                                                                     .withClientConfigurationVersion(previousVersion));
+
+    final Optional<DynamicConfiguration> maybeDynamicConfiguration;
+
+    if (!StringUtils.equals(lastConfigResult.getConfigurationVersion(), previousVersion)) {
+      logger.info("Received new config version: {}", lastConfigResult.getConfigurationVersion());
+      maybeDynamicConfiguration = Optional.of(mapper.readValue(StandardCharsets.UTF_8.decode(lastConfigResult.getContent().asReadOnlyBuffer()).toString(), DynamicConfiguration.class));
+    } else {
+      // No change since last version
+      maybeDynamicConfiguration = Optional.empty();
+    }
+
+    return maybeDynamicConfiguration;
+  }
+
+  private DynamicConfiguration retrieveInitialDynamicConfiguration() {
+    for (;;) {
+      try {
+        final Optional<DynamicConfiguration> maybeDynamicConfiguration = retrieveDynamicConfiguration();
+
+        if (maybeDynamicConfiguration.isPresent()) {
+          return maybeDynamicConfiguration.get();
+        } else {
+          throw new IllegalStateException("No initial configuration available");
+        }
+      } catch (Throwable t) {
+        logger.warn("Error retrieving initial dynamic configuration", t);
+        Util.sleep(1000);
+      }
+    }
+  }
+}