GUACAMOLE-317: Merge Add support for failover-only connections.

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/connection/ConnectionModel.java

@@ -61,6 +61,13 @@ public class ConnectionModel extends ChildObjectModel {
      */
     private Integer connectionWeight;
 
+    /**
+     * Whether this connection should be reserved for failover. Failover-only
+     * connections within a balancing group are only used when all non-failover
+     * connections are unavailable.
+     */
+    private boolean failoverOnly;
+
     /**
      * The identifiers of all readable sharing profiles associated with this
      * connection.
@@ -196,6 +203,32 @@ public class ConnectionModel extends ChildObjectModel {
         return connectionWeight;
     }
 
+    /**
+     * Returns whether this connection should be reserved for failover.
+     * Failover-only connections within a balancing group are only used when
+     * all non-failover connections are unavailable.
+     *
+     * @return
+     *     true if this connection should be reserved for failover, false
+     *     otherwise.
+     */
+    public boolean isFailoverOnly() {
+        return failoverOnly;
+    }
+
+    /**
+     * Sets whether this connection should be reserved for failover.
+     * Failover-only connections within a balancing group are only used when
+     * all non-failover connections are unavailable.
+     *
+     * @param failoverOnly
+     *     true if this connection should be reserved for failover, false
+     *     otherwise.
+     */
+    public void setFailoverOnly(boolean failoverOnly) {
+        this.failoverOnly = failoverOnly;
+    }
+
     /**
      * Sets the maximum number of connections that can be established to this
      * connection concurrently by any one user.

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/connection/ModeledConnection.java

@@ -32,6 +32,7 @@ import org.apache.guacamole.auth.jdbc.tunnel.GuacamoleTunnelService;
 import org.apache.guacamole.GuacamoleException;
 import org.apache.guacamole.auth.jdbc.JDBCEnvironment;
 import org.apache.guacamole.auth.jdbc.base.ModeledChildDirectoryObject;
+import org.apache.guacamole.form.BooleanField;
 import org.apache.guacamole.form.EnumField;
 import org.apache.guacamole.form.Field;
 import org.apache.guacamole.form.Form;
@@ -121,6 +122,13 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
      */
     public static final String CONNECTION_WEIGHT = "weight";
 
+    /**
+     * The name of the attribute which controls whether the connection should
+     * be used as a spare only (all other non-spare connections within the same
+     * balancing group should be preferred).
+     */
+    public static final String FAILOVER_ONLY_NAME = "failover-only";
+
     /**
      * All attributes related to restricting user accounts, within a logical
      * form.
@@ -134,7 +142,8 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
      * All attributes related to load balancing in a logical form.
      */
     public static final Form LOAD_BALANCING = new Form("load-balancing", Arrays.<Field>asList(
-        new NumericField(CONNECTION_WEIGHT)
+        new NumericField(CONNECTION_WEIGHT),
+        new BooleanField(FAILOVER_ONLY_NAME, "true")
     ));
 
     /**
@@ -281,6 +290,9 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
         // Set connection weight
         attributes.put(CONNECTION_WEIGHT, NumericField.format(getModel().getConnectionWeight()));
 
+        // Set whether connection is failover-only
+        attributes.put(FAILOVER_ONLY_NAME, getModel().isFailoverOnly() ? "true" : null);
+
         return attributes;
     }
 
@@ -333,6 +345,9 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
             logger.debug("Unable to parse numeric attribute.", e);
         }
 
+        // Translate failover-only attribute
+        getModel().setFailoverOnly("true".equals(attributes.get(FAILOVER_ONLY_NAME)));
+
     }
 
     /**
@@ -436,4 +451,17 @@ public class ModeledConnection extends ModeledChildDirectoryObject<ConnectionMod
 
     }
 
+    /**
+     * Returns whether this connection should be reserved for failover.
+     * Failover-only connections within a balancing group are only used when
+     * all non-failover connections are unavailable.
+     *
+     * @return
+     *     true if this connection should be reserved for failover, false
+     *     otherwise.
+     */
+    public boolean isFailoverOnly() {
+        return getModel().isFailoverOnly();
+    }
+
 }

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/tunnel/AbstractGuacamoleTunnelService.java

@@ -44,7 +44,6 @@ import org.apache.guacamole.GuacamoleResourceNotFoundException;
 import org.apache.guacamole.GuacamoleSecurityException;
 import org.apache.guacamole.GuacamoleServerException;
 import org.apache.guacamole.GuacamoleUpstreamException;
-import org.apache.guacamole.auth.jdbc.JDBCEnvironment;
 import org.apache.guacamole.auth.jdbc.connection.ConnectionMapper;
 import org.apache.guacamole.net.GuacamoleSocket;
 import org.apache.guacamole.net.GuacamoleTunnel;
@@ -143,6 +142,10 @@ public abstract class AbstractGuacamoleTunnelService implements GuacamoleTunnelS
      * @param connections
      *     The connections being accessed.
      *
+     * @param includeFailoverOnly
+     *     Whether connections which have been designated for use in failover
+     *     situations only (hot spares) may be considered.
+     *
      * @return
      *     The connection that has been acquired on behalf of the given user.
      *
@@ -150,7 +153,8 @@ public abstract class AbstractGuacamoleTunnelService implements GuacamoleTunnelS
      *     If access is denied to the given user for any reason.
      */
     protected abstract ModeledConnection acquire(RemoteAuthenticatedUser user,
-            List<ModeledConnection> connections) throws GuacamoleException;
+            List<ModeledConnection> connections, boolean includeFailoverOnly)
+            throws GuacamoleException;
 
     /**
      * Releases possibly-exclusive access to the given connection on behalf of
@@ -647,8 +651,8 @@ public abstract class AbstractGuacamoleTunnelService implements GuacamoleTunnelS
             final ModeledConnection connection, GuacamoleClientInformation info)
             throws GuacamoleException {
 
-        // Acquire access to single connection
-        acquire(user, Collections.singletonList(connection));
+        // Acquire access to single connection, ignoring the failover-only flag
+        acquire(user, Collections.singletonList(connection), true);
 
         // Connect only if the connection was successfully acquired
         ActiveConnectionRecord connectionRecord = activeConnectionRecordProvider.get();
@@ -668,6 +672,9 @@ public abstract class AbstractGuacamoleTunnelService implements GuacamoleTunnelS
             ModeledConnectionGroup connectionGroup,
             GuacamoleClientInformation info) throws GuacamoleException {
 
+        // Track failures in upstream (remote desktop) connections
+        boolean upstreamHasFailed = false;
+
         // If group has no associated balanced connections, cannot connect
         List<ModeledConnection> connections = getBalancedConnections(user, connectionGroup);
         if (connections.isEmpty())
@@ -678,10 +685,11 @@ public abstract class AbstractGuacamoleTunnelService implements GuacamoleTunnelS
             // Acquire group
             acquire(user, connectionGroup);
 
-            // Attempt to acquire to any child
+            // Attempt to acquire to any child, including failover-only
+            // connections only if at least one upstream failure has occurred
             ModeledConnection connection;
             try {
-                connection = acquire(user, connections);
+                connection = acquire(user, connections, upstreamHasFailed);
             }
 
             // Ensure connection group is always released if child acquire fails
@@ -701,6 +709,14 @@ public abstract class AbstractGuacamoleTunnelService implements GuacamoleTunnelS
                 if (connectionGroup.isSessionAffinityEnabled())
                     user.preferConnection(connection.getIdentifier());
 
+                // Warn if we are connecting to a failover-only connection
+                if (connection.isFailoverOnly())
+                    logger.warn("One or more normal connections within "
+                            + "group \"{}\" have failed. Some connection "
+                            + "attempts are being routed to designated "
+                            + "failover-only connections.",
+                            connectionGroup.getIdentifier());
+
                 return tunnel;
 
             }
@@ -711,6 +727,7 @@ public abstract class AbstractGuacamoleTunnelService implements GuacamoleTunnelS
                 logger.info("Upstream error intercepted for connection \"{}\". Failing over to next connection in group...", connection.getIdentifier());
                 logger.debug("Upstream remote desktop reported an error during connection.", e);
                 connections.remove(connection);
+                upstreamHasFailed = true;
             }
 
         } while (!connections.isEmpty());

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/tunnel/RestrictedGuacamoleTunnelService.java

@@ -171,7 +171,8 @@ public class RestrictedGuacamoleTunnelService
 
     @Override
     protected ModeledConnection acquire(RemoteAuthenticatedUser user,
-            List<ModeledConnection> connections) throws GuacamoleException {
+            List<ModeledConnection> connections, boolean includeFailoverOnly)
+            throws GuacamoleException {
 
         // Do not acquire connection unless within overall limits
         if (!tryIncrement(totalActiveConnections, environment.getAbsoluteMaxConnections()))
@@ -222,6 +223,11 @@ public class RestrictedGuacamoleTunnelService
                 continue;
             }
 
+            // Skip connections which are failover-only if they are excluded
+            // from this connection attempt
+            if (!includeFailoverOnly && connection.isFailoverOnly())
+                continue;
+
             // Attempt to aquire connection according to per-user limits
             Seat seat = new Seat(username, connection.getIdentifier());
             if (tryAdd(activeSeats, seat,

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/resources/translations/en.json

@@ -20,6 +20,7 @@
         "FIELD_HEADER_MAX_CONNECTIONS"          : "Maximum number of connections:",
         "FIELD_HEADER_MAX_CONNECTIONS_PER_USER" : "Maximum number of connections per user:",
 
+        "FIELD_HEADER_FAILOVER_ONLY"            : "Use for failover only:",
         "FIELD_HEADER_WEIGHT"                   : "Connection weight:",
 
         "FIELD_HEADER_GUACD_HOSTNAME"   : "Hostname:",

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/schema/001-create-schema.sql

@@ -65,9 +65,9 @@ CREATE TABLE `guacamole_connection` (
   `max_connections`          int(11),
   `max_connections_per_user` int(11),
   
-  -- Connection weight
+  -- Load-balancing behavior
   `connection_weight`        int(11),
-
+  `failover_only`            boolean NOT NULL DEFAULT 0,
 
   PRIMARY KEY (`connection_id`),
   UNIQUE KEY `connection_name_parent` (`connection_name`, `parent_id`),

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/schema/upgrade/upgrade-pre-0.9.14.sql

@@ -23,3 +23,10 @@
 
 ALTER TABLE guacamole_connection
     ADD COLUMN connection_weight int(11);
+
+--
+-- Add failover-only flag
+--
+
+ALTER TABLE guacamole_connection
+    ADD COLUMN failover_only BOOLEAN NOT NULL DEFAULT 0;

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/resources/org/apache/guacamole/auth/jdbc/connection/ConnectionMapper.xml

@@ -38,6 +38,7 @@
         <result column="proxy_encryption_method"  property="proxyEncryptionMethod" jdbcType="VARCHAR"
                 javaType="org.apache.guacamole.net.auth.GuacamoleProxyConfiguration$EncryptionMethod"/>
         <result column="connection_weight"        property="connectionWeight"      jdbcType="INTEGER"/>
+        <result column="failover_only"            property="failoverOnly"          jdbcType="BOOLEAN"/>
 
         <!-- Associated sharing profiles -->
         <collection property="sharingProfileIdentifiers" resultSet="sharingProfiles" ofType="java.lang.String"
@@ -97,7 +98,8 @@
             proxy_hostname,
             proxy_port,
             proxy_encryption_method,
-            connection_weight
+            connection_weight,
+            failover_only
         FROM guacamole_connection
         WHERE connection_id IN
             <foreach collection="identifiers" item="identifier"
@@ -129,7 +131,8 @@
             proxy_hostname,
             proxy_port,
             proxy_encryption_method,
-            connection_weight
+            connection_weight,
+            failover_only
         FROM guacamole_connection
         JOIN guacamole_connection_permission ON guacamole_connection_permission.connection_id = guacamole_connection.connection_id
         WHERE guacamole_connection.connection_id IN
@@ -166,7 +169,8 @@
             proxy_hostname,
             proxy_port,
             proxy_encryption_method,
-            connection_weight
+            connection_weight,
+            failover_only
         FROM guacamole_connection
         WHERE 
             <if test="parentIdentifier != null">parent_id = #{parentIdentifier,jdbcType=VARCHAR}</if>
@@ -194,7 +198,8 @@
             proxy_hostname,
             proxy_port,
             proxy_encryption_method,
-            connection_weight
+            connection_weight,
+            failover_only
         )
         VALUES (
             #{object.name,jdbcType=VARCHAR},
@@ -205,7 +210,8 @@
             #{object.proxyHostname,jdbcType=VARCHAR},
             #{object.proxyPort,jdbcType=INTEGER},
             #{object.proxyEncryptionMethod,jdbcType=VARCHAR},
-            #{object.connectionWeight,jdbcType=INTEGER}
+            #{object.connectionWeight,jdbcType=INTEGER},
+            #{object.failoverOnly,jdbcType=BOOLEAN}
         )
 
     </insert>
@@ -221,7 +227,8 @@
             proxy_hostname           = #{object.proxyHostname,jdbcType=VARCHAR},
             proxy_port               = #{object.proxyPort,jdbcType=INTEGER},
             proxy_encryption_method  = #{object.proxyEncryptionMethod,jdbcType=VARCHAR},
-            connection_weight        = #{object.connectionWeight,jdbcType=INTEGER}
+            connection_weight        = #{object.connectionWeight,jdbcType=INTEGER},
+            failover_only            = #{object.failoverOnly,jdbcType=BOOLEAN}
         WHERE connection_id = #{object.objectID,jdbcType=INTEGER}
     </update>
 

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-postgresql/schema/001-create-schema.sql

@@ -108,6 +108,7 @@ CREATE TABLE guacamole_connection (
 
   -- Connection Weight
   connection_weight        integer,
+  failover_only            boolean NOT NULL DEFAULT FALSE,
 
   -- Guacamole proxy (guacd) overrides
   proxy_port              integer,

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-postgresql/schema/upgrade/upgrade-pre-0.9.14.sql

@@ -23,3 +23,10 @@
 
 ALTER TABLE guacamole_connection
     ADD COLUMN connection_weight int;
+
+--
+-- Add failover-only flag
+--
+
+ALTER TABLE guacamole_connection
+    ADD COLUMN failover_only BOOLEAN NOT NULL DEFAULT FALSE;

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-postgresql/src/main/resources/org/apache/guacamole/auth/jdbc/connection/ConnectionMapper.xml

@@ -38,6 +38,7 @@
         <result column="proxy_encryption_method"  property="proxyEncryptionMethod" jdbcType="VARCHAR"
                 javaType="org.apache.guacamole.net.auth.GuacamoleProxyConfiguration$EncryptionMethod"/>
         <result column="connection_weight"        property="connectionWeight"      jdbcType="INTEGER"/>
+        <result column="failover_only"            property="failoverOnly"          jdbcType="BOOLEAN"/>
 
         <!-- Associated sharing profiles -->
         <collection property="sharingProfileIdentifiers" resultSet="sharingProfiles" ofType="java.lang.String"
@@ -97,7 +98,8 @@
             proxy_hostname,
             proxy_port,
             proxy_encryption_method,
-            connection_weight
+            connection_weight,
+            failover_only
         FROM guacamole_connection
         WHERE connection_id IN
             <foreach collection="identifiers" item="identifier"
@@ -129,7 +131,8 @@
             proxy_hostname,
             proxy_port,
             proxy_encryption_method,
-            connection_weight
+            connection_weight,
+            failover_only
         FROM guacamole_connection
         JOIN guacamole_connection_permission ON guacamole_connection_permission.connection_id = guacamole_connection.connection_id
         WHERE guacamole_connection.connection_id IN
@@ -166,7 +169,8 @@
             proxy_hostname,
             proxy_port,
             proxy_encryption_method,
-            connection_weight
+            connection_weight,
+            failover_only
         FROM guacamole_connection
         WHERE 
             <if test="parentIdentifier != null">parent_id = #{parentIdentifier,jdbcType=INTEGER}::integer</if>
@@ -194,7 +198,8 @@
             proxy_hostname,
             proxy_port,
             proxy_encryption_method,
-            connection_weight
+            connection_weight,
+            failover_only
         )
         VALUES (
             #{object.name,jdbcType=VARCHAR},
@@ -205,7 +210,8 @@
             #{object.proxyHostname,jdbcType=VARCHAR},
             #{object.proxyPort,jdbcType=INTEGER},
             #{object.proxyEncryptionMethod,jdbcType=VARCHAR}::guacamole_proxy_encryption_method,
-            #{object.connectionWeight,jdbcType=INTEGER}
+            #{object.connectionWeight,jdbcType=INTEGER},
+            #{object.failoverOnly,jdbcType=BOOLEAN}
         )
 
     </insert>
@@ -221,7 +227,8 @@
             proxy_hostname           = #{object.proxyHostname,jdbcType=VARCHAR},
             proxy_port               = #{object.proxyPort,jdbcType=INTEGER},
             proxy_encryption_method  = #{object.proxyEncryptionMethod,jdbcType=VARCHAR}::guacamole_proxy_encryption_method,
-            connection_weight        = #{object.connectionWeight,jdbcType=INTEGER}
+            connection_weight        = #{object.connectionWeight,jdbcType=INTEGER},
+            failover_only            = #{object.failoverOnly,jdbcType=BOOLEAN}
         WHERE connection_id = #{object.objectID,jdbcType=INTEGER}::integer
     </update>