GUACAMOLE-374: Restore support for legacy Docker links.

guacamole-docker/entrypoint.d/000-migrate-docker-links.sh

@@ -0,0 +1,136 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+##
+## @fn 000-migrate-docker-links.sh
+##
+## Checks for usage of any Docker links that were formerly supported
+## but are now deprecated, warning when any deprecated Docker links are
+## encountered. Until support for Docker links is entirely removed, the values
+## of environment variables that are injected by Docker for deprecated Docker
+## links are automatically reassigned to currently supported variables.
+##
+
+##
+## Unsets all environment variables whose names start with the given prefix.
+##
+## @param LEGACY_VAR_PREFIX
+##     The name prefix of the environment variables that should be unset.
+##
+unset_starts_with() {
+
+    local LEGACY_VAR_PREFIX="$1"
+
+    local LEGACY_VAR_NAME
+
+    # Unset all environment variables starting with the given prefix
+    while read -r LEGACY_VAR_NAME; do
+        unset "$LEGACY_VAR_NAME"
+    done < <(awk 'BEGIN{for(v in ENVIRON) print v}' | grep "^$LEGACY_VAR_PREFIX")
+
+}
+
+##
+## Checks for usage of the given deprecated Docker link, automatically
+## assigning the values of its associated environment variables to the given
+## set of currently supported environment variables.  If usage of the
+## deprecated Docker link is found, a warning is printed to STDERR.
+##
+## @param LEGACY_LINK_NAME
+##     The name of the Docker link that's deprecated, as would be provided to
+##     the "docker" command with the "--link" option.
+##
+## @param LEGACY_LINK_PORT_NUMBER
+##     The TCP port number used by the service originally pointed to by the
+##     deprecated Docker link. This will be the port number exposed by the
+##     Docker image customarily used for that service.
+##
+## @param CURRENT_ADDR_VAR_NAME
+##     The name of the environment variable that is currently supported and
+##     represents the IP addresss or hostname of the service originally pointed
+##     to by the deprecated Docker link.
+##
+## @param CURRENT_PORT_VAR_NAME
+##     The name of the environment variable that is currently supported and
+##     represents the TCP port of the service originally pointed to by the
+##     deprecated Docker link.
+##
+deprecate_link() {
+
+    local LEGACY_LINK_NAME="$1"
+    local LEGACY_LINK_PORT_NUMBER="$2"
+    local CURRENT_ADDR_VAR_NAME="$3"
+    local CURRENT_PORT_VAR_NAME="$4"
+
+    # Determine names of environment variables injected by Docker for the link
+    # having the given name
+    local LEGACY_LINK_VAR_PREFIX="`echo "$LEGACY_LINK_NAME" | tr 'a-z' 'A-Z'`"
+    local LEGACY_LINK_VAR_TCP_PREFIX="${LEGACY_LINK_VAR_PREFIX}_PORT_${LEGACY_LINK_PORT_NUMBER}_TCP"
+    local LEGACY_ADDR_VAR_NAME="${LEGACY_LINK_VAR_TCP_PREFIX}_ADDR"
+    local LEGACY_PORT_VAR_NAME="${LEGACY_LINK_VAR_TCP_PREFIX}_PORT"
+
+    # NOTE: We pull these values early to ensure we can safely unset the
+    # legacy variables without losing the ability to reassign those values to
+    # the proper variables later
+    local LEGACY_LINK_ADDR="${!LEGACY_ADDR_VAR_NAME}"
+    local LEGACY_LINK_PORT="${!LEGACY_PORT_VAR_NAME}"
+
+    if [ -n "$LEGACY_LINK_ADDR" -o -n "$LEGACY_LINK_PORT" ]; then
+        echo "WARNING: The \"$LEGACY_LINK_NAME\" Docker link has been deprecated in favor of the \"$CURRENT_ADDR_VAR_NAME\" and \"$CURRENT_PORT_VAR_NAME\" environment variables. Please migrate your configuration when possible, as Docker considers the linking feature to be legacy and support for Docker links may be removed in future releases. See: https://docs.docker.com/engine/network/links/" >&2
+
+        #
+        # Clear out any environment variables related to the legacy link (NOTE:
+        # this is necessary not only to clean the environment of variables that
+        # aren't actually used, but also to avoid tripping warnings about
+        # legacy "POSTGRES_" variable naming).
+        #
+        # The variables that Docker will set are documented here:
+        #
+        #   https://docs.docker.com/engine/network/links/
+        #
+
+        unset "${LEGACY_LINK_VAR_PREFIX}_NAME"
+        unset "${LEGACY_LINK_VAR_PREFIX}_PORT"
+        unset_starts_with "${LEGACY_LINK_VAR_TCP_PREFIX}_"
+        unset_starts_with "${LEGACY_LINK_VAR_PREFIX}_ENV_"
+
+        # A variable containing just the prefix documented by Docker is also
+        # injected, but this is not documented at the above URL
+        unset "$LEGACY_LINK_VAR_TCP_PREFIX"
+
+        # Migrate legacy Docker link values over to the proper variables
+        export "$CURRENT_ADDR_VAR_NAME"="$LEGACY_LINK_ADDR"
+        export "$CURRENT_PORT_VAR_NAME"="$LEGACY_LINK_PORT"
+
+    fi
+
+}
+
+# Legacy Docker link support for connecting the webapp image with guacd
+deprecate_link "guacd" 4822 "GUACD_HOSTNAME" "GUACD_PORT"
+
+# Legacy Docker link support for connecting the webapp image with the various
+# supported databases
+deprecate_link "mysql"     3306 "MYSQL_HOSTNAME"      "MYSQL_PORT"
+deprecate_link "postgres"  5432 "POSTGRESQL_HOSTNAME" "POSTGRESQL_PORT"
+deprecate_link "sqlserver" 1433 "SQLSERVER_HOSTNAME"  "SQLSERVER_PORT"
+
+# No other Docker links have been historically supported by the
+# "guacamole/guacamole" image.
+

guacamole-docker/entrypoint.d/000-migrate-legacy-variables.sh → guacamole-docker/entrypoint.d/010-migrate-legacy-variables.sh

@@ -18,7 +18,7 @@
 #
 
 ##
-## @fn 000-migrate-legacy-variables.sh
+## @fn 010-migrate-legacy-variables.sh
 ##
 ## Checks for usage of any environment variables that were formerly supported
 ## but are now deprecated, warning when any deprecated variables are