GUACAMOLE-374: Restore support for legacy Docker links.

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

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+#
+# 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 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
+## encountered.  Until support for a deprecated variable is entirely removed,
+## the value provided for the deprecated variable is automatically assigned to
+## the currently-supported variable.
+##
+
+##
+## Checks for usage of the given deprecated environment variable, automatically
+## assigning its value to the given currently-supported environment variable.
+## If usage of the deprecated variable is found, a warning is printed to
+## STDERR.
+##
+## @param LEGACY_VAR_NAME
+##     The name of the environment variable that's deprecated.
+##
+## @param CURRENT_VAR_NAME
+##     The name of the environment variable that is currently supported and
+##     replaces the deprecated variable.
+##
+deprecate_variable() {
+
+    local LEGACY_VAR_NAME="$1"
+    local CURRENT_VAR_NAME="$2"
+
+    if [ -n "${!LEGACY_VAR_NAME}" ]; then
+        echo "WARNING: The \"$LEGACY_VAR_NAME\" environment variable has been deprecated in favor of \"$CURRENT_VAR_NAME\". Please migrate your configuration when possible, as support for the older name may be removed in future releases." >&2
+        export "$CURRENT_VAR_NAME"="${!LEGACY_VAR_NAME}"
+    fi
+
+}
+
+##
+## Checks for usage of any environment variables using the given deprecated
+## prefix, automatically assigning their values to corresponding environment
+## variables having the given currently-supported prefix. If usage of the
+## deprecated prefix is found, a warning is printed to STDERR.
+##
+## @param LEGACY_VAR_PREFIX
+##     The environment variable prefix that's deprecated.
+##
+## @param CURRENT_VAR_PREFIX
+##     The environment variable prefix that is currently supported and
+##     replaces the deprecated variable prefix.
+##
+deprecate_variable_prefix() {
+
+    local LEGACY_VAR_PREFIX="$1"
+    local CURRENT_VAR_PREFIX="$2"
+
+    local LEGACY_VAR_NAME
+    local CURRENT_VAR_NAME
+    local HAS_LEGACY_VARIABLES=0
+
+    # Automatically reassign all "POSTGRES_*" variables to "POSTGRESQL_*"
+    while read -r LEGACY_VAR_NAME; do
+        HAS_LEGACY_VARIABLES=1
+        CURRENT_VAR_NAME="$CURRENT_VAR_PREFIX${LEGACY_VAR_NAME#$LEGACY_VAR_PREFIX}"
+        export "$CURRENT_VAR_NAME"="${!LEGACY_VAR_NAME}"
+        unset "$LEGACY_VAR_NAME"
+    done < <(awk 'BEGIN{for(v in ENVIRON) print v}' | grep "^$LEGACY_VAR_PREFIX")
+
+    if [ "$HAS_LEGACY_VARIABLES" = "1" ]; then
+        echo "WARNING: The \"$LEGACY_VAR_PREFIX\" prefix for environment variables has been deprecated in favor of the \"$CURRENT_VAR_PREFIX\" prefix. Please migrate your configuration when possible, as support for the older prefix may be removed in future releases." >&2
+        export "$CURRENT_VAR_NAME"="$LEGACY_VAR_NAME"
+    fi
+
+}
+
+# The old "*_USER" style for configuring the user account to be used to access
+# the database is being replaced with "*_USERNAME" such that all environment
+# variables exactly correspond to the names of configuration properties from
+# guacamole.properties.
+deprecate_variable "MYSQL_USER"     "MYSQL_USERNAME"
+deprecate_variable "POSTGRES_USER"  "POSTGRESQL_USERNAME"
+deprecate_variable "SQLSERVER_USER" "SQLSERVER_USERNAME"
+
+# The old "POSTGRES_" prefix for configuring usage of PostgreSQL is being
+# replaced with "POSTGRESQL_" such that all environment variables exactly
+# correspond to the names of configuration properties from
+# guacamole.properties.
+deprecate_variable_prefix "POSTGRES_" "POSTGRESQL_"
+
+# The old "PROXY_*" names for attributes supported by RemoteIpValve are being
+# replaced with "REMOTE_IP_VALVE_*" attributes that more closely and
+# predictably match their attribute names
+deprecate_variable "PROXY_ALLOWED_IPS_REGEX" "REMOTE_IP_VALVE_INTERNAL_PROXIES"
+deprecate_variable "PROXY_IP_HEADER"         "REMOTE_IP_VALVE_REMOTE_IP_HEADER"
+deprecate_variable "PROXY_PROTOCOL_HEADER"   "REMOTE_IP_VALVE_PROTOCOL_HEADER"
+# NOTE: PROXY_BY_HEADER never worked as there is no "remoteIpProxiesHeader" attribute for RemoteIpValve
+
+# The old "LOGBACK_LEVEL" environment variable has been replaced with
+# "LOG_LEVEL" for consistency with the guacd image
+deprecate_variable "LOGBACK_LEVEL" "LOG_LEVEL"