AMBARI-24263. Restart services just before stack upgrade fails due to AMS package incompatibility errors, causing EU not to be started. (mpapirkovskyy) (#1707)

* AMBARI-24263. Restart services just before stack upgrade fails due to AMS package incompatibility errors, causing EU not to be started. (mpapirkovskyy)

* AMBARI-24263. Scriptlets logic update. Nullable metrics template. (mpapirkovskyy)

* AMBARI-24263. Conditional metrics templates. (mpapirkovskyy)

* AMBARI-24263. Templates typo fix. (mpapirkovskyy)

* AMBARI-24263. Fix template in config. (mpapirkovskyy)

* AMBARI-24263. Fix IFS usage side effects. (mpapirkovskyy)

* AMBARI-24263. Restart services just before stack upgrade fails due to AMS package incompatibility errors, causing EU not to be started. (mpapirkovskyy)
diff --git a/ambari-metrics-assembly/pom.xml b/ambari-metrics-assembly/pom.xml
index 5e6b2d6..f89b9df 100644
--- a/ambari-metrics-assembly/pom.xml
+++ b/ambari-metrics-assembly/pom.xml
@@ -389,7 +389,10 @@
                   <defaultFilemode>644</defaultFilemode>
                   <defaultUsername>root</defaultUsername>
                   <defaultGroupname>root</defaultGroupname>
-
+                  <preinstallScriptlet>
+                    <scriptFile>${project.build.directory}/resources/rpm/sink/preinstall.sh</scriptFile>
+                    <fileEncoding>utf-8</fileEncoding>
+                  </preinstallScriptlet>
                   <postinstallScriptlet>
                     <scriptFile>${project.build.directory}/resources/rpm/sink/postinstall.sh</scriptFile>
                     <fileEncoding>utf-8</fileEncoding>
diff --git a/ambari-metrics-assembly/src/main/package/deb/control/preinst b/ambari-metrics-assembly/src/main/package/deb/control/preinst
new file mode 100644
index 0000000..7560fb9
--- /dev/null
+++ b/ambari-metrics-assembly/src/main/package/deb/control/preinst
@@ -0,0 +1,45 @@
+#!/bin/bash
+# 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
+
+JAR_FILES_LEGACY_FOLDER="/usr/lib/ambari-metrics-sink-legacy"
+
+HADOOP_SINK_LINK="/usr/lib/ambari-metrics-hadoop-sink/ambari-metrics-hadoop-sink.jar"
+
+HADOOP_LEGACY_LINK_NAME="/usr/lib/ambari-metrics-hadoop-sink/ambari-metrics-hadoop-sink-legacy.jar"
+
+if [ -f ${HADOOP_SINK_LINK} ]
+then
+    old_jar=$(readlink -f ${HADOOP_SINK_LINK})
+    version_part=$(basename ${old_jar} | awk -F"-" '{print $7}')
+    IFS=. version=(${version_part})
+    unset IFS
+
+    if [[ ${version[0]} -le 2 && ${version[1]} -lt 7 ]] # backup only required on upgrade from version < 2.7
+    then
+        if [ ! -d "$JAR_FILES_LEGACY_FOLDER" ]
+        then
+            mkdir -p "$JAR_FILES_LEGACY_FOLDER"
+        fi
+        echo "Backing up Ambari metrics hadoop sink jar ${old_jar} -> $JAR_FILES_LEGACY_FOLDER/"
+        cp "${old_jar}" "${JAR_FILES_LEGACY_FOLDER}/"
+
+        HADOOP_SINK_LEGACY_JAR="$JAR_FILES_LEGACY_FOLDER/$(basename ${old_jar})"
+        echo "Creating symlink for backup jar $HADOOP_LEGACY_LINK_NAME -> $HADOOP_SINK_LEGACY_JAR"
+        rm -f "${HADOOP_LEGACY_LINK_NAME}" ; ln -s "${HADOOP_SINK_LEGACY_JAR}" "${HADOOP_LEGACY_LINK_NAME}"
+    fi
+fi
+
+exit 0
diff --git a/ambari-metrics-assembly/src/main/package/rpm/sink/preinstall.sh b/ambari-metrics-assembly/src/main/package/rpm/sink/preinstall.sh
new file mode 100644
index 0000000..7560fb9
--- /dev/null
+++ b/ambari-metrics-assembly/src/main/package/rpm/sink/preinstall.sh
@@ -0,0 +1,45 @@
+#!/bin/bash
+# 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
+
+JAR_FILES_LEGACY_FOLDER="/usr/lib/ambari-metrics-sink-legacy"
+
+HADOOP_SINK_LINK="/usr/lib/ambari-metrics-hadoop-sink/ambari-metrics-hadoop-sink.jar"
+
+HADOOP_LEGACY_LINK_NAME="/usr/lib/ambari-metrics-hadoop-sink/ambari-metrics-hadoop-sink-legacy.jar"
+
+if [ -f ${HADOOP_SINK_LINK} ]
+then
+    old_jar=$(readlink -f ${HADOOP_SINK_LINK})
+    version_part=$(basename ${old_jar} | awk -F"-" '{print $7}')
+    IFS=. version=(${version_part})
+    unset IFS
+
+    if [[ ${version[0]} -le 2 && ${version[1]} -lt 7 ]] # backup only required on upgrade from version < 2.7
+    then
+        if [ ! -d "$JAR_FILES_LEGACY_FOLDER" ]
+        then
+            mkdir -p "$JAR_FILES_LEGACY_FOLDER"
+        fi
+        echo "Backing up Ambari metrics hadoop sink jar ${old_jar} -> $JAR_FILES_LEGACY_FOLDER/"
+        cp "${old_jar}" "${JAR_FILES_LEGACY_FOLDER}/"
+
+        HADOOP_SINK_LEGACY_JAR="$JAR_FILES_LEGACY_FOLDER/$(basename ${old_jar})"
+        echo "Creating symlink for backup jar $HADOOP_LEGACY_LINK_NAME -> $HADOOP_SINK_LEGACY_JAR"
+        rm -f "${HADOOP_LEGACY_LINK_NAME}" ; ln -s "${HADOOP_SINK_LEGACY_JAR}" "${HADOOP_LEGACY_LINK_NAME}"
+    fi
+fi
+
+exit 0