versioned_docs/version-2.7.5/ambari-design/stack-and-services/writing-metainfo.md - ambari-website - Git at Google

 # Writing metainfo.xml

 metainfo.xml is a declarative definition of an Ambari managed service describing its content. Itis the most critical file for any service definition. This section describes various key sub-sections within a metainfo.xml file.

 _Non-mandatory fields are described in italics._

 The top level fields to describe a service are as follows:

 Feild | What is it used for | Sample Values
 ------|---------------------|---------------
 name  | the name of the service. A name has to be unique among all the services that are included in the stack definition containing the service.  | HDFS
 displayName | the display name of the service | HDFS
 version | the version of the service. name and version together uniquely identify a service. Usually, the version is the version of the service binary itself.  | 2.1.0.2.0
 components | the list of component that the service is comprised of  | `<check out HDFS metainfo>`
 osSpecifics | OS specific package information for the service | `<check out HDFS metainfo>`
 commandScript | service level commands may also be defined. The command is executed on a component instance that is a client | `<check out HDFS metainfo>`
 comment       | a short description describing the service  | Apache Hadoop Distributed File System
 requiredServices | what other services that should be present on the cluster | `<check out HDFS metainfo>`
 configuration-dependencies | configuration files that are expected by the service (config files owned by other services are specified in this list) | `<check out HDFS metainfo>`
 restartRequiredAfterRackChange | Restart Required After Rack Change  | true / false
 configuration-dir | Use this to specify a different config directory if not 'configuration' | -

 **service/components - A service contains several components. The fields associated with a component are**:

 Feild | What is it used for | Sample Values
 ------|---------------------|---------------
 name | name of the component | HDFS
 displayName | display name of the component.  | HDFS
 category | type of the component - MASTER, SLAVE, and CLIENT | 2.1.0.2.0
 commandScript | application wide commands may also be defined. The command is executed on a component instance that is a client | `<check out HDFS metainfo>`
 cardinality | allowed/expected number of instances  | For example, 1-2 for MASTER, 1+ for Slave
 reassignAllowed | whether the component can be reassigned / moved to a different host.  | true / false
 versionAdvertised | does the component advertise its version - used during rolling/express upgrade  | Apache Hadoop Distributed File System
 timelineAppid | This will be the component name under which the metrics from this component will be collected. | `<check out HDFS metainfo>`
 dependencies | the list of components that this component depends on | `<check out HDFS metainfo>`
 customCommands | a set of custom commands associated with the component in addition to standard commands. | RESTART_LLAP (Check out HIVE metainfo)

 **service/osSpecifics - OS specific package names (rpm or deb packages)**

 Feild | What is it used for | Sample Values
 ------|---------------------|---------------
 osFamily | the os family for which the package is applicable | any => all<br></br>amazon2015,redhat6,debian7,ubuntu12,ubuntu14,ubuntu16
 packages  | list of packages that are needed to deploy the service | `<check out HDFS metainfo>`
 package/name | name of the package (will be used by the yum/zypper/apt commands) | Eg hadoop-lzo.

 **service/commandScript - the script that implements service check**

 Feild | What is it used for
 ------|---------------------
 script | the relative path to the script
 scriptType | the type of the script, currently only supported type is PYTHON
 timeout | custom timeout for the command - this supersedes ambari default

 sample values:

 ```xml
 <commandScript>
   <script>scripts/service_check.py</script>
   <scriptType>PYTHON</scriptType>
   <timeout>300</timeout>
 </commandScript>
 ```
 **service/component/dependencies/dependency**

 Feild | What is it used for
 ------|---------------------
 name | name of the component it depends on
 scope | cluster / host. specifies whether the dependent component<br></br>should be present in the same cluster or the same host.
 auto-deploy | custom timeout for the command - this supersedes ambari default
 conditions | Conditions in which this dependency exists. For example, the presence of a property in a config.

 sample values:

 ```xml
 <dependency>
   <name>HDFS/ZKFC</name>
   <scope>cluster</scope>
   <auto-deploy>
     <enabled>false</enabled>
   </auto-deploy>
   <conditions>
     <condition xsi:type="propertyExists">
       <configType>hdfs-site</configType>
       <property>dfs.nameservices</property>
     </condition>
   </conditions>
 </dependency>
 ```

 **service/component/commandScript - the script that implements components specific default commands (Similar to service/commandScript )**

 **service/component/logs - provides log search integration.**

 Feild | What is it used for
 ------|---------------------
 logId | logid of the component
 primary | primary log id or not.

 sample values:

 ```xml
 <log>
   <logId>hdfs_namenode</logId>
   <primary>true</primary>
 </log>
 ```

 **service/component/customCommand - custom commands can be added to components.**

 - **name**: name of the custom command
 - **commandScript**: the details of the script that implements the custom command
 - commandScript/script: the relative path to the script
 - commandScript/scriptType: the type of the script, currently only supported type is PYTHON
 - commandScript/timeout: custom timeout for the command - this supersedes ambari default

 **service/component/configFiles - list of config files to be available when client config is to be downloaded (used to configure service clients that are not managed by Ambari)**

 - **type**: the type of file to be generated, xml or env sh, yaml, etc
 - **fileName**: name of the generated file
 - **dictionary**: data dictionary that contains the config properties (relevant to how ambari manages config bags internally)

 ## Sample metainfo.xml

 ```xml
 <metainfo>
   <schemaVersion>2.0</schemaVersion>
   <services>
     <service>
       <name>HBASE</name>
       <displayName>HBase</displayName>
       <comment>Non-relational distributed database and centralized service for configuration management &amp;
  synchronization
       </comment>
       <version>0.96.0.2.0</version>
       <components>
         <component>
           <name>HBASE_MASTER</name>
           <displayName>HBase Master</displayName>
           <category>MASTER</category>
           <cardinality>1+</cardinality>
           <versionAdvertised>true</versionAdvertised>
           <timelineAppid>HBASE</timelineAppid>
           <dependencies>
             <dependency>
               <name>HDFS/HDFS_CLIENT</name>
               <scope>host</scope>
               <auto-deploy>
                 <enabled>true</enabled>
               </auto-deploy>
             </dependency>
             <dependency>
               <name>ZOOKEEPER/ZOOKEEPER_SERVER</name>
               <scope>cluster</scope>
               <auto-deploy>
                 <enabled>true</enabled>
                 <co-locate>HBASE/HBASE_MASTER</co-locate>
               </auto-deploy>
             </dependency>
           </dependencies>
           <commandScript>
             <script>scripts/hbase_master.py</script>
             <scriptType>PYTHON</scriptType>
             <timeout>1200</timeout>
           </commandScript>
           <customCommands>
             <customCommand>
               <name>DECOMMISSION</name>
               <commandScript>
                 <script>scripts/hbase_master.py</script>
                 <scriptType>PYTHON</scriptType>
                 <timeout>600</timeout>
               </commandScript>
             </customCommand>
           </customCommands>
         </component>

         <component>
           <name>HBASE_REGIONSERVER</name>
           <displayName>RegionServer</displayName>
           <category>SLAVE</category>
           <cardinality>1+</cardinality>
           <versionAdvertised>true</versionAdvertised>
           <timelineAppid>HBASE</timelineAppid>
           <commandScript>
             <script>scripts/hbase_regionserver.py</script>
             <scriptType>PYTHON</scriptType>
           </commandScript>
         </component>

         <component>
           <name>HBASE_CLIENT</name>
           <displayName>HBase Client</displayName>
           <category>CLIENT</category>
           <cardinality>1+</cardinality>
           <versionAdvertised>true</versionAdvertised>
           <commandScript>
             <script>scripts/hbase_client.py</script>
             <scriptType>PYTHON</scriptType>
           </commandScript>
           <configFiles>
             <configFile>
               <type>xml</type>
               <fileName>hbase-site.xml</fileName>
               <dictionaryName>hbase-site</dictionaryName>
             </configFile>
             <configFile>
               <type>env</type>
               <fileName>hbase-env.sh</fileName>
               <dictionaryName>hbase-env</dictionaryName>
             </configFile>
           </configFiles>
         </component>
       </components>

       <osSpecifics>
         <osSpecific>
           <osFamily>any</osFamily>
           <packages>
             <package>
               <name>hbase</name>
             </package>
           </packages>
         </osSpecific>
       </osSpecifics>

       <commandScript>
         <script>scripts/service_check.py</script>
         <scriptType>PYTHON</scriptType>
         <timeout>300</timeout>
       </commandScript>

       <requiredServices>
         <service>ZOOKEEPER</service>
         <service>HDFS</service>
       </requiredServices>

       <configuration-dependencies>
         <config-type>core-site</config-type>
         <config-type>hbase-site</config-type>
         <config-type>ranger-hbase-policymgr-ssl</config-type>
         <config-type>ranger-hbase-security</config-type>
       </configuration-dependencies>

     </service>
   </services>
 </metainfo>
 ```
	# Writing metainfo.xml

	metainfo.xml is a declarative definition of an Ambari managed service describing its content. Itis the most critical file for any service definition. This section describes various key sub-sections within a metainfo.xml file.

	_Non-mandatory fields are described in italics._

	The top level fields to describe a service are as follows:

	Feild \| What is it used for \| Sample Values
	------\|---------------------\|---------------
	name \| the name of the service. A name has to be unique among all the services that are included in the stack definition containing the service. \| HDFS
	displayName \| the display name of the service \| HDFS
	version \| the version of the service. name and version together uniquely identify a service. Usually, the version is the version of the service binary itself. \| 2.1.0.2.0
	components \| the list of component that the service is comprised of \| `<check out HDFS metainfo>`
	osSpecifics \| OS specific package information for the service \| `<check out HDFS metainfo>`
	commandScript \| service level commands may also be defined. The command is executed on a component instance that is a client \| `<check out HDFS metainfo>`
	comment \| a short description describing the service \| Apache Hadoop Distributed File System
	requiredServices \| what other services that should be present on the cluster \| `<check out HDFS metainfo>`
	configuration-dependencies \| configuration files that are expected by the service (config files owned by other services are specified in this list) \| `<check out HDFS metainfo>`
	restartRequiredAfterRackChange \| Restart Required After Rack Change \| true / false
	configuration-dir \| Use this to specify a different config directory if not 'configuration' \| -

	service/components - A service contains several components. The fields associated with a component are:

	Feild \| What is it used for \| Sample Values
	------\|---------------------\|---------------
	name \| name of the component \| HDFS
	displayName \| display name of the component. \| HDFS
	category \| type of the component - MASTER, SLAVE, and CLIENT \| 2.1.0.2.0
	commandScript \| application wide commands may also be defined. The command is executed on a component instance that is a client \| `<check out HDFS metainfo>`
	cardinality \| allowed/expected number of instances \| For example, 1-2 for MASTER, 1+ for Slave
	reassignAllowed \| whether the component can be reassigned / moved to a different host. \| true / false
	versionAdvertised \| does the component advertise its version - used during rolling/express upgrade \| Apache Hadoop Distributed File System
	timelineAppid \| This will be the component name under which the metrics from this component will be collected. \| `<check out HDFS metainfo>`
	dependencies \| the list of components that this component depends on \| `<check out HDFS metainfo>`
	customCommands \| a set of custom commands associated with the component in addition to standard commands. \| RESTART_LLAP (Check out HIVE metainfo)

	service/osSpecifics - OS specific package names (rpm or deb packages)

	Feild \| What is it used for \| Sample Values
	------\|---------------------\|---------------
	osFamily \| the os family for which the package is applicable \| any => all<br></br>amazon2015,redhat6,debian7,ubuntu12,ubuntu14,ubuntu16
	packages \| list of packages that are needed to deploy the service \| `<check out HDFS metainfo>`
	package/name \| name of the package (will be used by the yum/zypper/apt commands) \| Eg hadoop-lzo.

	service/commandScript - the script that implements service check

	Feild \| What is it used for
	------\|---------------------
	script \| the relative path to the script
	scriptType \| the type of the script, currently only supported type is PYTHON
	timeout \| custom timeout for the command - this supersedes ambari default

	sample values:

	```xml
	<commandScript>
	<script>scripts/service_check.py</script>
	<scriptType>PYTHON</scriptType>
	<timeout>300</timeout>
	</commandScript>
	```
	service/component/dependencies/dependency

	Feild \| What is it used for
	------\|---------------------
	name \| name of the component it depends on
	scope \| cluster / host. specifies whether the dependent component<br></br>should be present in the same cluster or the same host.
	auto-deploy \| custom timeout for the command - this supersedes ambari default
	conditions \| Conditions in which this dependency exists. For example, the presence of a property in a config.

	sample values:

	```xml
	<dependency>
	<name>HDFS/ZKFC</name>
	<scope>cluster</scope>
	<auto-deploy>
	<enabled>false</enabled>
	</auto-deploy>
	<conditions>
	<condition xsi:type="propertyExists">
	<configType>hdfs-site</configType>
	<property>dfs.nameservices</property>
	</condition>
	</conditions>
	</dependency>
	```

	service/component/commandScript - the script that implements components specific default commands (Similar to service/commandScript )

	service/component/logs - provides log search integration.

	Feild \| What is it used for
	------\|---------------------
	logId \| logid of the component
	primary \| primary log id or not.

	sample values:

	```xml
	<log>
	<logId>hdfs_namenode</logId>
	<primary>true</primary>
	</log>
	```

	service/component/customCommand - custom commands can be added to components.

	- name: name of the custom command
	- commandScript: the details of the script that implements the custom command
	- commandScript/script: the relative path to the script
	- commandScript/scriptType: the type of the script, currently only supported type is PYTHON
	- commandScript/timeout: custom timeout for the command - this supersedes ambari default

	service/component/configFiles - list of config files to be available when client config is to be downloaded (used to configure service clients that are not managed by Ambari)

	- type: the type of file to be generated, xml or env sh, yaml, etc
	- fileName: name of the generated file
	- dictionary: data dictionary that contains the config properties (relevant to how ambari manages config bags internally)

	## Sample metainfo.xml

	```xml
	<metainfo>
	<schemaVersion>2.0</schemaVersion>
	<services>
	<service>
	<name>HBASE</name>
	<displayName>HBase</displayName>
	<comment>Non-relational distributed database and centralized service for configuration management &
	synchronization
	</comment>
	<version>0.96.0.2.0</version>
	<components>
	<component>
	<name>HBASE_MASTER</name>
	<displayName>HBase Master</displayName>
	<category>MASTER</category>
	<cardinality>1+</cardinality>
	<versionAdvertised>true</versionAdvertised>
	<timelineAppid>HBASE</timelineAppid>
	<dependencies>
	<dependency>
	<name>HDFS/HDFS_CLIENT</name>
	<scope>host</scope>
	<auto-deploy>
	<enabled>true</enabled>
	</auto-deploy>
	</dependency>
	<dependency>
	<name>ZOOKEEPER/ZOOKEEPER_SERVER</name>
	<scope>cluster</scope>
	<auto-deploy>
	<enabled>true</enabled>
	<co-locate>HBASE/HBASE_MASTER</co-locate>
	</auto-deploy>
	</dependency>
	</dependencies>
	<commandScript>
	<script>scripts/hbase_master.py</script>
	<scriptType>PYTHON</scriptType>
	<timeout>1200</timeout>
	</commandScript>
	<customCommands>
	<customCommand>
	<name>DECOMMISSION</name>
	<commandScript>
	<script>scripts/hbase_master.py</script>
	<scriptType>PYTHON</scriptType>
	<timeout>600</timeout>
	</commandScript>
	</customCommand>
	</customCommands>
	</component>

	<component>
	<name>HBASE_REGIONSERVER</name>
	<displayName>RegionServer</displayName>
	<category>SLAVE</category>
	<cardinality>1+</cardinality>
	<versionAdvertised>true</versionAdvertised>
	<timelineAppid>HBASE</timelineAppid>
	<commandScript>
	<script>scripts/hbase_regionserver.py</script>
	<scriptType>PYTHON</scriptType>
	</commandScript>
	</component>

	<component>
	<name>HBASE_CLIENT</name>
	<displayName>HBase Client</displayName>
	<category>CLIENT</category>
	<cardinality>1+</cardinality>
	<versionAdvertised>true</versionAdvertised>
	<commandScript>
	<script>scripts/hbase_client.py</script>
	<scriptType>PYTHON</scriptType>
	</commandScript>
	<configFiles>
	<configFile>
	<type>xml</type>
	<fileName>hbase-site.xml</fileName>
	<dictionaryName>hbase-site</dictionaryName>
	</configFile>
	<configFile>
	<type>env</type>
	<fileName>hbase-env.sh</fileName>
	<dictionaryName>hbase-env</dictionaryName>
	</configFile>
	</configFiles>
	</component>
	</components>

	<osSpecifics>
	<osSpecific>
	<osFamily>any</osFamily>
	<packages>
	<package>
	<name>hbase</name>
	</package>
	</packages>
	</osSpecific>
	</osSpecifics>

	<commandScript>
	<script>scripts/service_check.py</script>
	<scriptType>PYTHON</scriptType>
	<timeout>300</timeout>
	</commandScript>

	<requiredServices>
	<service>ZOOKEEPER</service>
	<service>HDFS</service>
	</requiredServices>

	<configuration-dependencies>
	<config-type>core-site</config-type>
	<config-type>hbase-site</config-type>
	<config-type>ranger-hbase-policymgr-ssl</config-type>
	<config-type>ranger-hbase-security</config-type>
	</configuration-dependencies>

	</service>
	</services>
	</metainfo>
	```