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

Structure

Non-mandatory fields are described in italics.

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

FieldWhat is it used forSample 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
displayNamethe display name of the service
HDFS
versionthe 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
componentsthe list of component that the service is comprised of<check out HDFS metainfo>
osSpecificsOS specific package information for the service<check out HDFS metainfo>
commandScriptservice level commands may also be defined. The command is executed on a component instance that is a client<check out HDFS metainfo>
commenta short description describing the service
Apache Hadoop Distributed File System
requiredServiceswhat other services that should be present on the cluster<check out HDFS metainfo>
configuration-dependenciesconfiguration files that are expected by the service (config files owned by other services are specified in this list)<check out HDFS metainfo>
restartRequiredAfterRackChangeRestart Required After Rack Changetrue / false
configuration-dirUse this to specify a different config directory if not 'configuration'-

 


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

FieldWhat is it used forSample Values
namename of the component
HDFS
displayNamedisplay name of the component.
HDFS
categorytype of the component - MASTER, SLAVE, and CLIENT
2.1.0.2.0
commandScriptapplication wide commands may also be defined. The command is executed on a component instance that is a client<check out HDFS metainfo>
cardinalityallowed/expected number of instancesFor example, 1-2 for MASTER, 1+ for Slave
reassignAllowedwhether the component can be reassigned / moved to a different host.true / false
versionAdvertiseddoes the component advertise its version - used during rolling/express upgrade
Apache Hadoop Distributed File System
timelineAppidThis will be the component name under which the metrics from this component will be collected.<check out HDFS metainfo>
dependenciesthe list of components that this component depends on<check out HDFS metainfo>
customCommandsa 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)

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

 

service/commandScript - the script that implements service check

FieldWhat is it used forSample Values
script
the relative path to the script
<commandScript>
  <script>scripts/service_check.py</script>
  <scriptType>PYTHON</scriptType>
  <timeout>300</timeout>
</commandScript>
scriptType
the type of the script, currently only supported type is PYTHON
timeout
custom timeout for the command - this supersedes ambari default 

service/component/dependencies/dependency

FieldWhat is it used forSample Values
name
name of the component it depends on
<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>
scope

cluster / host. specifies whether the dependent component

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.

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

service/component/logs - provides log search integration.

logId
logid of the component
<log>
  <logId>hdfs_namenode</logId>
  <primary>true</primary>
</log>
primary
 primary log id or not.  

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

<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>
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