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In this example, we will create a custom service called "SAMPLESRV". This service includes MASTER, SLAVE and CLIENT components.

Create

...

a Custom Service

  1. Create a directory named SAMPLESRV that will contain the service definition for SAMPLESRV.

    Code Block
    mkdir SAMPLESRV
cd SAMPLESRV

  2. Within the SAMPLESRV directory, create a metainfo.xml file that describes the new service.  For example:

    Code Block
    <?xml version="1.0"?>
<metainfo>
    <schemaVersion>2.0</schemaVersion>
    <services>
        <service>
            <name>SAMPLESRV</name>
            <displayName>New Sample Service</displayName>
            <comment>A New Sample Service</comment>
            <version>1.0.0</version>
            <components>
                <component>
                    <name>SAMPLESRV_MASTER</name>
                    <displayName>Sample Srv Master</displayName>
                    <category>MASTER</category>
                    <cardinality>1</cardinality>
                    <commandScript>
                        <script>scripts/master.py</script>
                        <scriptType>PYTHON</scriptType>
                        <timeout>600</timeout>
                    </commandScript>
                </component>
                <component>
                    <name>SAMPLESRV_SLAVE</name>
                    <displayName>Sample Srv Slave</displayName>
                    <category>SLAVE</category>
                    <cardinality>1+</cardinality>
                    <commandScript>
                        <script>scripts/slave.py</script>
                        <scriptType>PYTHON</scriptType>
                        <timeout>600</timeout>
                    </commandScript>
                </component>
                <component>
                    <name>SAMPLESRV_CLIENT</name>
                    <displayName>Sample Srv Client</displayName>
                    <category>CLIENT</category>
                    <cardinality>1+</cardinality>
                    <commandScript>
                        <script>scripts/sample_client.py</script>
                        <scriptType>PYTHON</scriptType>
                        <timeout>600</timeout>
                    </commandScript>
                </component>
            </components>
            <osSpecifics>
                <osSpecific>
                    <osFamily>any</osFamily>
                </osSpecific>
            </osSpecifics>
        </service>
    </services>
</metainfo>
  3. In the above, the service name is "SAMPLESRV", and it contains:
    • one MASTER component "SAMPLESRV_MASTER"
    • one SLAVE component "SAMPLESRV_SLAVE"
    • one CLIENT component "SAMPLESRV_CLIENT"

  4. Next, let's create that command script. Create a directory for the command script SAMPLESRV/package/scripts that we designated in the service metainfo.

    Code Block
    mkdir -p package/scripts
cd package/scripts

  5. Within the scripts directory, create the .py command script files mentioned in the metainfo.

    For example master.py file:

    Code Block
    import sys
from resource_management import *
class Master(Script):
  def install(self, env):
    print 'Install the Sample Srv Master';
  def configure(self, env):
    print 'Configure the Sample Srv Master';
  def stop(self, env):
    print 'Stop the Sample Srv Master';
  def start(self, env):
    print 'Start the Sample Srv Master';
  def status(self, env):
    print 'Status of the Sample Srv Master';
if __name__ == "__main__":
  Master().execute()

    For example slave.py file:

    Code Block
    import sys
from resource_management import *
class Slave(Script):
  def install(self, env):
    print 'Install the Sample Srv Slave';
  def configure(self, env):
    print 'Configure the Sample Srv Slave';
  def stop(self, env):
    print 'Stop the Sample Srv Slave';
  def start(self, env):
    print 'Start the Sample Srv Slave';
  def status(self, env):
    print 'Status of the Sample Srv Slave';
if __name__ == "__main__":
  Slave().execute()

    For example sample_client.py file:

    Code Block
    import sys
from resource_management import *
class SampleClient(Script):
  def install(self, env):
    print 'Install the Sample Srv Client';
  def configure(self, env):
    print 'Configure the Sample Srv Client';
if __name__ == "__main__":
  SampleClient().execute()

Implementing a

...

Custom Command

  1. Browse to the SAMPLESRV directory, and edit the metainfo.xml file that describes the service. For example, adding a custom command to the SAMPLESRV_CLIENT:

    Code Block
                    <component>
                    <name>SAMPLESRV_CLIENT</name>
                    <displayName>Sample Srv Client</displayName>
                    <category>CLIENT</category>
                    <cardinality>1+</cardinality>
                    <commandScript>
                        <script>scripts/sample_client.py</script>
                        <scriptType>PYTHON</scriptType>
                        <timeout>600</timeout>
                    </commandScript>
                    <customCommands>
                      <customCommand>
                        <name>SOMETHINGCUSTOM</name>
                        <commandScript>
                          <script>scripts/sample_client.py</script>
                          <scriptType>PYTHON</scriptType>
                          <timeout>600</timeout>
                        </commandScript>
                      </customCommand>
                    </customCommands>
                </component>
            </components>

  2. Next, let's create that command script by editing the package/scripts/sample_client.py file that we designated in the service metainfo.

    Code Block
    import sys
from resource_management import *

class SampleClient(Script):
  def install(self, env):
    print 'Install the Sample Srv Client';
  def configure(self, env):
    print 'Configure the Sample Srv Client';
  def somethingcustom(self, env):
    print 'Something custom';

if __name__ == "__main__":
  SampleClient().execute()

...

Adding Configs to the Custom Service

...

In this example, we will add a configuration type "test-config" to our SAMPLESRV.

  1. Modify the metainfo.xml

...

  1. Add the

...

  1. configuration files to the CLIENT component will make it available in the client tar ball downloaded from Ambari.

    Code Block
                    <component>
                    <name>SAMPLESRV_CLIENT</name>
                    <displayName>Sample Srv Client</displayName>
                    <category>CLIENT</category>
                    <cardinality>1+</cardinality>
                    <commandScript>
                        <script>scripts/sample_client.py</script>
                        <scriptType>PYTHON</scriptType>
                        <timeout>600</timeout>
                    </commandScript>
                    <configFiles>
                      <configFile>
                        <type>xml</type>
                        <fileName>test-config.xml</fileName>
                        <dictionaryName>test-config</dictionaryName>
                      </configFile>
                    </configFiles>
                </component>

  2. Create a directory for the configuration dictionary file SAMPLESRV/configuration.

    Code Block
    mkdir -p configuration
cd configuration

  3. Create the test-config.xml file. For example:

    Code Block
    <?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
  <property>
    <name>some.test.property</name>
    <value>this.is.the.default.value</value>
    <description>This is a test description.</description>
  </property>
  <property>
    <name>another.test.property</name>
    <value>5</value>
    <description>This is a second test description.</description>
  </property>
</configuration>

  4. There is an optional setting "configuration-dir".  Custom services should either not include the setting or should leave it as the default value "configuration".

     

    Code Block
    <configuration-dir>configuration</configuration-dir>
  5. Configuration dependencies can be included in the metainfo.xml in the a "configuration-dependencies" section.  This section can be added to the service as a whole or a particular component. One of the implications of this dependency is that whenever the config-type is updated, Ambari automatically marks the component or service as requiring restart.

    For example, HIVE defines a component level configuration dependencies for the HIVE_METASTORE component
    Code Block
          <component>
          <name>HIVE_METASTORE</name>
          <displayName>Hive Metastore</displayName>
          <category>MASTER</category>
          <cardinality>1</cardinality>
          <versionAdvertised>true</versionAdvertised>
          <reassignAllowed>true</reassignAllowed>
          <clientsToUpdateConfigs></clientsToUpdateConfigs>
... ...
          <configuration-dependencies>
            <config-type>hive-site</config-type>
          </configuration-dependencies>
        </component>

     

    HIVE also defines service level configuration dependencies.

    Code Block
         <configuration-dependencies>
        <config-type>core-site</config-type>
        <config-type>hive-log4j</config-type>
        <config-type>hive-exec-log4j</config-type>
        <config-type>hive-env</config-type>
        <config-type>hivemetastore-site.xml</config-type>
        <config-type>webhcat-site</config-type>
        <config-type>webhcat-env</config-type>
        <config-type>parquet-logging</config-type>
        <config-type>ranger-hive-plugin-properties</config-type>
        <config-type>ranger-hive-audit</config-type>
        <config-type>ranger-hive-policymgr-ssl</config-type>
        <config-type>ranger-hive-security</config-type>
        <config-type>mapred-site</config-type>
        <config-type>application.properties</config-type>
        <config-type>druid-common</config-type>
      </configuration-dependencies>

  6. Create a directory for the configuration dictionary file SAMPLESRV/configuration.

    Code Block
    mkdir -p configuration
cd configuration

  7. Create the test-config.xml file. For example:

    Code Block
    <?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
  <property>
    <name>some.test.property</name>
    <value>this.is.the.default.value</value>
    <description>This is a test description.</description>
 </property>
</configuration>