Generate Ambari service configuration settings

[#1]

When changing Hadoop parameters via Ambari, Ambari will suggest other service configuration changes that it has detected. Is there a way to get a list of these suggestions without having to change an existing parameters? A REST interface would be very nice. David

[#2]

@David Robison

The component/service configuration dependencies are decided based on their "metainfo.xml" file settings.

For example Please take a look at:

# grep -A 11 'configuration-dependencies' /var/lib/ambari-server/resources/common-services/HDFS/2.1.0.2.0/metainfo.xml 
      <configuration-dependencies>
        <config-type>core-site</config-type>
        <config-type>hdfs-site</config-type>
        <config-type>hadoop-env</config-type>
        <config-type>hadoop-policy</config-type>
        <config-type>hdfs-log4j</config-type>
        <config-type>ranger-hdfs-plugin-properties</config-type>
        <config-type>ssl-client</config-type>
        <config-type>ssl-server</config-type>
        <config-type>ranger-hdfs-audit</config-type>
        <config-type>ranger-hdfs-policymgr-ssl</config-type>
        <config-type>ranger-hdfs-security</config-type>
      </configuration-dependencies>

Similarly now if you take a look at YARN metainfo.xml then you will find that it has <configuration-dependencies> on various HDFS configs like:

# grep -A 8 'configuration-dependencies' /var/lib/ambari-server/resources/common-services/YARN/2.1.0.2.0/metainfo.xml 
      <configuration-dependencies>
        <config-type>hdfs-site</config-type>
        <config-type>hadoop-env</config-type>
        <config-type>core-site</config-type>
        <config-type>mapred-site</config-type>
        <config-type>mapred-env</config-type>
        <config-type>ssl-client</config-type>
        <config-type>ssl-server</config-type>
      </configuration-dependencies>

For example you will see that YARN and MapReduce2 dependds on hdfs-site settings hence if you make any changes to HDFS config hdfs-site.xml then those respective components of YARN and MapReduce2 will need a restart.

.

For additional reference please refer to: https://cwiki.apache.org/confluence/display/AMBARI/Writing+metainfo.xml

[#3]

@David Robison

Additionally using Ambari API if you would like to findout what all comonents requires a Resstart (after you make changes to some XYZ service) then you can make use of the following API call:

We can use the Ambari APIs to find the stale configurations. (Notice: ?HostRoles/stale_configs=true)

http://erie1.example.com:8080/api/v1/clusters/ErieCluster/host_components?HostRoles/stale_configs=tr...

.

You can find more details on this in the following article:

https://community.hortonworks.com/articles/73272/how-to-find-and-fix-ambari-stale-configuration-usi....

[#4]

Thanks for the quick response. However, what I am actually looking for is a way to get the list of recommended service configuration changes generated by Ambari. For example, if I change an HDFS parameter and save the change, Ambari will respond with a list of parameters that are outside the recommended values and ask if I want to proceed with saving the configuration change. What I want is a way to get that list of recommendations without having to change and save a parameter change. Thanks, David