Here's what I found. Data is flowing into ES indexes. I can change the
"masters_also_are_datanodes" property and it is reflected in the node.data
property in elasticsearch.yml.

Here's my search for this property in the source code. It is properly being
used int the ES mpack scripts afaik.

Targets
    Occurrences of 'masters_also_are_datanodes' in Directory
devprojects/metron/metron-deployment
Found Occurrences  (6 usages found)
    Unclassified occurrence  (5 usages found)
        metron-deployment  (2 usages found)
            metron-deployment/other-examples/manual-install  (1 usage found)
                Manual_Install_CentOS6.md  (1 usage found)
                    810 "masters_also_are_datanodes" to "true"
            metron-deployment/roles/ambari_config/vars  (1 usage found)
                single_node_vm.yml  (1 usage found)
                    104 masters_also_are_datanodes: "1"
        metron_mpack  (3 usages found)
            common-services.ELASTICSEARCH.2.3.3.configuration  (1 usage
found)
                elastic-site.xml  (1 usage found)
                    30 <name>masters_also_are_datanodes</name>
            common-services.ELASTICSEARCH.2.3.3.package.scripts  (1 usage
found)
                params.py  (1 usage found)
                    26 masters_also_are_datanodes =
config['configurations']['elastic-site']['masters_also_are_datanodes']
            common-services.ELASTICSEARCH.2.3.3.package.templates  (1 usage
found)
                elasticsearch.master.yaml.j2  (1 usage found)
                    36   *data: {{ masters_also_are_datanodes }}*
    Usage in string constants  (1 usage found)
        metron_mpack  (1 usage found)
            common-services.ELASTICSEARCH.2.3.3.package.scripts  (1 usage
found)
                params.py  (1 usage found)
                    26 *masters_also_are_datanodes =
config['configurations']['elastic-site']['masters_also_are_datanodes']*

It should be noted that regardless of the ES documentation, this seems to
work with a variety of values including "true" (with quotes) and 1 (without
quotes). When I set the value to garbage through Ambari, I see this in
/var/log/elasticsearch/metron.log
java.lang.IllegalArgumentException: value cannot be parsed to boolean
[ *true/1/on/yes
OR false/0/off/no* ]
        at
org.elasticsearch.common.Booleans.parseBooleanExact(Booleans.java:97)
        at
org.elasticsearch.cluster.node.DiscoveryNode.dataNode(DiscoveryNode.java:256)
        at
org.elasticsearch.cluster.node.DiscoveryNodes$Builder.build(DiscoveryNodes.java:659)
        at
org.elasticsearch.cluster.ClusterState$Builder.nodes(ClusterState.java:571)
        at
org.elasticsearch.cluster.service.InternalClusterService.doStart(InternalClusterService.java:205)
        at
org.elasticsearch.common.component.AbstractLifecycleComponent.start(AbstractLifecycleComponent.java:68)
        at org.elasticsearch.node.Node.start(Node.java:279)
        at org.elasticsearch.bootstrap.Bootstrap.start(Bootstrap.java:206)
        at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:272)
        at
org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)

Apparently, even yes/no will work! I tried it, and can confirm they work
with quotes. But surprisingly, this does NOT work if you pass true/false or
yes/no without quotes. In summary, here are the supported values:

   - 1
   - 0
   - "true"
   - "false"
   - "yes"
   - "no"

Mike
On Wed, Sep 13, 2017 at 2:17 PM, Matt Foley <[EMAIL PROTECTED]> wrote:
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