Jonathan Hurley created AMBARI-19448:
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Summary: Role Command Order For HOU Is Different For Some
Components
Key: AMBARI-19448
URL: https://issues.apache.org/jira/browse/AMBARI-19448
Project: Ambari
Issue Type: Bug
Components: ambari-server
Affects Versions: 2.5.0
Reporter: Jonathan Hurley
Assignee: Jonathan Hurley
Priority: Critical
Fix For: 2.5.0
As of AMBARI-19435, HOU now uses the role command ordering to determine how to
start components on a host. This is because some components (such as
NodeManager and DataNode) require their masters to be online first in order to
register correctly. When co-located on the same host, masters and slaves must
be started in the correct order.
However, some ordering defined on the stack will not work for HOU. For example,
the stack doesn't enforce that NameNode start before DataNode. This is because
in a normal start command, the DataNode can wait for up to 30 minutes for the
NameNode to come online. During an upgrade, the upgrade logic waits to ensure
that the DataNode is online and registered before moving on. Since the role
ordering allows DataNode to start first, this start always fails during an
upgrade.
There are several ways of implementing this:
-
{code:title="Adding a new section to existing role_command_order.json}
{
"_comment" : "Record format:",
"_comment" : "blockedRole-blockedCommand: [blockerRole1-blockerCommand1 ... ",
"general_deps" : {
...
},
"host_ordered_upgrade" : {
"DATANODE-START": ["NAMENODE-START"]
}
{code}
-
{code:title="JSON directly in the upgrade pack}
<group xsi:type="host-order" name="HOST_ORDER" title="Upgrade All Hosts">
<skippable>true</skippable>
<role-command-order>
<section name="general_deps">
"DATANODE-START": ["NAMENODE-START"]
</section>
</role-command-order>
</group>
{code}
- {code:title="A separate JSON file to keep the JSON out of the upgrade pack
and the stack role_command_order.json}
<group xsi:type="host-order" name="HOST_ORDER" title="Upgrade All Hosts">
<skippable>true</skippable>
<role-command-order file="host-upgrades-role-command-order.json/>
</group>
{code}
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