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https://issues.apache.org/jira/browse/WHIRR-693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13571484#comment-13571484
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Tom White commented on WHIRR-693:
---------------------------------
This sounds like a useful addition. It looks like a compatible change - so old
recipes will still work.
Paul, are you willing to provide a patch for this?
> Control order of actions with waves of whirr.instance-templates
> ---------------------------------------------------------------
>
> Key: WHIRR-693
> URL: https://issues.apache.org/jira/browse/WHIRR-693
> Project: Whirr
> Issue Type: Bug
> Components: core
> Reporter: Paul Baclace
> Priority: Critical
>
> A cluster can be specified with "waves" by supporting an optional suffix on
> whirr.instance-templates property in order to provide *running* base-level
> services (like ZK or a master-master mysql) to another layer of services
> during the configuration phase. This enables storing cluster-wide information
> in zookeeper or doing db creation beforehand.
> An example of a two "wave" (avoiding "phase" which already has a meaning)
> cluster:
> whirr.instance-templates.0=1 zookeeper, 2 zookeeper, 4 noop
> The .0 templates run like normal during "whirr launch-cluster" and then,
> during the same Whirr run, the .1 template is applied as a modification of
> the same cluster so that new host instances are not allocated:
> whirr.instance-templates.1=1 my-master, 2 my-gateway, 4 my-worker
> In the second wave, instance provisioning is inhibited, the
> instance-templates must have the same number of commas and same sequence of
> leading numbers, and a role is only allowed to appear in one wave.
> Here is another example:
> whirr.instance-templates.0=1 mysql-master+zookeeper, 1
> mysql-master+zookeeper,4 noop
> whirr.instance-templates.1=1 hadoop-namenode+hadoop-jobtracker, 1
> hbase-master+hadoop-secondarynn,4
> hadoop-tasktracker+hadoop-datanode+hbase-regionserver
> In the first wave, the two mysql-masters form a multi-master ensemble which
> keeps state information about the setup in the Whirr process (much like
> ZooKeeperCluster.getHosts(cluster) informs services/hbase of the quorum).
> In the second wave, nodes are not allocated
> (BootstrapClusterAction.doAction() is inhibited if instances already exist),
> but all phases for LaunchClusterCommand, including beforeBootstrap() and
> afterBootstrap() callbacks, are executed. If other
> whirr.cli.command.*Command are run, they would see a combined
> whirr.instance-templates that works like normal.
> Obviously, there would be no reason to limit this to 2 waves, but I do not
> expect more than 10 waves to be useful, so the pattern could enable a suffix
> of "\.[0-9]".
> Instead of WHIRR-221 which aims to specify a single global order for service
> startup, the wave format has the advantage that it relies on the implicit
> synchronization barriers at phases already supported by Whirr, the phases
> still run actions within phases in parallel, and state generated by a wave is
> available to later waves.
> Conceptually, this merely splits the whirr.instance-templates into waves of
> (bootstrap,install,configure,start). If no .[0-9] suffixes are present, then
> Whirr would behave just like normal.
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