Distribution¶

Manages scaling of applications. Distribution is responsible for creating and removing application instances. It is identified by id.

Elements¶

id

Distribution id.

applicationId

Id of application that will be managed by the distribution.

numberOfInstances

Number of application-instances that need to be running.

checkIfNodeCanAcceptNewApplicationInstanceScriptId

Id of script that checks if node can accept new application-instances. If the value is null, node's script or default script will be used.

selectNodeForNewApplicationInstanceScriptId

Id of script that selects node for new application-instance. If the value is null, the default script will be used.

selectApplicationInstanceToRemoveScriptId

Id of script that selects node that will have the application-instance removed. If the value is null, the default script will be used.

Usage¶

Distribution is highly recommended for production environment. It can automatically handle amount of instances that can be changed at any moment.

There is a few options to create distribution

Create distribution using CLI¶

 onteoncli distribution create --application-id=<application-id> --number-of-instances=<number-of-application-instances>

Create distribution using CLI - with distribution file.¶

First, you need to create yaml file that describes distribution. Example file:

 application: <application-id>
 numberOfInstances: <number-of-application-instances>
 type: <type>
 scripts:
   checkIfNodeCanAcceptNewApplicationInstance: <name-of-script OPTIONAL>
   selectNodeForNewApplicationInstance: <name-of-script OPTIONAL>
   selectApplicationInstanceToRemove: <name-of-script OPTIONAL>

Then, execute command:

  onteoncli distribution create-from-file <distribution-file>

Create distribution using http API¶

If you want to create distribution via http api, you can send POST request to /onteon-api-access/api/distributions.

Modifying distribution¶

You can always modify you distribution. E.q. you can easily change the number of instances by executing onteoncli distribution set-number-of-instances <id> <newNumberOfInstances>. Environment will be updated during the next rescheduling. You can set when the rescheduling job should start here, by specifying cron expression.

Distributing instances¶

Scripts are used to decide where specific application instance should be located or which one should be removed. If you do not specify scripts, the distribution will use the default scripts.