Application Autoscaler for SAP Business Technology Platform

Introduction

The application autoscaler service for SAP Business Technology Platform (SAP BTP) enables applications to automatically increase or decrease the number of instances of your app. These changes can be based on a schedule, or based on the value of a metric.

For more information on the application autoscaler, see Application Autoscaler Service document on the SAP Help Portal.

Binding the Application Autoscaler

The autoscaler service can be found on the Services Tab of the environment details page of your app’s environment.

Selecting the autoscaler service expands the entry to allow you to enter more details about the service you wish to bind, namely the Plan and the File which contains the configuration.

You need to specify the following:

• Plan – the plan you wish to use for the autoscaler, either Lite or Standard
• File – the file which contains the JSON to configure the autoscaler — more information, including the contents of the configuration file can be found in Application Autoscaler Service on the SAP Help Portal

Having provided this information, you can click Connect Services to connect the autoscaler to your app.

The structure of the configuration file can get quite complex, as described in the documentation of SAP website. Mendix therefore provides you with a tool to help you create the correct configuration.

Click Configurator to start the Autoscaler Configurator.

Using the Autoscaler Configurator

The Autoscaler Configurator provides a user-friendly interface to create the JSON file required to configure the application autoscaler.

There are three options available:

• Scheduled Scaling – the app is scaled according to a fixed schedule
• Dynamic Scaling – the app is scaled depending on the value of a metric
• Custom – a combination of both scheduled and dynamic scaling

The metrics you can use to trigger dynamic scaling are as follows:

• Memory consumed – monitors memory consumption in megabytes (memoryconsumed) or in percentage (memoryutil)
• CPU utilization in percentage
• Response time – monitors response time in milliseconds
• Throughput – monitors requests per seconds (RPS)

Open the Autoscaler Configurator by clicking the Configurator next to the autoscaler service in the Services tab of the Environment Details.

You first need to decide the sort of scaling you want to apply.

For Scaling, select one of the following:

• Schedule-based scaling – scaling based on a schedule, see the Scheduled Scaling section below
• Dynamic scaling – scaling based on the values of metrics, see Dynamic Scaling section below
• Custom – you need to set up both Dynamic Scaling and Scheduled Scaling as described in the sections below

You then need to set up the requested type of scaling. The sections below show a summary of the required information. For more information, see the Application Autoscaler Service documentation on the SAP Help Portal.

When you have added all the rules, you can do one of the following:

• Click Upload Configuration To Service to upload your autoscaler configuration directly to the autoscaler service.
• Click Download Configuration File to create a file containing the correct JSON for your autoscaler configuration; you can then upload this file as the configuration of your autoscaler service.

Scheduled Scaling

First, you need to choose whether to set up a Recurring Schedule or a schedule based on a Specific Date. You can also choose to set up a Custom combination of the two.

For all the types of schedule you need to set the following:

• Min Instances – minimum number of application instances that always run
• Max Instances – maximum number of application instances that can be provisioned as a part of the application scaling
• Timezone – the time zone in which to run the schedule

Other information will depend on the type of schedule you are making. You can add multiple rules and all the rules you have already set up in the Configurator will be displayed. For more information, see the sections below.

Specific Date

Click Add rule or Add another rule (if rules already exist) to add a new rule.

You need to enter the information requested on the following screen. A tooltip explains what needs to be entered for each value:

Click Add Rule to add this rule.

The new rule, and any existing rules will be shown in the Configurator as shown below.

You can collapse the view of existing rule by clicking - and expand it again with the +. You can also edit an existing rule by clicking Edit and delete an existing rule by clicking Delete.

Recurring Schedule

Click Add rule or Add another rule (if rules already exist) to add a new rule.

Select whether you want to add a rule for days of the week (for example, every Monday) or days of the month (for example, on the fourth day of every month). You can change this Schedule Type on the next screen if necessary.

You need to enter the information requested on the following screen. A tooltip explains what needs to be entered for each value:

Click Add Day to add the days to which this recurring schedule applies. If it is a rule for days of the week, day one is always Monday irrespective of any local conventions. You can add several days by using Add Day multiple times.

Click Add Rule to add this rule.

The new rule and any existing rules are shown in the configurator as shown below.

You can collapse the view of existing rule by clicking - and expand it again with the +. You can also edit an existing rule by clicking Edit and delete an existing rule by clicking Delete.

Dynamic Scaling

First, you need to set the following:

• Min Instances – minimum number of the application instances that always run
• Max Instances – maximum number of the application instances that can be provisioned as a part of the application scaling

Click Add rule or Add another rule (if rules already exist) to add a new rule.

You need to enter the information requested on the following screen. A tooltip explains what needs to be entered for each value:

Click Add Rule to add this rule.

The new rule, and any existing rules are shown in the configurator as shown below.

You can collapse the view of existing rule by clicking - and expand it again with the +. You can also edit an existing rule by clicking Edit and delete an existing rule by clicking Delete.