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2019-03-28

{:shortdesc: .shortdesc} {:new_window: target="_blank"} {:codeblock: .codeblock} {:pre: .pre} {:screen: .screen} {:tip: .tip}

Autoscaling applications

{: #autoscale_cloud_foundry_apps}

{{site.data.keyword.Bluemix}} has a built-in autoscaling support for Cloud Foundry applications to adjust application instance number automatically through

  • Dynamic scaling based on application performance metrics.
  • Scheduled scaling based on time.

This capability is offered based on Cloud Foundry open source project App-Autoscaler. Refer to user guide to get started.

Managing autoscaling through CLI

You can use App Autoscaler command-line interface plugin (aka AutoScaler CLI) to manage policy, query metrics and scaling history.

Installing AutoScaler CLI

Use the following command to install AutoScaler CLI which is a plugin of Cloud Foundry CLI.

cf install-plugin -r CF-Community app-autoscaler-plugin

{:codeblock}

The same command can be used to update AutoScaler CLI plugin to the latest version if you have a prior installation.

Using the AutoScaler CLI

If you already logged in to a Cloud Foundry environment on {{site.data.keyword.Bluemix}} and have applications running in your space as described in deploying apps guide, follow steps below to create a scaling policy for your application, and query metrics and scaling history.

  • (optional) Confirm the App-Autoscaler API endpoint is set correctly by default.

    If Cloud Foundry API endpoint is presented as api.<DOMAIN>, the App-Autoscaler API endpoint should be autoscaler.<DOMAIN>.
    Use the command below to check the App-Autoscaler API endpoint setting.

    cf asa

    {:codeblock}

    If the App-Autoscaler API endpoint is incorrect, you need to reset it with command:

    cf asa autoscaler.<DOMAIN>

    {:codeblock}

  • Create a policy JSON file on your local machine.

    cat > <YOUR_POLICY_FILE> << EOF
{
        "instance_min_count": 1,
        "instance_max_count": 5,
        "scaling_rules": [
                {
                        "metric_type": "memoryutil",
                        "breach_duration_secs": 120,
                        "threshold": 80,
                        "operator": ">=",
                        "cool_down_secs": 120,
                        "adjustment": "+1"
                },
                {
                        "metric_type": "memoryutil",
                        "breach_duration_secs": 120,
                        "threshold": 10,
                        "operator": "<",
                        "cool_down_secs": 120,
                        "adjustment": "-1"
                }
        ]
}
EOF

    {:codeblock}

    The policy above is used to trigger scaling based on memory utilization when the defined threshold is breached for at least 120 seconds. Refer to Cloud Foundry App-Autoscaler user guide for how to create your own autoscaling policy.

  • Attach the policy to your application

    cf aasp <YOUR_APP> <YOUR_POLICY_FILE>

    {:codeblock}

  • (optional) Furthermore, you can query the most recent aggregated metrics of your application. App-Autoscaler supports multiple metric types, but only the metrics you defined in your policy could be retrieved, i.e. memoryutil in above example.

    cf asm <YOUR_APP> <METRIC_TYPE> --desc

    {:codeblock}

  • (optional) Use the command below to query scaling history:

    cf ash <YOUR_APP> --desc

    {:codeblock}

    Refer to Cloud Foundry App Autoscaler CLI plugin guide for more options to use the command line.

Managing Autoscaling through the Stratos console

Besides the command line interface, you can also manage autoscaling settings through Stratos console .

If you have installed stratos on your {{site.data.keyword.cfee_full}} (CFEE), go to the "Auto scaling" tab in the application dashboard to see an overview of the auto-scaling policy and most recent scaling events. Click any of the icons in any of the tiles to launch the policy editor and edit the policy.

If no auto-scaling policy is defined, the the overview page will have no information. Click Create policy to launch the policy editor and create a policy.

We recommend to go through the Cloud Foundry App-Autoscaler User Guide to understand the basic concepts to set an auto-scaling policy properly.

Metric Statistics

Once you have defined a policy based on one or more selected metric types, you can view the latest metric values, and metrics history in the last 30 minutes.

Note: Metrics represent data averaged over all the application instances, not raw data from each application instance.

Scaling History

the History tab in the policy editor shows scaling actions were taken on your application triggered by the auto-scaling policy. It also shows any error messages resulting from scaling failures. You can query scaling history during the past 30 days.