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Automatically scale workloads by resource utilization metrics and cron

Prerequisite#

Make sure auto-scaler trait controller is installed in your cluster

Install auto-scaler trait controller with helm

  1. Add helm chart repo for autoscaler trait

    helm repo add oam.catalog http://oam.dev/catalog/
  2. Update the chart repo

    helm repo update
  3. Install autoscaler trait controller

    helm install --create-namespace -n vela-system autoscalertrait oam.catalog/autoscalertrait

Autoscale depends on metrics server, please enable it in your Kubernetes cluster at the beginning.

Note: autoscale is one of the extension capabilities installed from cap center, please install it if you can't find it in vela traits.

Setting cron auto-scaling policy#

Introduce how to automatically scale workloads by cron.

  1. Prepare Appfile

    name: testapp
    services:
    express-server:
    # this image will be used in both build and deploy steps
    image: oamdev/testapp:v1
    cmd: ["node", "server.js"]
    port: 8080
    autoscale:
    min: 1
    max: 4
    cron:
    startAt: "14:00"
    duration: "2h"
    days: "Monday, Thursday"
    replicas: 2
    timezone: "America/Los_Angeles"

The full specification of autoscale could show up by $ vela show autoscale.

  1. Deploy an application

    $ vela up
    Parsing vela.yaml ...
    Loading templates ...
    Rendering configs for service (express-server)...
    Writing deploy config to (.vela/deploy.yaml)
    Applying deploy configs ...
    Checking if app has been deployed...
    App has not been deployed, creating a new deployment...
    ✅ App has been deployed 🚀🚀🚀
    Port forward: vela port-forward testapp
    SSH: vela exec testapp
    Logging: vela logs testapp
    App status: vela status testapp
    Service status: vela status testapp --svc express-server
  2. Check the replicas and wait for the scaling to take effect

    Check the replicas of the application, there is one replica.

    $ vela status testapp
    About:
    Name: testapp
    Namespace: default
    Created at: 2020-11-05 17:09:02.426632 +0800 CST
    Updated at: 2020-11-05 17:09:02.426632 +0800 CST
    Services:
    - Name: express-server
    Type: webservice
    HEALTHY Ready: 1/1
    Traits:
    - ✅ autoscale: type: cron replicas(min/max/current): 1/4/1
    Last Deployment:
    Created at: 2020-11-05 17:09:03 +0800 CST
    Updated at: 2020-11-05T17:09:02+08:00

    Wait till the time clocks startAt, and check again. The replicas become to two, which is specified as replicas in vela.yaml.

    $ vela status testapp
    About:
    Name: testapp
    Namespace: default
    Created at: 2020-11-10 10:18:59.498079 +0800 CST
    Updated at: 2020-11-10 10:18:59.49808 +0800 CST
    Services:
    - Name: express-server
    Type: webservice
    HEALTHY Ready: 2/2
    Traits:
    - ✅ autoscale: type: cron replicas(min/max/current): 1/4/2
    Last Deployment:
    Created at: 2020-11-10 10:18:59 +0800 CST
    Updated at: 2020-11-10T10:18:59+08:00

    Wait after the period ends, the replicas will be one eventually.

Setting auto-scaling policy of CPU resource utilization#

Introduce how to automatically scale workloads by CPU resource utilization.

  1. Prepare Appfile

    Modify vela.yaml as below. We add field services.express-server.cpu and change the auto-scaling policy from cron to cpu utilization by updating filed services.express-server.autoscale.

    name: testapp
    services:
    express-server:
    image: oamdev/testapp:v1
    cmd: ["node", "server.js"]
    port: 8080
    cpu: "0.01"
    autoscale:
    min: 1
    max: 5
    cpuPercent: 10
  2. Deploy an application

    $ vela up
  3. Expose the service entrypoint of the application

    $ vela port-forward helloworld 80
    Forwarding from 127.0.0.1:80 -> 80
    Forwarding from [::1]:80 -> 80
    Forward successfully! Opening browser ...
    Handling connection for 80
    Handling connection for 80
    Handling connection for 80
    Handling connection for 80

    On your macOS, you might need to add sudo ahead of the command.

  4. Monitor the replicas changing

    Continue to monitor the replicas changing when the application becomes overloaded. You can use Apache HTTP server benchmarking tool ab to mock many requests to the application.

    $ ab -n 10000 -c 200 http://127.0.0.1/
    This is ApacheBench, Version 2.3 <$Revision: 1843412 $>
    Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
    Licensed to The Apache Software Foundation, http://www.apache.org/
    Benchmarking 127.0.0.1 (be patient)
    Completed 1000 requests

    The replicas gradually increase from one to four.

    $ vela status helloworld --svc frontend
    About:
    Name: helloworld
    Namespace: default
    Created at: 2020-11-05 20:07:21.830118 +0800 CST
    Updated at: 2020-11-05 20:50:42.664725 +0800 CST
    Services:
    - Name: frontend
    Type: webservice
    HEALTHY Ready: 1/1
    Traits:
    - ✅ autoscale: type: cpu cpu-utilization(target/current): 5%/10% replicas(min/max/current): 1/5/2
    Last Deployment:
    Created at: 2020-11-05 20:07:23 +0800 CST
    Updated at: 2020-11-05T20:50:42+08:00
    $ vela status helloworld --svc frontend
    About:
    Name: helloworld
    Namespace: default
    Created at: 2020-11-05 20:07:21.830118 +0800 CST
    Updated at: 2020-11-05 20:50:42.664725 +0800 CST
    Services:
    - Name: frontend
    Type: webservice
    HEALTHY Ready: 1/1
    Traits:
    - ✅ autoscale: type: cpu cpu-utilization(target/current): 5%/14% replicas(min/max/current): 1/5/4
    Last Deployment:
    Created at: 2020-11-05 20:07:23 +0800 CST
    Updated at: 2020-11-05T20:50:42+08:00

    Stop ab tool, and the replicas will decrease to one eventually.

Last updated on by kubevela-bot