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Updating application instances

Application instances update is an important part of day to day job of a SaaS offering. KuberLogic supports instance upgrade by providing a new version of container image and allows to accomplish this task in a several ways.

Updating all application instances by changing docker-compose.yml

The simplest way to upgrade application instances is to update container image in docker-compose.yml and reconfigure KuberLogic.

Example:

services:
  demo:
    image: demo:v1 # change this to demo:v2 to upgrade applications to v2

This option has some drawbacks though:

  • All application instances will attempt to upgrade at the same time. This might result in hitting container registry limits or exhausting network
  • All application will go down if there are any issues with the new version. It will not be possible to test the upgrade.

Updating application instances by setting the version in KuberLogic

It is also possible to trigger an update of an individual instance by setting --version option (or version field in REST API call) when editing or creating the application instance. This, of course, requires docker-compose.yml changes to be made in advance and provided to KuberLogic (see installation guide):

services:
  demo:
    image: demo:{{ default .Version "v1" }} # when a `version` field is not set use v1

The snippet above uses Go template support for docker-compose.yml. To learn more see the configuration guide

Then, to change the instance version use command: kuberlogic edit --id <application instance id> --version <new version>