rancher-updater

ec.rancher-updater

This provides rancher-updater which is a commandline tool to do blue-green style deployments in Rancher.

Since version 0.4.0 rancher-updater will use the rancher api v2-beta and compose version 2 syntax.

Note that the temlates should be only services without the wrapping services: key in yaml. If this does not suit your use case PRs are welcome. :)

Installation

Make sure you have installed rancher-compose from Rancher. Then all you have to do is:

npm install -g rancher-updater

Usage

Rancher updater requires serveral assumptions for your Rancher setup. These are important to understand befor using Rancher updater. Also you need to be familiar with docker-compose and rancher-compose file format, since it will be used in addition to handlebars.

Commandline tool

# show help 
rancher-updater -h
 
# update webapp to version 5.0.3 build 4 
rancher-updater --url https://myrancher.example.com -s webapp -v 5.0.3 --build 4
 
# update worker to version 0.12.0-dev 
rancher-updater --url https://myrancher.example.com -s worker -v 0.12.0-dev -m service
 
# create app with version 0.0.1 
export RANCHER_URL=https://myrancher.example.com
rancher-updater -s app -v 0.0.1 -m initBalanced

Environments and Stacks

Rancher updater supports multiple environments and stacks.

For any environment you will need to get an access key (--access-key) and secret key (--secret-key) tied to a specific environment (--environment.

Stack names are tightly coupled to service names. Imagine you want to deploy a service ec-api.

• Stack name should be ec-api
• service name should be ec-api-$major-$minor-$patch[-build-$build].
  • for version 0.11.5-dev it would be ec-api-0-11-5-dev
  • for 5.1.0 build 5 ec-api-5-1-0-build-5.
• Docker image name and tag should be ec-api:$major.$minor.$patch
  • for version 0.11.5-devit would be ec-api:0.11.5-dev
  • for 5.1.0 build 5 it would be ec-api:5.1.0

The build number (--build) only applies to the service name (--service) and is not considered part of the docker image tag. Dots in the version (--version) are replaced by hyphens.

Modes

There are two main update modes, service and balanced.

• balanced

  This mode updates stacks with a load balancer in front of the main service. You can use this when ever you having an API. When updating a balanced stack the following steps are executed in order:

  • Check initial stack health
  • Check availability of new servie name
  • Check for old service
  • Print old config
  • Load and render templates
  • Create new service
  • Check health
  • Switch load balancer to new service
  • Check health (if this failes the balancer is switched back)
  • Delete old service

• service

  This is an service only mode without a load balancer. Use this when your service does not provide an API. Think of a worker service. When updating a service only stack the following steps are executed in order:

  • Check initial stack health
  • Check availability of new service name
  • Check for old service
  • Print old config
  • Load and render templates
  • Create new service
  • Check health
  • Delete old service

Each mode has its accompaning init mode, init and initBalanced. The init modes can be used to create the stack according to your configuration.

Templates

There are four templates which are used:

• balancer.docker.tpl.yml
• balancer.rancher.tpl.yml
• service.docker.tpl.yml
• service.rancher.tpl.yml

One for each docker-compose and rancher-compose file for the service and load balancer. Which one is which should be obvious.

This is a simple example of a service only template:

service.docker.tpl.yml

{{serviceName}}:
  environment:
    NODE_ENV: production
  labels:
    io.rancher.scheduler.affinity:container_label_soft_ne: io.rancher.stack_service.name=$${stack_name}/$${service_name}
    io.rancher.container.pull_image: always
  tty: true
  image: registry.example.com/{{service}}:{{version}}
  stdin_open: true

service.rancher.tpl.yml

{{serviceName}}:
  scale: {{scale}}

A more advanced example with load balancer is in ./examples.

When the templates are rendered rancher updater uses strict mode, so if your specify a variable which is not available in the command line parameters it will fail. See commandline tool description for additional info. As shown above you can use scale as variable. This defaults to 2 but will later be updated by the existing service which you want to upgrade.

TODOs

• build number and additional stack name: clean invalid characters.