通过Ansible剧本部署应用程序而不会降低双方

Question

I'm using Ansible to deploy a Java web application. Deployment is quiet basic via Ansible running a Jenkins playbook, copying a jar-file to 2 separate application servers, called node-01a and node-01b, both behind an Amazon AWS load balancer.

Currently the deployment happens on both the node-01a and node-01b at the same time. What would be the easiest way to do this without both nodes going down at the same time?

Answer 1

You can use serial parameter for the task. See documentation . This is per play.

You can also specify 'degree of parallelism' at playbook level with command line param --forks=FORKS .

Probably not relevant for you but just for completeness let me also quote that :

Tasks are executed in order, one at a time, against all machines matched by the host pattern, before moving on to the next task.

Answer 2

I prefer to run rolling updates in a region by region basis using tags inside an Ansible playbook. You should always have your ELB servers in multiple zones, so using that principal is a good idea.

For any one server, lets suppose you have two tags - Application (Application:SuperApp as an example) and AvailabilityZone (AvailabilityZone:us-east-1a, AvailabilityZone:us-east-1d as examples). I do this to ensure I'm only running my script when both Application is set to SuperApp as well as AvailabilityZone is set to the appropriate zone when the script is run.

This then allows me to use an include script called 'doCoolStuff.yaml' like so when using the ec2.py inventory script:

- hosts: tag_Application_SuperApp:&tag_AvailabilityZone_us-east-1a
  gather_facts: False
  roles:
    - doCoolStuffRole
  tasks:
    - include: doCoolStuff.yaml

- hosts: tag_Application_SuperApp:&tag_AvailabilityZone_us-east-1d
  gather_facts: False
  roles:
    - doCoolStuffRole
  tasks:
    - include: doCoolStuff.yaml

Of course you need to do much more inside your doCoolStuffRole Role and your doCoolStuff.yaml include script, but the overall process is included in the above.