...
We have automated the process of creating the AMIs themselves, using the build_ami ansible role.
Outline
build_ami spins up a new ec2 image; installs software on it; takes a snapshot of the server and creates an ami for later use; and finally destroys the ec2 image. The buildvariable determines what software is installed.
Later on, the AMI’s id can be used in building an ec2 servers.
Software installed
Aside from packages and system_setup, which are run on all new machines, the following three optional software installation roles are run:
Ansible role | What it does | When it runs |
|---|---|---|
| Compiles and installs Ruby | If you pass |
| Compiles and installs | If you pass |
| Compiles and installs | If you pass |
Important files
File | Contents | |
|---|---|---|
build_ami.yml | Outline of the role | |
group_vars/ruby_ami | ami metadata (instance type, disk size, aws name and tags) | |
group_vars/ruby_image_ami | ami metadata | |
roles/dzi/vars/role_vars | Current vips version | |
roles/ruby/vars/role_vars | Current ruby version | |
roles/imagemagick/vars/role_vars | Current imagemagick version |
Example invocations
(we use the production key private-key here, as it will end up kind of permanently allowing ssh access to the machine, and we don’t want staging/test key to have access to production machines)
An AMI with ruby on top of ubuntu
...
(used for web servers, may be used for solr server although prob not necessary)
ansible-playook --ask-vault-pass build_ami.yml --private-key=~/.ssh/chf_prod.pem --extra-vars "build=ruby_ami"
An AMI with ruby and image utilities (vips and imagemagick) (used for jobs servers)
ansible-playook --ask-vault-pass build_ami.yml --private-key=~/.ssh/chf_prod.pem --extra-vars "build=ruby_image_ami"
Viewing created AMIs in the AWS console
The images are visible at: https://console.aws.amazon.com/ec2/v2/home?region=us-east-1#Images . Note in particular that the value of the AMI ID column in the table is used to tell Ansible which AMI to use when building ec2 machines. The variable used is ec2_image .
...
Finding or changing what AMI an ec2 instance is based on
...
Running grep ec2_image group_vars/* lists the AMIs our ec2 servers are based on.
...
While the comment is helpful, it’s possible to get this info by simply looking up the ID in the AWS console under EC2 > Images > AMIs.
To change an AMI that a given server role uses, find it’s variable file under group_vars, and change it to use the new AMI ID.
Obsolete AMI roles
There used to be a java_ami role we used for solr and fedora boxes, but is is no longer in use. ./group_vars/java_ami can be removed.