App Deploy Ansible Playbook

Code Structure

.
├── inventory
│   ├── group_vars
│   │   ├── dev.yml
│   │   └── staging.yml
│   ├── dev.yml
│   └── staging.yml
├── roles
│   └── deploy_app
│       ├── defaults
│       │   └── main.yml
│       ├── tasks
│       │   ├── deploy.yml
│       │   └── main.yml
│       ├── templates
│       │   └── compose.yaml.tmpl
│       └── vars
│           └── main.yml
├── deploy_app.yml
└── README.md

Requirements

• Python 3.8 or higher on the Ansible host
• ansible_core 2.15.6 or higher on the Ansible host
• Docker Swarm nodes on the Ansible targets (To have multiple replicas)

Playbook Functions

• Prepares the Swarm OS to run the services
• Checks if the host has enough resources to run the services (Using service requirements settings and resource reservations)
• Deploys the Docker Compose configuration file
• Starts the service up
• Checks the service availability

Usage

• New services can be added and individually configured in the roles/deploy_app/vars/main.yml file
• All default environment related variables are set in roles/deploy_app/vars/main.yml file, and they can be overwritten in the respective group_var files
• New hosts can be added to environment hosts files dev or staging or other groups can be created
• New environments can be added by adding a new host group and corresponding group_vars file

Run the playbook against all environments:

ansible-playbook -i inventory deploy_app.yml

Or limit the run to certain environment (dev/stg)

ansible-playbook -i inventory/{environment}.yml deploy_app.yml

Design Considerations

• The service configuration settings are passed as environmental variables to the containers
• The Docker Compose configuration file is generated from template using the configuration taken from the role
• The template only manages currently used functions, is another section has to be added, the template should be amended

Production Considerations

• Never configure sensitive data like username/password from plain text setting
  • Use Ansible Vault to encrypt the values (Still going to be stored plain text on the Swarm host and in the container's environment variables)
  • Best to use an external secret store, like HashiCorp Vault