Introduction

Blueprints are ordinary stack configuration, but unlike stacks, can't be deployed. Stacks can inherit configuration from them and also override parts or all of the inherited configuration. Blueprints can help you to reduce repetitive configuration.

Blueprints can contain the same properties as ordinary stacks. You place blueprint files to blueprints directory or its subdirectories. Each blueprint file must have .yml extension.

In stack configuration, you use blueprint property to specify from which blueprint the stack inherits its configuration.

Example

Our project looks like this:

.
├─ stacks
│  ├─ frontend.yml
│  ├─ backend.yml
│  ├─ operative-database.yml
│  └─ reporting-database.yml
├─ templates
│  ├─ application-template.yml
│  ├─ database-template.yml
│  └─ custom-database-template.yml
└─ blueprints
   ├─ application.yml
   └─ database.yml

We have four stacks and two blueprints. Let's look at the blueprints first.

blueprints/application.yml is blueprint for applications. It doesn't specify any parameters, so any stack using it, must provide values for the parameters found in templates/application-template.yml template file.

blueprints/application.yml

template: application-template.yml
regions: eu-west-1

templates/application-template.yml is template used by blueprints/application.yml blueprint.

templates/application-template.yml

Parameters:
  Environment:
    Type: String
    Description: Application environment
  Name:
    Type: String
    Description: Application name
  DockerImage:
    Type: String
    Description: Application docker image

Resources:
  # ...Resources omitted for brevity 

Our project has two application stacks: frontend.yml and backend.yml. They both use blueprints/application.yml and provide value for its parameters.

stacks/frontend.yml

blueprint: application.yml
paramters:
  Environment: dev
  Name: Frontend App
  DockerImage: frontend:1.0.0

stacks/backend.yml

blueprint: application.yml
paramters:
  Environment: dev
  Name: Backend App
  DockerImage: backend:2.0.0

blueprints/database.yml is blueprint for databases. It provides some default values for its parameters.

blueprints/database.yml

template: database-template.yml
regions: eu-west-1
parameters:
  InstanceClass: db.m4.large
  AllocatedStorage: 50
  Engine: mariadb
  EngineVersion: 10.6.8

templates/database-template.yml is template used by blueprints/application.yml blueprint.

templates/database-template.yml

Parameters:
  Environment:
    Type: String
    Description: Database environment
  InstanceClass:
    Type: String
    Description: Database instance class
  AllocatedStorage:
    Type: Number
    Description: Database allocated storage
  Engine:
    Type: String
    Description: Database engine
  EngineVersion:
    Type: String
    Description: Database engine version
    
Resources:
  # ...Resources omitted for brevity 

templates/custom-database-template.yml is some customized database template with fewer parameters.

templates/custom-database-template.yml

Parameters:
  Environment:
    Type: String
    Description: Database environment
  AllocatedStorage:
    Type: Number
    Description: Database allocated storage
    
Resources:
  # ...Resources omitted for brevity 

Finally, there are two database stacks: operative-database.yml and reporting-database.yml. They both use blueprints/database.yml but the latter uses an alternative template.

stacks/operative-database.yml

blueprint: database.yml
paramters:
  Environment: dev
  InstanceClass: db.m4.medium
  AllocatedStorage: 25

stacks/reporting-database.yml

blueprint: database.yml
template: custom-database-template.yml
paramters:
  Environment: dev
  AllocatedStorage: 100