Variables Support

Cody supports the concept of variables. Variables allow you to set environment-specific variables. For example, development and production environments usually require the same code with different environmental variables.

Within the .cody/variables folder, you can create variable files and the variables defined in them are made available to your .cody DSL files.

.cody/project.rb
.cody/role.rb
.cody/schedule.rb

Structure

Here’s an example variables structure:

.cody
└── variables
    ├── base.rb
    ├── development.rb
    └── production.rb

Layering Support

The variable files are layered together. The base.rb and specific CODY_ENV variable file, like development.rb, are combined. An example helps explain. Let’s say you have these files:

base.rb:

@myvar = "base-value"

development.rb:

@myvar = "development-value"

production.rb:

@myvar = "production-value"

Then you can do this:

cody deploy # defaults to CODY_ENV=development

Since CODY_ENV=development is the default, this means @myvar = "development-value" is used.

If we want to use production values, then we can set CODY_ENV=production

CODY_ENV=production cody deploy

In this case, @myvar = "production-value" is used.

Now if we use CODY_ENV=staging

CODY_ENV=staging cody deploy

In this case, @myvar = "base-value" is used, since there is no staging.rb file.

Variables with --type Option

With codebuild, we can use a --type option to create additional codebuild projects under the .cody folder. Here’s a short example:

cody deploy --type deploy

The buildspec file it’ll use is here:

.cody/deploy/buildspec.yml

More info on the type option is here: Type Option.

Specific project type variables can be set. For example, let’s say you have a --type=deploy, the variable files that will be used are:

.cody/deploy/variables/base.rb
.cody/deploy/variables/development.rb

The type specific variable files override the top-level variable files. Type specific variable files get loaded last so they take the highest precedence. Example:

.cody/variables/base.rb - lowest precedence
.cody/variables/development.rb
.cody/deploy/variables/base.rb
.cody/deploy/variables/development.rb - highest precedence

The top-level variables files are also loaded because it is common to need variables that are available to all projects.

VPC and Migrations Example

A good variables example is running migrations. The migration tasks usually requires access to the VPC to connect to the database. However, the development and production resources can be on separate VPCs. Variables can help here:

.cody/variables/development.rb:

@vpc_config = { VpcId: "vpc-aaa", Subnets: ["subnet-aaa"], SecurityGroupIds: ["sg-111"]  }

.cody/variables/production.rb:

@vpc_config = { VpcId: "vpc-bbb", Subnets: ["subnet-bbb"], SecurityGroupIds: ["sg-222"]  }

You’ll use then @vpc_config variable in the project.rb.

.cody/project.rb:

github_url("https://github.com/tongueroo/demo-ufo")
linux_image("aws/codebuild/standard:4.0")
vpc_config @vpc_config

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