Default environment variables
How to create and manage default environment variables for your Release environments
Last updated
How to create and manage default environment variables for your Release environments
Last updated
Environment variables hold the environment-specific information that an application needs at runtime.
For instance, a web application deployed in a production environment has to know how to access the production database. The same application running in a staging environment would have to know about a staging database instead.
By storing configuration as environment variables instead of in code, you'll make your applications portable, secure, and easy to deploy on Release environments.
When you create a new application, Release generates a default environment variables file, based on your code.
For example, if your repository has a docker-compose.yml file, Release will populate the default environment variables for your new application based on the environment variables in that file.
If your repository does not have a docker-compose.yml file, you can create your Release application's default environment variables manually, by editing your application's settings.
To edit the default environment variables for an application, visit the application's App Settings page, then click the Environment Variables button.
This opens a YAML editor, which you can use to edit your default environment variables file.
A Release application's default environment variables file is formatted in YAML, and consists of three sections:
Hash
false
Array
true
Default environment variables for your app
Hash
false
Service-specific environment variables
Here's an example of a default environment variables file:
Environment variables consist of a key, a value, and an optional secret flag. Mark an environment variable as secret using secret=true. Secrets are encrypted at rest in a vault and hidden in the UI. You may also import secret environment variables from external secrets managers. See the instructions here for more on secrets.
key
String
True
The environment variable's name.
It is convention to use uppercase names for environment variables.
Example: DB_USERNAME
value
String or Null
True
The value for this environment variable.
Required if secret is false.
If secret is true, this field is optional, and Release defaults to the previously saved value if this field is omitted.
secret
Boolean
False
Here's an example of three environment variables:
When you create a new environment, Release uses the application's default environment variables file to generate an environment-specific environment variables file for your new environment.
Think of an application's default environment variables file as the blueprint for each new environment's environment variables.
Apart from the environment variables lifted from your docker-compose.yml, and the variables you created yourself, Release provides additional environment variables.
You can map Release's environment variables to your app's environment variable names so that you do not need to change your application's code when deploying on Release or elsewhere.
Environment variables provided by Release have names that start with RELEASE_.
Here's an overview of the variables provided by Release:
RELEASE_ACCOUNT_IDRelease account ID: Each Release account has a unique numerical identifier.
RELEASE_APP_NAMERelease application name: Each Release application has a unique string identifier.
RELEASE_BRANCH_NAMEGit branch: The name of the git branch from your repository deployed to this environment.
RELEASE_BUILD_IDRelease build ID: Each Release build has a unique numerical identifier.
RELEASE_CLOUD_PROVIDERCloud provider: The cloud provider that hosts this environment. For example, aws or gcp.
RELEASE_CLUSTER_REGIONCloud provider region: The cloud provider region for this environment. For example, us-west-2 or us-east-1.
RELEASE_COMMIT_SHAGit hash: The SHA hash of the git commit deployed in this environment. This refers to a commit in your repository.
RELEASE_COMMIT_SHORTShort git hash: The short hash of the git commit deployed in this environment. This refers to a commit in your repository.
RELEASE_CONTEXTRelease context: Refers to the Kubernetes context for this deployment.
RELEASE_DOMAINRelease domain: If you do not have a custom domain set up on your Release account, this will be rls.sh.
RELEASE_ENV_IDRelease environment ID: Each Release environment has a unique string identifier.
RELEASE_RANDOMNESSRelease random string: This short random string is used to create unique links.
Release also provides environment variables specific to each service in your environment.
When creating these variables, Release converts the service name to uppercase and prepends this to each service-specific environment variable's name.
For example, if you have two services, admin and frontend, Release provides environment variables as follows:
ADMIN_COMMIT_SHAShort git hash: The SHA hash of the git commit deployed for this service. This refers to a commit in your repository.
ADMIN_COMMIT_SHORTShort git hash: The short hash of the git commit deployed for this service. This refers to a commit in your repository.
ADMIN_INGRESS_HOSTIngress hostname: The hostname of the instance/load balancer for this service, accessible to the internet.
ADMIN_INGRESS_URLIngress URL: The public URL for this service.
FRONTEND_INGRESS_URL, FRONTEND_INGRESS_HOST etc.The equivalent environment variables are provided for the frontend service in this example.
mapping sectionYou can use the mapping section to map existing environment variables to new environment variables.
By mapping Release's environment variables to your app's environment variables, you do not need to reference Release-specific environment variable names in your code.
In the example below, your code expects an environment variable called AWS_REGION. Mapping allows you to pass RELEASE_CLUSTER_REGION to your application, adding its value to a new environment variable called AWS_REGION.
The mapping section also allows you to reference your app's environment variables. In the example below, REACT_APP_ADMIN_PATH gets its value from DEFAULT_ADMIN_PATH:
Release's mapping section allows you to create new environment variables through string interpolation.
In the example below, ADMIN_FULL_URL is created by concatenating ADMIN_INGRESS_URL and DEFAULT_ADMIN_PATH:
You can also provide default values if an environment variable is unset or empty.
In the example below, if MAYBE_EMPTY_BASE_URL does not exist, or is empty, the default https://example.com will take its place.
The syntax to indicate a default is based on parameter expansion in bash: ${parameter:-defaultvalue}, but unlike in bash, defaultvalue is interpreted as a string. defaultvalue can't reference an environment variable.
String interpolation and parameter expansion is limited to the mapping section of your environment variables YAML.
defaults sectionThe defaults section contains environment variables that are available to all services in an environment.
Here's an example of the defaults section:
services sectionUse the services section to define environment variables for specific services only. Each service in this section has one or more environment variables.
Here's an example of service-specific environment variables:
Maps to your app's environment variables
Value is and should be encrypted. Value will be hidden from Release UI.
Defaults to false.
