Ways to use ENV variables

In this section, we'll explain how to use environment variables from the .env.tpl file in both bolt.yaml and bolt.service.yaml files.

Bolt keeps .env.tpl file in your project's root and against each of your bolt services. This is because, you can use environment variables in your bolt.service.yaml files and bolt.yaml's ingress attribute.

We'll cover two main aspects:

Using Environment Variables in bolt.yaml for bolt Ingress Attributes
Using Environment Variables in bolt.service.yaml for bolt Service Configuration

Using Environment Variables in bolt.yaml for Ingress Attributes

The bolt.yaml file contains configuration for your project, services and ingress. In the ingress section, you can define domain-specific routes to forward incoming requests to the appropriate service. To make these configurations more dynamic and configurable, you can use environment variables from the .env.tpl file. Here's how:

Defining Environment Variables in .env.tpl

In your project's root directory, you have a file named .env.tpl. This file serves as a template for defining environment variables that can be used in other configuration files. For the ingress attribute in bolt.yaml, you can define the environment variables like this:

# .env.tpl
TODOONE_APP_PORT=8001
TODOTWO_APP_PORT=8002

Using Environment Variables in bolt.yaml

In bolt.yaml, you have defined ingress configurations for two domains (todo-one.local.gluestack.app and todo-two.local.gluestack.app). You can use the previously defined environment variables for the proxy_pass attribute like this:

# bolt.yaml
envfile: .env.tpl
project_id: '1689657879944'
project_name: two-next-apps
services:
  todoone:
    path: ./services/todo-one
  todotwo:
    path: ./services/todo-two
ingress:
  - domain: todo-one.local.gluestack.app
    port: ${TODOONE_APP_PORT} # Use the environment variable here
    options:
      - location: /
        rewrite_key: ^/(.*)
        rewrite_value: /$1
        proxy_pass: http://localhost:${TODOONE_APP_PORT} # Use the environment variable here
  - domain: todo-two.local.gluestack.app
    port: ${TODOTWO_APP_PORT} # Use the environment variable here
    options:
      - location: /
        rewrite_key: ^/(.*)
        rewrite_value: /$1
        proxy_pass: http://localhost:${TODOTWO_APP_PORT} # Use the environment variable here

By using ${SERVICENAME_VARIABLENAME}, the values for port and proxy_pass attributes will be dynamically replaced with the values from the .env.tpl file. This allows you to change these values easily without modifying the bolt.yaml file directly.

Using Environment Variables in bolt.service.yaml for Service Configuration

Each service in your project has its own bolt.service.yaml file, which contains configuration details specific to that service. You can also use environment variables from .env.tpl in these service-specific configuration files.

Defining Service-Specific Environment Variables in .env.tpl

In the .env.tpl file, you can also define environment variables specific to each service. For example:

For todo-one:

# services/todo-one/.env.tpl
APP_PORT=4001
LOCAL_BUILD_COMMAND="npm run dev"
DOCKER_BUILD_FILEPATH=./run.Dockerfile

For todo-two:

# services/todo-two/.env.tpl
APP_PORT=4002
LOCAL_BUILD_COMMAND="npm run dev"
DOCKER_BUILD_FILEPATH=./run.Dockerfile

Using Environment Variables in bolt.service.yaml

In the bolt.service.yaml files for todo-one and todo-two services, you can use the environment variables as follows:

For todo-one:

# services/todo-one/bolt.service.yaml
container_name: todoone
stateless: true
default_service_runner: docker
supported_service_runners:
  - local
  - docker
service_runners:
  local:
    envfile: .env
    build: npm install && npm run dev
    ports:
      - ${APP_PORT}:4001
  docker:
    envfile: .env
    build: ./run.Dockerfile
    ports:
      - ${APP_PORT}:4001
    volumes:
      - ./services/todo-one:/app/todo-one
      - /app/todo-one/node_modules

For todo-two:

# services/todo-two/bolt.service.yaml
container_name: todotwo
stateless: true
default_service_runner: docker
supported_service_runners:
  - local
  - docker
service_runners:
  local:
    envfile: .env
    build: ${LOCAL_BUILD_COMMAND} # Use the environment variable here
    ports:
      - ${APP_PORT}:4002
  docker:
    envfile: .env
    build: ${DOCKER_BUILD_FILEPATH} # Use the environment variable here
    ports:
      - ${APP_PORT}:4002
    volumes:
      - ./services/todo-two:/app/todo-two
      - /app/todo-two/node_modules

By using ${VARIABLE_NAME}, the values for build and other attributes will be dynamically replaced with the values from the .env.tpl file specific to each service. This makes your service configurations more flexible and allows you to customize each service separately.

In summary, using environment variables from the .env.tpl file in your bolt.yaml and bolt.service.yaml files allows you to keep your configurations separate from your code and makes it easier to manage different environments and settings for your project and services.

We have put down a tutorial to help you get started and give you a basic example of how env management really works and how to use it in a project containing two services (ie. NextJS apps) using Bolt!

Tutorials: Two Next Apps & Ways to use ENV variables in Bolt Services & Bolt Ingress

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