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ENVIRONMENT_VARIABLES.md

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Environment Variables

Environment variables are a typical way of configuring the different environments. These folders in this directory contain the environment variable files for the different services that are being deployed using the docker-compose.yml file.

About the Different Environments

There can be defined as many environments as desired under the config folder. By default, two different environment are included:

  • dev. Used for quick and fast deployments. Simply by following the initial instructions, a new local environment can be installed.
  • pro. Used for production. Note that production-ready variables are deliberately ignored in the folder. Thus, template files are used in this folder. Note that to avoid the credential leakage, production environment variables SHOULD be avoided in the platform.

Preferably, for bigger projects, additional environments may be created such as qa, testing, security or pre. Note that pro/*.env and pre/*.env files are ignored in the .gitignore file by default. These files SHOULD be added to the .gitignore to be sure that no additional file is being added to Docker by mistake.

The Usage of the .env File

The .env file in the main folder is not a standard environment variable file. Environment variables to be used within a container SHOULD not be defined here, since this file is used natively by Docker Compose to replace the values of the string within that file.

For example, the .env file can be used to tell docker compose which environment variables to use in the docker-compose.yml deployment without even changing the docker-compose.yml file and the name of the volumes and services that will be created.

The initial contents of this file make reference to the following strings:

  • APP_NAME. Sets the name for the application. Typically used in the logging methods.
  • ENVIRONMENT. Used to define the configuration to be loaded in the created containers. The docker-compose.yml file will try to locate environment files under the ./config/<ENVIRONMENT>/ folder. Note that you WILL need to update these files using the template files stored in the folder as a reference.

Alternative varuavkes may include, for example, access tokens to be able to reach private packages in Github.

  • GIT_ACCESS_TOKEN. Used when a private package from Github needs to be grabbed.

The docker-compose.yml file is already build with this approach in mind.

Environment Variables Usage

This section defines the environment variables that are being used in the service. Note that you will probably want to set in this file things like API keys, remote hosts and similar things.

  • LOG_LEVEL. Sets the logging level. It SHOULD be one of the following: DEBUG, INFO, WARNING or ERROR.

In Python scripts, note that the value of an environment variable named LOGGER_NAME can be grabbed as follows:

import os
VALUE = os.environ.get("LOGGER_NAME", "Logger")

Note that, using os.environ.get("<ENVIRONMENT_VARIABLE_NAME>", "<DEFAULT_VALUE") is often prefered to using os.environ["<ENVIRONMENT_VARIABLE_NAME>"] to set default values if they are not present and avoid the fact of having to deal with exceptions.