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Last updated: 9 Sep 2021

govuk-data-science-workshop: Loading environment variables

We use direnv to load environment variables, as these are only loaded when inside the project folder. This can prevent accidental conflicts with identically named variables.

Using direnv

To load the environment variables, first follow the direnv installation instructions, and make sure you have a .secrets file to store secrets and credentials. Then:

  1. Open your terminal;
  2. Navigate to the project folder; and
    • You should see the following message: 
      direnv: error .envrc is blocked. Run `direnv allow` to approve its content.
  3. Allow direnv. 
    direnv allow

You only need to do this once, and again each time .envrc and .secrets are modified.

Installing direnv

These instructions assume you are running on macOS with administrator privileges using a bash terminal. For other ways of installing direnv, and its shell hooks, consult the direnv documentation.

  1. Open your terminal;
  2. Install direnv using Homebrew; 
    brew install direnv
  3. Add the shell hooks to your .bash_profile; 
    echo 'eval "$(direnv hook bash)"' >> ~/.bash_profile
  4. Check that the shell hooks have been added correctly; and 
    cat ~/.bash_profile
    • This should display eval "$(direnv hook bash)"
  5. Restart your terminal.

Storing secrets and credentials

Secrets and credentials must be stored in the .secrets file. This file is not version-controlled, so no secrets should be committed to GitHub.

In your terminal navigate to the root folder, and create a .secrets file.

touch .secrets

Open this new .secrets file using your preferred text editor, and add any secrets as environmental variables. For example, to add a JSON credentials file for Google BigQuery, save the following changes to .secrets.

export GOOGLE_APPLICATION_CREDENTIALS="path/to/credentials.json"

Once complete, make sure the .secrets file has the following line uncommented out:

source_env ".secrets"

This ensures direnv loads the .secrets file using .envrc without version-controlling .secrets.