Docker Env Vars expanded with secrets content

README.md

Set secrets as env variables in docker

This script will read your secret file and set each line as an env variable in your container.

How to use it

I' assuming that you already has a entrypoint file in your Dockerfile. So now, you need to copy and paste the contents of set_env_secrets.sh to your entrypoint(you don't need the first line).

Now, you need to create a secret, the name could be whatever you like. I'm using the name of my application as a pattern for my secrets name. For this example, my secret name will be super-project and the content will be.

DB_HOST=mariadb
DB_DATABASE=mydatabase
DB_USERNAME=superuser
DB_PASSWORD=supersecretpassword

Then, in my compose file, I need to set that secret name. Like this:

application:
    image: IMAGENAME
    secrets:
      - super-project
    labels:
      - io.rancher.container.pull_image=always
    environment:
      **SECRET_NAME:super-project**

Now you just need to deploy your app and each line of that secret file will be a env variable for your application.

set_env_secrets.sh

#!/bin/sh

: ${ENV_SECRETS_DIR:=/run/secrets}

env_secret_debug()
{
    if [ ! -z "$ENV_SECRETS_DEBUG" ]; then
        echo -e "\033[1m$@\033[0m"
    fi
}

set_env_secrets() {
    secret_name=$SECRET_NAME
    secret_file_path="${ENV_SECRETS_DIR}/${secret_name}"
    env_secret_debug "Secret file: $secret_name"
    if [ -f "$secret_file_path" ]; then
        while IFS='' read -r line || [[ -n "$line" ]]; do
            export $line
        done < "$secret_file_path"
    else
        env_secret_debug "Secret file does not exist! $secret_name"
    fi

    if [ ! -z "$ENV_SECRETS_DEBUG" ]; then
        echo -e "\n\033[1mExpanded environment variables\033[0m"
        printenv
    fi
}

set_env_secrets

Hi! Line 21 is wrong. Should refer to $secret_name :)

@N0K0 just updated! Thank you!

Thanks for sharing this! I see your script uses [[ ]] and echo -e which is actually undefined in POSIX sh.

Thanks for the code!

Improvements i made:

• The variables secret_name and secret_file_path were declared as local variables within the set_env_secrets() function, reducing their scope and avoiding conflicts with other variables in the environment.
• The -n expression was used instead of ! -z to check if the ENV_SECRETS_DEBUG variable is defined and not empty.
• The declaration of the IFS variable was modified to IFS= read -r line || [ -n "$line" ], avoiding issues with interpreting values containing spaces and ensuring that the loop is executed even if the last line doesn't have a line break.

https://gist.github.com/marlluslustosa/0240f89e2d8ffa14c23ca77fcbda39a3