Docker secret is a feature in Docker Swarm Mode that allows you to securely store sensitive information, such as passwords or API keys, in a way that they can be accessed by your services without exposing them in the container’s stack configuration file or Docker Compose file.
Here’s a step by step guide:
1. Initialize Docker Swarm mode: Docker secrets are only available in Docker Swarm mode. You can initiate it by using the SQL command `docker swarm init` in the terminal.
1. Create a Docker Secret: Once the swarm mode is active, you can create a Docker Secret using the Docker CLI.
For instance, to create a secret for a password one could type:
`echo “my_password” | docker secret create my_password_secret -`This command specifies the ‘my_password’ string to create a secret named ‘my_password\_secret’.
1. Apply the Secret: This secret can now be applied to a service with the `docker service create` command.
For example:
`docker service create —name my_service —secret my_password_secret my_image`
In this example, the secret ‘my_password_secret’ is added to the service ‘my_service’. At runtime, Docker mounts a tmpfs filesystem to the path /run/secrets/my_secret in the containers that run the service tasks. The my_password_secret is placed in this path and can be used by the service without ever being exposed.
1. Access Secret inside the container: The secrets are now stored inside the container at the location /run/secrets/. If you have a secret named ‘my_secret’, you can access it at the location /run/secrets/my_secret. This can be done directly in your code.
1. Update/Rotate Secrets: If you need to rotate secrets, the Docker CLI also provides the `docker secret update` command:
`docker secret update my_password_secret -`1. Remove a secret: When a secret is no longer needed, it can be removed with `docker secret remove`.
`docker secret rm my_password_secret`Remember to replace “my_password”, “my_password_secret”, “my_service”, “my\_image” with your actual password, secret name, service name and image respectively.
Ensure that any sensitive information isn’t logged or output during the execution of an application using these secrets.
