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Managing secret data

Co-op Cloud uses Docker Secrets to handle sensitive data, like database passwords and API keys, securely: docker secret ls

abra includes several commands to make it easier to manage secrets:

  • abra app <app> secret generate -- to auto-generate a single secret, or all secrets defined by the app, and store them in the Docker Swarm store,
  • abra app <app> secret insert -- to insert a single secret value from the Docker Swarm store,
  • abra app <app> secret delete -- to remove a single secret, or all secrets defined in the app, from the Docker Swarm store.

Secret versions

You will notice v1 in the example secret names above: like Docker Configs, Docker Secrets are immutable, which means that their values can't be changed after they're set. To accommodate this, Co-op Cloud uses the established convention of "secret versions". Every time you change (rotate) a secret, you will insert it as a new version.

Because secret versions are managed per-instance by the people deploying their apps, secret versions are stored in the .env file for each app:

find -L ~/.abra/servers/ -name '*.env' -print0 | xargs -0 grep -h SECRET

If you try and add a secret version which already exists, Docker will helpfully complain:

abra app example_wordpress secret insert db_password v1 foobar
Error response from daemon: rpc error: code = AlreadyExists desc = secret example_wordpress_db_password_v1 already exists

By default, new app instances will look for v1 secrets.

Generating secrets automatically

You can generate secrets in one of two ways:

  1. While running abra app new <type>, by passing --secrets
  2. At any point once an app instance is defined, by running abra app <app> secret generate ... (see abra help secret generate for full options)

How are secrets generated?

Depending on how the app is configured, you will require the pwqgen (from passwdqc) and pwgen binaries by default, although you can specify your own password-generation app when running abra <app> secret generate by providing the <cmd> argument.

Inserting secrets manually

For third-party API tokens, like OAuth client secrets, or keys for services like Mailgun, you will be storing values you already have as the appropriately-named Docker secrets. abra provides a convenient interface to the underlying docker secret create command:

abra app example_wordpress secret insert db_password v2 "your-secret-here"

Rotating a secret

So, given how secret versions work, here's how you change a secret:

  1. Find out the current version number of the secret, e.g. by running abra app example_wordpress config, and choose a new one. Let's assume it's currently v1, so by convention the new secret will be v2.
  2. Generate or insert the new secret:
    abra app example_wordpress secret generate db_password v2
    abra app example_wordpress secret insert db_password v2 "foobar"
  3. Edit the app configuration to change which secret version the app will use:
    abra app example_wordpress config
  4. Re-reploy the app with the new secret version:
    abra app example_wordpress deploy

Storing secrets in pass

The Co-op Cloud authors use the UNIX pass tool to share sensitive data, including Co-op Cloud secrets, and abra <app> secret... commands include a --pass option to automatically manage generated / inserted secrets:

# Store generated secrets in `pass`:
abra app new wordpress --secrets --pass
abra app example_wordpress secret generate --all --pass
# Store inserted secret in `pass`:
abra app example_wordpress secret insert db_password v2 --pass
# Remove secrets from Docker, and `pass`:
abra app example_wordpress secret rm --all --pass

This functionality currently relies on our specific pass structure; patches to make that configurable are very welcome!

What makes secrets secure?