Alright, let's get started with installing HashiCorp Vault. You can follow the official installation guide here: https://learn.hashicorp.com/tutorials/vault/getting-started-install

Once you've got it installed, you'll need to configure it. HashiCorp has a handy guide for that too: https://www.vaultproject.io/docs/configuration.

Next up, we need to set up a policy in Vault specifically for Supabase. This is basically giving Supabase the right to access certain secrets stored in Vault. HashiCorp has a guide on writing policies: https://www.vaultproject.io/docs/concepts/policies

Your policy might look something like this:

path "secret/data/supabase" {
  capabilities = ["read"]
}

Once you've written that, you can add the policy to Vault using this command:

vault policy write supabase supabase.hcl

Now, we need to generate an API token for Supabase with the policy attached. HashiCorp has a guide on generating tokens: https://www.vaultproject.io/guides/identity/authentication

The command might look like this:

vault token create -policy=supabase

With everything set up, you can now store the necessary Supabase secrets in Vault. This usually includes the Supabase URL and the Service Role Key. You can write the secrets into Vault using this command:

vault kv put secret/supabase url=<SUPABASE_URL> service_role_key=<SERVICE_ROLE_KEY>

Finally, you'll need to configure Supabase to use the Vault token. This is usually done in the .env file. Your configuration might look like this:

For the Supabase URL:

SUPABASE_URL="vault:secret/data/supabase#url"

For the Service Role Key:

SUPABASE_SERVICE_ROLE_KEY="vault:secret/data/supabase#service_role_key"

With this setup, Supabase will use the Vault API token to fetch its secrets from Vault whenever needed, ensuring they're handled and stored safely.