Add support for addon-specific environment variables and secrets management

[tiborrr]

Add Environment Variables Support for Addons

Problem

Docspell addons need a secure and standardized way to handle environment variables and secrets. Currently, there's no built-in way to pass environment variables to addons.

Proposed Solution

docspell.joex.addons {
  configs = [
    {
      name = "my-postgres-addon"
      enabled = true
      envs = [
        {
          name = "POSTGRES_HOST"
          value = "localhost"
        },
        {
          name = "POSTGRES_PASSWORD"
          valueFrom = { # future feature
            env = "DS_POSTGRES_PASSWORD" 
          }
        }
      ]
    }
  ]
}

Environment Variable Mapping

DOCSPELL_JOEX_ADDONS_CONFIGS_0_NAME="my-postgres-addon"
DOCSPELL_JOEX_ADDONS_CONFIGS_0_ENVS_0_NAME="POSTGRES_HOST"
DOCSPELL_JOEX_ADDONS_CONFIGS_0_ENVS_0_VALUE="localhost"
DOCSPELL_JOEX_ADDONS_CONFIGS_0_ENVS_1_NAME="POSTGRES_PASSWORD"

Key Features

• Simple array-based configuration
• Support for direct values and environment variable references
• Extensible valueFrom field for future secret providers
• Consistent with Docspell's configuration style

Future Extensions

The valueFrom field can be extended to support additional providers like:

• File-based secrets
• HashiCorp Vault
• Kubernetes secrets
• Cloud provider secret managers