Plugin API Key Configuration#

Dify's plugin system uses two distinct shared-secret keys for inter-service authentication between the api/worker/agent_backend services and the plugin_daemon:

The two keys#

PLUGIN_DAEMON_KEY — authenticates calls from the api and worker services to the plugin daemon.

• Python default: "plugin-api-key" 1
• api/.env.example ships the value lYkiYYT6owG+71oLerGzA7GXCgOT++6ovaezWAjpCjf+Sjc3ZtU+qUEi 2
• docker/.env.example sets the same literal as default for the Docker deployment 3
• The compose file passes it to plugin_daemon as SERVER_KEY

INNER_API_KEY_FOR_PLUGIN — authenticates callbacks from plugin_daemon and agent_backend into the api. This is the "inner API key" that the API server validates on incoming requests.

• Python default: "inner-api-key" 4
• api/.env.example ships the value QaHbTe77CtuXmsfyhR7+vRjI/+XbV1AaFy691iy+kGDv2Jvy0/eAh8Y1 5
• docker/.env.example defines it as PLUGIN_DIFY_INNER_API_KEY (daemon's variable name) with the same value 6
• The compose file injects it into both api/worker as INNER_API_KEY_FOR_PLUGIN and into plugin_daemon as DIFY_INNER_API_KEY — both sourced from ${PLUGIN_DIFY_INNER_API_KEY} 7 8

Synchronization in docker-compose.yaml#

The single PLUGIN_DIFY_INNER_API_KEY variable in docker/.env is the synchronization point. Compose maps it to the correct environment variable name for each service:

• api service: INNER_API_KEY_FOR_PLUGIN: ${PLUGIN_DIFY_INNER_API_KEY:-QaHbTe77...} 7
• worker service: INNER_API_KEY_FOR_PLUGIN: ${PLUGIN_DIFY_INNER_API_KEY:-QaHbTe77...} 9
• plugin_daemon service: DIFY_INNER_API_KEY: ${PLUGIN_DIFY_INNER_API_KEY:-QaHbTe77...} 8
• agent_backend service: DIFY_AGENT_INNER_API_KEY: ${DIFY_AGENT_INNER_API_KEY:-${PLUGIN_DIFY_INNER_API_KEY:-QaHbTe77...}} 10

Similarly, PLUGIN_DAEMON_KEY from docker/.env feeds both api/worker (via shared-api-worker-config env_file) and plugin_daemon (SERVER_KEY) and agent_backend (DIFY_AGENT_PLUGIN_DAEMON_API_KEY) 11.

Enforcement in the API#

The plugin_inner_api_only decorator in api/controllers/inner_api/wraps.py enforces this key:

1. Returns 404 if PLUGIN_DAEMON_KEY is not set (guards the entire inner API surface).
2. Reads the X-Inner-Api-Key request header.
3. Returns 404 if the header doesn't match INNER_API_KEY_FOR_PLUGIN.

The agent_inner_api_only decorator 12 is an alias for plugin_inner_api_only — the agent_backend shares the same credentials for its callbacks into the API.

Production security#

The hardcoded fallback values in compose (lYkiYYT6owG+... / QaHbTe77...) are insecure defaults. PR #34408 introduced CI tooling to detect and replace blank secrets, but the compose fallbacks still exist. For production:

• Set PLUGIN_DAEMON_KEY and PLUGIN_DIFY_INNER_API_KEY to independent random strings (e.g., openssl rand -base64 42) in docker/.env.
• Both must be set to the same values at the same time across all affected services; a mismatch will cause 404 responses on all plugin-initiated callbacks and inner API tool calls.
• AGENT_BACKEND_API_TOKEN / DIFY_AGENT_API_TOKEN (the token the api uses to call agent_backend) is a separate secret and must also be rotated 13 14.

Quick reference — variable names per service#