Database backed deployments should only be used in a small set of circumstances. We recommend using Gateway Discovery unless you’ve been otherwise advised by a member of the Kong team.
Database backed deployments are when Kong Ingress Controller is used to update a Lua control plane that is attached to a PostgreSQL database. Kong Gateway may be deployed in either Traditional or Hybrid mode.
Both Gateway Discovery and Sidecar deployments can be used alongside a database. If you’re starting a greenfield project today we recommend using Gateway Discovery.
Traditional mode is when every Kong Gateway instance acts as both a control plane and a data plane. All nodes connect to the database and load the latest configuration at a regular interval.
Kong Ingress Controller sends configuration to a random Kong Gateway instance, which writes the configuration to the database. All other nodes read the configuration from the database.
Database backed Hybrid mode is similar to Traditional mode, but instead of every node reading from the database a single control plane is responsible for managing the configuration and distributing it to all active data planes.
In Hybrid mode, Kong Ingress Controller uses Gateway Discovery to find the control plane and send Kong Gateway configuration to the Admin API. This configuration is persisted to the PostgreSQL database and transmitted to the data planes using the Kong Gateway CP/DP protocol.