Support Dynamic HTTP Forward Proxy

[guydc]

Description: In some cases, the backend address is not known in advance and must be inferred from request/connection attributes (such as a user-provided host header, jwt claim, TLS SNI, etc.).

The Envoy Dynamic Forward proxy feature can be used to achieve dynamic routing. EG can support Dynamic Forward Proxy in the following manner:

• The EG Backend API can be extended to support a "dynamic" endpoint type, representing a dynamic envoy cluster. This is mostly required for BTLS policy attachment.
• The EG BackendTrafficPolicy can be used to enable dynamic routing:
  • Injecting the appropriate HCM filter
  • Defining the strategy for inferring the upstream address
  • Configuring a DNS cache policy

[optional Relevant Links:]

• https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/http/http_proxy
• https://www.envoyproxy.io/docs/envoy/latest/configuration/listeners/network_filters/sni_dynamic_forward_proxy_filter
• https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/clusters/dynamic_forward_proxy/v3/cluster.proto#envoy-v3-api-msg-extensions-clusters-dynamic-forward-proxy-v3-clusterconfig

[arkodg]

+1