# gRPC Upstream over HTTP/2
#
# Praxis proxies to upstreams over HTTP/1.1 by default. gRPC backends
# speak HTTP/2 only, and a call's outcome (`grpc-status`) arrives in
# response trailers, which no HTTP/1.1 leg can carry. Set a cluster's
# `http.version` to `h2` to give it an HTTP/2 upstream connection.
#
# Values:
#   h1    HTTP/1.1 only (default; Praxis's historical behaviour)
#   h2    HTTP/2 only — ALPN `h2` over TLS, prior-knowledge h2c over plaintext
#   auto  prefer HTTP/2, fall back to HTTP/1.1 (TLS only; plaintext has
#         no negotiation mechanism, so `auto` connects over HTTP/1.1)
#
# Usage:
#   cargo run -p praxis-proxy -- -c examples/configs/protocols/grpc-http2-upstream.yaml
#
# Exercise (with any gRPC client, e.g. grpcurl):
#   grpcurl -plaintext localhost:8080 pkg.Svc/Method

listeners:
  - name: grpc
    address: "127.0.0.1:8080"
    protocol: http
    filter_chains: [main]

filter_chains:
  - name: main
    filters:
      # Gate gRPC-specific handling on the traffic itself.
      - filter: grpc_detection
        conditions:
          - when:
              grpc: true

      - filter: router
        routes:
          - path_prefix: "/"
            cluster: grpc-backend

      - filter: load_balancer
        clusters:
          - name: grpc-backend
            endpoints:
              - "127.0.0.1:50051"
            http:
              # Required for gRPC: trailers only exist on an HTTP/2 leg.
              version: h2

insecure_options:
  allow_private_endpoints: true # example proxies to local backends