# gRPC Deadline Propagation
#
# Honours the `grpc-timeout` request header as a real deadline. Without
# this filter the header is forwarded untouched and only the static
# cluster timeouts apply, so a client that asked for 100ms can wait on a
# 30-second upstream read, and every retry restarts the clock.
#
# The filter clamps the client's ask to `max_timeout_ms`, holds it as an
# absolute deadline for the whole request, shrinks each upstream
# attempt's connect and read budget to what is left, and rewrites
# `grpc-timeout` upstream with the remaining time. A call that is
# already past its deadline is answered DEADLINE_EXCEEDED (gRPC status
# 4) without contacting the upstream.
#
# Non-gRPC requests pass through untouched.
#
# Usage:
#   cargo run -p praxis-proxy -- -c examples/configs/traffic-management/grpc-timeout.yaml
#
# Exercise:
#   grpcurl -plaintext -max-time 1 localhost:8080 pkg.Svc/Method

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

filter_chains:
  - name: main
    filters:
      - filter: grpc_timeout
        # Ceiling honoured whatever the client asks for.
        max_timeout_ms: 30000
        # Applied when a call carries no grpc-timeout header. Omit to
        # leave such calls unbounded.
        default_timeout_ms: 10000
        # Kept back from the upstream so the proxy can still answer
        # DEADLINE_EXCEEDED before the client's own timer fires.
        headroom_ms: 50
        # Rewrite grpc-timeout upstream with the remaining budget.
        propagate: true
        # A malformed grpc-timeout is answered INTERNAL (13), as gRPC
        # implementations do. Use `ignore` to fall back to the default.
        on_invalid: reject

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

      - filter: load_balancer
        clusters:
          - name: grpc-backend
            endpoints:
              - "127.0.0.1:50051"
            http:
              version: h2

insecure_options:
  allow_private_endpoints: true # example proxies to a local backend