Backend connection
- backend.conn.is_tls
- backend.conn.tls_protocol
- backend.socket.congestion_algorithm
- backend.socket.cwnd
- backend.socket.tcpi_advmss
- backend.socket.tcpi_bytes_acked
- backend.socket.tcpi_bytes_received
- backend.socket.tcpi_data_segs_in
- backend.socket.tcpi_data_segs_out
- backend.socket.tcpi_delivery_rate
- backend.socket.tcpi_delta_retrans
- backend.socket.tcpi_last_data_sent
- backend.socket.tcpi_max_pacing_rate
- backend.socket.tcpi_min_rtt
- backend.socket.tcpi_notsent_bytes
- backend.socket.tcpi_pacing_rate
- backend.socket.tcpi_pmtu
- backend.socket.tcpi_rcv_mss
- backend.socket.tcpi_rcv_rtt
- backend.socket.tcpi_rcv_space
- backend.socket.tcpi_rcv_ssthresh
- backend.socket.tcpi_reordering
- backend.socket.tcpi_rtt
- backend.socket.tcpi_rttvar
- backend.socket.tcpi_segs_in
- backend.socket.tcpi_segs_out
- backend.socket.tcpi_snd_cwnd
- backend.socket.tcpi_snd_mss
- backend.socket.tcpi_snd_ssthresh
- backend.socket.tcpi_total_retrans
- backend.{NAME}.connections_open
- backend.{NAME}.connections_used
- backend.{NAME}.healthy
- bereq.between_bytes_timeout
- bereq.connect_timeout
- bereq.first_byte_timeout
- beresp.backend.alternate_ips
- beresp.backend.ip
- beresp.backend.port
- beresp.backend.requests
- beresp.backend.src_ip
- beresp.handshake_time_to_origin_ms
- beresp.used_alternate_path_to_origin
- req.backend
- req.backend.healthy
- req.backend.is_origin
- req.backend.is_shield
