haproxy strip path prefix

README.md

docker-compose build --no-cache haproxy && docker-compose up -d
$ curl 0.0.0.0:8080/echob/metrics
hello from service b
$ curl 0.0.0.0:8080/echoa/metrics
hello from service a

docker-compose.yaml

version: "3.3"
services:
  service-a:
    image: hashicorp/http-echo
    command: -text="hello from service a"

  service-b:
    image: hashicorp/http-echo
    command: -text="hello from service b"

  haproxy:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "8080:8080"
    depends_on:
      - service-a
      - service-b

Dockerfile

FROM haproxy:1.7
COPY haproxy.cfg /usr/local/etc/haproxy/haproxy.cfg

haproxy.cfg

defaults
  log               global
  retries           3
  maxconn           2000
  timeout connect   5s
  timeout client    50s
  timeout server    50s

frontend services-echo
  mode http
  bind :8080

  acl echoa_path path_beg /echoa
  acl echob_path path_beg /echob

  use_backend echoa if echoa_path
  use_backend echob if echob_path

backend echoa
  mode http
  reqrep ^([^\ ]*\ /)echoa[/]?(.*)     \1\2
  server service-a service-a:5678

backend echob
  mode http
  reqrep ^([^\ ]*\ /)echob[/]?(.*)     \1\2
  server service-b service-b:5678