HAProxy Docker Setup

When doing local development/testing, I find myself constantly referring to online examples on setting up a local HAProxy, for various HTTP Request manipulations. Instead of feeding Google the same searches ever other week, I finally decided to create a post in order to reference it myself, but also hoping that it will reinforce my understanding of it so that I don’t need to look it up everytime.

I’ll be using Docker in this example, but Podman is definitely on the radar for next time. Since most of us have probably already used Docker already, this should be a really quick post.

Steps

First, pull the image. I prefer to use the Alpine image since it’s small, and quick to pull, but use whatever you need to use. See HAProxy’s Docker Hub page for a list of all versions.

docker pull haproxy:1.8-alpine

Now run it.

docker run --rm docker.io/haproxy:1.8-alpine

But not so fast. You’ll get an error message that says the following.

[ALERT] 028/063713 (1) : Cannot open configuration file/directory /usr/local/etc/haproxy/haproxy.cfg : No such file or directory

The README didn’t say that it required it, but I guess you should assume it needs some sort of configuration.

So let’s try this.

docker run -v /tmp/haproxy.config:/usr/local/etc/haproxy/haproxy.cfg --rm docker.io/haproxy:1.8-alpine

But I was getting this error message now.

[ALERT] 028/064711 (1) : Could not open configuration file /usr/local/etc/haproxy/haproxy.cfg : Permission denied

The solution is to add the :Z modifier to the volume mount. After reading the documentation, the Z flag is something to do with SELinux, but that’s all I really care to know when running my simple, test containers locally. This would be a different story if real work was being done on a production server somewhere.

The final solution is this.

docker run -v /tmp/haproxy.config:/usr/local/etc/haproxy/haproxy.cfg:Z --rm docker.io/haproxy:1.8-alpine

Sample HAProxy Configuration

Here’s a sample HAProxy config file too. It does some weird things that’s only useful for myself, so your config will be completely different.

global
  debug                       # uncomment to enable debug mode for HAProxy

defaults
  mode                    http
  option                  httplog
  option                  dontlognull
  option http-server-close
  option forwardfor       except 127.0.0.0/8
  option                  redispatch
  retries                 3
  timeout http-request    10s
  timeout queue           1m
  timeout http-keep-alive 10s
  timeout check           10s
  maxconn                 3000

  timeout connect 5000ms       # max time to wait for a connection attempt to a server to succeed
  timeout client 50000ms       # max inactivity time on the client side
  timeout server 50000ms       # max inactivity time on the server side
###############

frontend http-apps             # define what port to listed to for HAProxy
  mode tcp#http
  bind *:980
  default_backend legacy-http

backend legacy-http            # define a group of backend servers to handle legacy requests
  mode tcp#http
  server spring-boot-8080 192.168.122.224:80 send-proxy  # add a server to this backend
  reqidel ^X-Forwarded-For:.*

###############

frontend https-apps            # define what port to listed to for HAProxy
  mode tcp
  bind *:9443
  default_backend legacy-https

backend legacy-https           # define a group of backend servers to handle legacy requests
  mode tcp
  server spring-boot-8443 192.168.122.224:443 send-proxy  # add a server to this backend
##############