How setup Haproxy with zero downtime reload from code source

Juan Enciso
IT Architect, SRE Engineer, DevOps Tools Trainer
Oct 1, 2018 3 min read

if you are looking for a modern load balancer with zero downtime when you need to reload its configuration, HAProxy 1.8 and Linux kernel >=3.9 could take advantage of a new reload mechanism which can transfer sockets from the old process to the new process without dropping any connections.

On on-premise scenario, this enable the dynamic scalability and continuous integration into your production datacenter.

Follow the next steps to install a new version of haproxy, in this case the release 1.8.14, it include the reload daemon when the config file (haproxy.cfg) need to be changed.

Steps

Download the compatible haproxy version

export HAPROXY_MAJOR=1.8
export HAPROXY_VERSION=1.8.14
export HAPROXY_URL=https://www.haproxy.org

wget -O haproxy.tar.gz \
 "$HAPROXY_URL=/download/${HAPROXY_MAJOR}/src/haproxy-${HAPROXY_VERSION}.tar.gz"

Installing the prerequisites packages to compile

For ubuntu 16.04:

sudo apt-get update && sudo apt-get install -y ca-certificates gcc \
  libc6-dev liblua5.3-dev libpcre3-dev libssl-dev make wget \
  zlib1g-dev libsystemd-dev

For Centos 7.5:

yum install -y inotify-tools wget tar gzip make gcc perl pcre-devel zlib-devel iptables \
  openssl openssl-devel openssl-libs systemd-devel

Compiling

tar xvfz haproxy.tar.gz
cd haproxy-1.8.14/

For ubuntu:

make TARGET=linux2628 USE_GETADDRINFO=1 USE_ZLIB=1 USE_REGPARM=1 USE_OPENSSL=1 \
  USE_LUA=1 USE_SYSTEMD=1 USE_PCRE=1 USE_PCRE_JIT=1 USE_NS=1
make install

For Centos 7.5:

make TARGET=linux2628 USE_GETADDRINFO=1 USE_ZLIB=1 USE_REGPARM=1 USE_OPENSSL=1 \
  USE_SYSTEMD=1 USE_PCRE=1 USE_PCRE_JIT=1 USE_NS=1
make install

During the compilation process, you could verify the compile options passed via make, so you have to get the USE_SYSTEMD=1 via the stdout log, like this:

HA-Proxy version 1.8.14-52e4d43 2018/09/20
Copyright 2000-2018 Willy Tarreau <willy@haproxy.org>

Build options :
  TARGET  = linux2628
  CPU     = generic
  CC      = gcc
  CFLAGS  = -O2 -g -fno-strict-aliasing -Wdeclaration-after-statement -fwrapv -fno-strict-overflow -Wno-unused-label
  OPTIONS = USE_GETADDRINFO=1 USE_ZLIB=1 USE_REGPARM=1 USE_OPENSSL=1 USE_LUA=1 USE_SYSTEMD=1 USE_PCRE=1 USE_PCRE_JIT=1 USE_NS=1

Default settings :
  maxconn = 2000, bufsize = 16384, maxrewrite = 1024, maxpollevents = 200

Built with OpenSSL version : OpenSSL 1.0.2g  1 Mar 2016
Running on OpenSSL version : OpenSSL 1.0.2g  1 Mar 2016
OpenSSL library supports TLS extensions : yes
OpenSSL library supports SNI : yes
OpenSSL library supports : TLSv1.0 TLSv1.1 TLSv1.2
Built with Lua version : Lua 5.3.1
Built with transparent proxy support using: IP_TRANSPARENT IPV6_TRANSPARENT IP_FREEBIND
Encrypted password support via crypt(3): yes
Built with multi-threading support.
Built with PCRE version : 8.38 2015-11-23
Running on PCRE version : 8.38 2015-11-23
PCRE library supports JIT : yes
Built with zlib version : 1.2.8
Running on zlib version : 1.2.8
Compression algorithms supported : identity("identity"), deflate("deflate"), raw-deflate("deflate"), gzip("gzip")
Built with network namespace support.

Available polling systems :
      epoll : pref=300,  test result OK
       poll : pref=200,  test result OK
     select : pref=150,  test result OK
Total: 3 (3 usable), will use epoll.

Available filters :
	[SPOE] spoe
	[COMP] compression
	[TRACE] trace