Kernel needs
==============

  Compile a kernel with the following options :

  Kernel/User netlink socket
  LinuxVirtualServer

  Keepalived supports all LVS code.

Library dependencies
====================

  In order to compile Keepalived needs the following libraries :

  * OpenSSL, <www.openssl.org>

Linux flavours
==============

RedHat based systems (RedHat Enterprise/CentOS/Fedora)
------------------------------------------------------
The following build packages are needed:
	make
	autoconf automake (to build from git source tree rather than tarball)
The following libraries need to be installed:
	openssl-devel libnl3-devel
For iptables support:
	iptables-devel ipset-devel
For magic file identification support:
	file-devel
For SNMP support:
	net-snmp-devel
For DBUS support:
	glib2-devel
For PCRE support
	pcre2-devel
For nftables support
	libnftnl-devel libmnl-devel
For systemd integration
	systemd-devel

For building the documentation, the following packages need to be installed:
	Fedora: python-sphinx (will pull in: python2-sphinx_rtd_theme)
	CentOS-and-friends: python-sphinx epel-release python-sphinx_rtd_theme
   For latex or pdf files, the following are also needed:
	Fedora: latexmk python-sphinx-latex
	CentOS-and-friends: latexmk texlive texlive-titlesec texlive-framed texlive-threeparttable texlive-wrapfig texlive-multirow

To build using clang/llvm
	clang compiler-rt lld

Debian/Ubuntu
-------------
For building packages:
	build-essential pkg-config, and to build from git repo automake autoconf
The following libraries need to be installed:
	iptables-dev libipset-dev libnl-3-dev libnl-genl-3-dev libssl-dev
  or for more recent versions of the distros (e.g. Ubuntu Focal):
	libxtables-dev libip4tc-dev libip6tc-dev libipset-dev libnl-3-dev libnl-genl-3-dev libssl-dev
For magic file identification support:
	libmagic-dev
For SNMP support:
	libsnmp-dev
For DBUS support:
	libglib2.0-dev
For PCRE support:
	libpcre2-dev
For nftables support
	libnftnl-dev libmnl-dev
For systemd integration
	libsystemd-dev

For building the documentation, the following packages need to be installed:
	python-sphinx python-sphinx-rtd-theme
   For latex or pdf files, the following are also needed:
	texlive-latex-base texlive-generic-extra texlive-latex-recommended texlive-fonts-recommended texlive-latex-extra

Alpine Linux
------------
The following libraries need to be installed:
	iptables-dev ipset-dev libnl3-dev musl-dev libnftnl-dev and openssl-dev or libressl-dev
For magic file identification support:
	file-dev
For SNMP support:
	net-snmp-dev (requires libressl-dev and not openssl-dev)
For PCRE support
	pcre2-dev

For building the documentation, the following packages need to be installed:
	py-sphinx py3-sphinx_rtd_theme
   For latex or pdf files, you'll need texlive or similar, which is not yet
   available as a distro package.


Archlinux
---------
Run the following to install the required libraries:
	pacman -S ipset libnl1
For magic file identification support:
	TDB
For SNMP support:
	pacman -S net-snmp
for PCRE support:
	pcre-2 (may be installed by default)

For building the documentation, the following packages need to be installed:
	python-sphinx python-sphinx_rtd_theme
   For latex or pdf files, the following are also needed:
	texlive-core texlive-bin texlive-latexextra

Kernel configuration requirements
---------------------------------
The following list is probably incomplete, and will be updated as other
options become known.

BPF
EPOLL
SIGNALFD
TIMERFD
SYSCTL
PROC_FS
INET
IP_MULTICAST
IPV6
IP_VS (unless --disable-lvs is specified)
  IP_VS suboptions to match the real_server/virtual_server configuration
NETFILTER_XTABLES - if strict_mode or no_accept.
  NETFILTER_XT options and IP_SET
NF_TABLES and associated components - to use nftables for strict_mode or no_accept
IP_ADVANCED_ROUTER and various associated options if static/dynamic routes specified
FIB_RULES if static or dynamic rules are specified

Installing from a git repo
==========================
To install from a git repo, execute:
  1. Ensure you have autoconf and automake installed
  2. git clone https://github.com/acassen/keepalived.git
  3. cd keepalived
  4. ./build_setup	# generate the autoconf and automake environment
  5. Follow the instructions below for Installation, omitting the first two steps.

Installation
============

  1. tar -xf TARFILE
  2. cd into the directory
  3. './configure'
  4. 'make'
  5. 'make install'. This will install keepalived on your system,
     binaries and configuration file :
     * keepalived : The keepalived daemon program.
     * genhash    : The MD5 url digest generator. You need it to
                    configure HTTP GET check and SSL GET check in
                    order to compute MD5SUM digest etalon.
     * /etc/keepalived/keepalived.conf
  6. link keepalived.init into your runlevel directory. On Red Hat systems :
     ln -s /etc/rc.d/init.d/keepalived.init /etc/rc.d/rc3.d/S99keepalived

  By default the configure script uses /usr/local as base directory. You can
  change this value to your own by passing it the --prefix value.

  eg: './configure --prefix=/usr/'

Building RPM files
==================

 If building from tarball:
  1a. tar -xf TARFILE
  1b. cd into the directory

 If building from git clone:
  1. ./build_setup 

 For tarball and git
  2. ./configure
  3. make rpm

 The .rpm files will be created in directory `rpm --eval "%{_rpmdir}"`/ARCH

Modifying source code
=====================

If you modify the source code, especially configure.ac or any Makefile.am
file, you will need to regenerate the build files. Keepalived uses automake
and so you will need to have automake and autoconf installed.

Configuration
=============

  Just take a look at the /etc/keepalived/keepalived.conf file installed.
  It will give you all the information needed. Alternativley, run
  'man keepalived.conf' or look at doc/keepalived.conf.SYNOPSIS.
  If you want more information about keepalived, please refer to the
  keepalived homepage into the documentation section.

  http://www.keepalived.org


Creating a docker container
===========================
There is a very useful github project maintained by osixia for building a
docker container with keepalived.

To use, run the following:
git clone https://github.com/osixia/docker-keepalived.git
cd docker-keepalived
make build
docker run --name keepalived --cap-add=NET_ADMIN --net=host \
  --env KEEPALIVED_INTERFACE=eth0 -d osixia/keepalived:1.3.5 \
	# or whatever version of keepalived you have

To update the keepalived source code, put a new tarball in the image
directory (the Dockerfile may need updating with a new version).

Useful docker commands are:
docker logs keepalived 2>&1 | less	# view system logs of container
docker exec -it keepalived bash		# execute shell in container
docker rm -f keepalived			# Remove the container

keepalived is unable to load the ip_tables, ip6_tables, xt_set and ip_vs
modules from within the container, so ensure they are already loaded in
the host system.

To generate a core file in the root filesystem of the container,
/proc/sys/kernel/core_pattern needs to be updated in the host system,
and not from the container (or in other words the -M option to keepalived
does not work within a container. Installing gdb in the container (edit
the image/Dockerfile to add it before make build) may be helpful if you
need to examine core files in the container.


Running in an AWS container
===========================
The VRRP protocol is not enabled in AWS security groups. If you are using AWS,
create a rule in the AWS security group. The rule should be "Custom Protocol"
and value should be "112" (the VRRP protocol number). All ports should be opened.


Running with SELinux
====================
If the system running keepalived has SELinux enabled in enforcing mode, keepalived
may have difficulty running scripts, accessing configuration files, etc, especially
if keepalived is being started by systemd.

By default, scripts should be located in /usr/libexec/keepalived, or alternatively,
to set the necessary security context for a script, execute:
chcon -t keepalived_unconfined_script_exec_t PATH_TO_SCRIPT

See
   https://www.mankier.com/8/keepalived_selinux and
   https://www.mankier.com/8/keepalived_unconfined_script_selinux
for further details of SElinux and keepalived.


Have fun with it !

Alexandre, <acassen@linux-vs.org>
