#############
Haproxy
#############

.. include:: /_include/need_improvement.txt

Haproxy is a balancer and proxy server that provides
high-availability, load balancing and proxying for TCP (level 4)
and HTTP-based (level 7) applications.

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


Service configuration is responsible for binding to a specific port,
while the backend configuration determines the type of load balancing
to be applied and specifies the real servers to be utilized.

Service
-------

.. cfgcmd:: set load-balancing haproxy service <name> listen-address
   <address>

  Set service to bind on IP address, by default listen on any IPv4 and IPv6

.. cfgcmd:: set load-balancing haproxy service <name> port
   <port>

  Create service `<name>` to listen on <port>

.. cfgcmd:: set load-balancing haproxy service <name> mode
   <tcp|http>

  Configure service `<name>` mode TCP or HTTP

.. cfgcmd:: set load-balancing haproxy service <name> backend
   <name>

  Configure service `<name>` to use the backend <name>

.. cfgcmd:: set load-balancing haproxy service <name> ssl
   certificate <name>

  Set SSL certificate <name> for service <name>

.. cfgcmd:: set load-balancing haproxy service <name>
  http-response-headers <header-name> value <header-value>

  Set custom HTTP headers to be included in all responses

.. cfgcmd:: set load-balancing haproxy service <name> logging facility
  <facility> level <level>

  Specify facility and level for logging.
  For an explanation on :ref:`syslog_facilities` and :ref:`syslog_severity_level`
  see tables in syslog configuration section.


Rules
^^^^^
Rules allow to control and route incoming traffic to specific backend based
on predefined conditions. Rules allow to define matching criteria and
perform action accordingly.

.. cfgcmd:: set load-balancing haproxy service <name> rule <rule>
   domain-name <name>

  Match domain name

.. cfgcmd:: set load-balancing haproxy service <name> rule <rule>
   ssl <sni>

  SSL match Server Name Indication (SNI) option:
   * ``req-ssl-sni`` SSL Server Name Indication (SNI) request match
   * ``ssl-fc-sni`` SSL frontend connection Server Name Indication match
   * ``ssl-fc-sni-end`` SSL frontend match end of connection Server Name 
      
      Indication

.. cfgcmd:: set load-balancing haproxy service <name> rule <rule>
   url-path <match> <url>

  Allows to define URL path matching rules for a specific service.

  With this command, you can specify how the URL path should be matched 
  against incoming requests.

  The available options for <match> are:
   * ``begin`` Matches the beginning of the URL path
   * ``end`` Matches the end of the URL path.
   * ``exact`` Requires an exactly match of the URL path

.. cfgcmd:: set load-balancing haproxy service <name> rule <rule>
   set backend <name>

  Assign a specific backend to a rule

.. cfgcmd:: set load-balancing haproxy service <name> rule <rule>
   redirect-location <url>

  Redirect URL to a new location


Backend
-------

.. cfgcmd:: set load-balancing haproxy backend <name> balance
   <balance>

  Load-balancing algorithms to be used for distributed requests among the
  available servers

  Balance algorithms:
   * ``source-address`` Distributes requests based on the source IP address
     of the client
   * ``round-robin`` Distributes requests in a circular manner,
     sequentially sending each request to the next server in line
   * ``least-connection`` Distributes requests to the server with the fewest
     active connections

.. cfgcmd:: set load-balancing haproxy backend <name> mode
   <mode>

  Configure backend `<name>` mode TCP or HTTP

.. cfgcmd:: set load-balancing haproxy backend <name> server
   <name> address <x.x.x.x>

  Set the address of the backend server to which the incoming traffic will
  be forwarded

.. cfgcmd:: set load-balancing haproxy backend <name> server
   <name> port <port>

  Set the address of the backend port

.. cfgcmd:: set load-balancing haproxy backend <name> server
   <name> check

  Active health check backend server

.. cfgcmd:: set load-balancing haproxy backend <name> server
   <name> send-proxy

  Send a Proxy Protocol version 1 header (text format)

.. cfgcmd:: set load-balancing haproxy backend <name> server
   <name> send-proxy-v2

  Send a Proxy Protocol version 2 header (binary format)

.. cfgcmd:: set load-balancing haproxy backend <name> ssl
   ca-certificate <ca-certificate>

  Configure requests to the backend server to use SSL encryption and
  authenticate backend against <ca-certificate>

.. cfgcmd:: set load-balancing haproxy backend <name> ssl no-verify

  Configure requests to the backend server to use SSL encryption without
  validating server certificate

.. cfgcmd:: set load-balancing haproxy backend <name>
  http-response-headers <header-name> value <header-value>

  Set custom HTTP headers to be included in all responses using the backend

.. cfgcmd:: set load-balancing haproxy backend <name> logging facility
  <facility> level <level>

  Specify facility and level for logging.
  For an explanation on :ref:`syslog_facilities` and :ref:`syslog_severity_level`
  see tables in syslog configuration section.


Global
-------

Global parameters

.. cfgcmd:: set load-balancing haproxy global-parameters max-connections
   <num>

  Limit maximum number of connections

.. cfgcmd:: set load-balancing haproxy global-parameters ssl-bind-ciphers
   <ciphers>

  Limit allowed cipher algorithms used during SSL/TLS handshake

.. cfgcmd:: set load-balancing haproxy global-parameters tls-version-min
   <version>

  Specify the minimum required TLS version 1.2 or 1.3

.. cfgcmd:: set load-balancing haproxy global-parameters logging
  facility <facility> level <level>

  Specify facility and level for logging.
  For an explanation on :ref:`syslog_facilities` and :ref:`syslog_severity_level`
  see tables in syslog configuration section.

Health checks
=============


HTTP checks
-----------

For web application providing information about their state HTTP health
checks can be used to determine their availability.

.. cfgcmd:: set load-balancing haproxy backend <name> http-check

  Enables HTTP health checks using OPTION HTTP requests against '/' and
  expecting a successful response code in the 200-399 range.

.. cfgcmd:: set load-balancing haproxy backend <name> http-check
   method <method>

  Sets the HTTP method to be used, can be either: option, get, post, put

.. cfgcmd:: set load-balancing haproxy backend <name> http-check
   uri <path>

  Sets the endpoint to be used for health checks

.. cfgcmd:: set load-balancing haproxy backend <name> http-check
   expect <condition>

  Sets the expected result condition for considering a server healthy.

  Some possible examples are:
   * ``status 200`` Expecting a 200 response code
   * ``status 200-399`` Expecting a non-failure response code
   * ``string success`` Expecting the string `success` in the response body


TCP checks
----------

Health checks can also be configured for TCP mode backends. You can configure
protocol aware checks for a range of Layer 7 protocols:

.. cfgcmd:: set load-balancing haproxy backend <name> health-check <protocol>

  Available health check protocols:
   * ``ldap`` LDAP protocol check.
   * ``redis`` Redis protocol check.
   * ``mysql`` MySQL protocol check.
   * ``pgsql`` PostgreSQL protocol check.
   * ``smtp`` SMTP protocol check.

.. note:: If you specify a server to be checked but do not configure a
   protocol, a basic TCP health check will be attempted. A server shall be
   deemed online if it responses to a connection attempt with a valid
   ``SYN/ACK`` packet.


Redirect HTTP to HTTPS
======================
Configure the load-balancing haproxy service for HTTP.

This configuration listen on port 80 and redirect incoming
requests to HTTPS:

.. code-block:: none

    set load-balancing haproxy service http port '80'
    set load-balancing haproxy service http redirect-http-to-https

The name of the service can be different, in this example it is only for 
convenience.


Examples
========

Level 4 balancing
-----------------

This configuration enables the TCP reverse proxy for the "my-tcp-api" service.
Incoming TCP connections on port 8888 will be load balanced across the backend
servers (srv01 and srv02) using the round-robin load-balancing algorithm.

.. code-block:: none

    set load-balancing haproxy service my-tcp-api backend 'bk-01'
    set load-balancing haproxy service my-tcp-api mode 'tcp'
    set load-balancing haproxy service my-tcp-api port '8888'

    set load-balancing haproxy backend bk-01 balance 'round-robin'
    set load-balancing haproxy backend bk-01 mode 'tcp'

    set load-balancing haproxy backend bk-01 server srv01 address '192.0.2.11'
    set load-balancing haproxy backend bk-01 server srv01 port '8881'
    set load-balancing haproxy backend bk-01 server srv02 address '192.0.2.12'
    set load-balancing haproxy backend bk-01 server srv02 port '8882'


Balancing based on domain name
------------------------------
The following configuration demonstrates how to use VyOS
to achieve load balancing based on the domain name.

The HTTP service listen on TCP port 80.

Rule 10 matches requests with the domain name ``node1.example.com`` forwards
to the backend ``bk-api-01``

Rule 20 matches requests with the domain name ``node2.example.com`` forwards
to the backend ``bk-api-02``

.. code-block:: none

    set load-balancing haproxy service http description 'bind app listen on 443 port'
    set load-balancing haproxy service http mode 'tcp'
    set load-balancing haproxy service http port '80'

    set load-balancing haproxy service http rule 10 domain-name 'node1.example.com'
    set load-balancing haproxy service http rule 10 set backend 'bk-api-01'
    set load-balancing haproxy service http rule 20 domain-name 'node2.example.com'
    set load-balancing haproxy service http rule 20 set backend 'bk-api-02'

    set load-balancing haproxy backend bk-api-01 description 'My API-1'
    set load-balancing haproxy backend bk-api-01 mode 'tcp'
    set load-balancing haproxy backend bk-api-01 server api01 address '127.0.0.1'
    set load-balancing haproxy backend bk-api-01 server api01 port '4431'
    set load-balancing haproxy backend bk-api-02 description 'My API-2'
    set load-balancing haproxy backend bk-api-02 mode 'tcp'
    set load-balancing haproxy backend bk-api-02 server api01 address '127.0.0.2'
    set load-balancing haproxy backend bk-api-02 server api01 port '4432'


Terminate SSL
-------------
The following configuration terminates SSL on the router.

The ``http`` service is listens on port 80 and force redirects from HTTP to
HTTPS.

The ``https`` service listens on port 443 with backend ``bk-default`` to
handle HTTPS traffic. It uses certificate named ``cert`` for SSL termination.
HSTS header is set with a 1-year expiry, to tell browsers to always use SSL for site.

Rule 10 matches requests with the exact URL path ``/.well-known/xxx``
and redirects to location ``/certs/``.

Rule 20 matches requests with URL paths ending in ``/mail`` or exact
path ``/email/bar`` redirect to location ``/postfix/``.

Additional global parameters are set, including the maximum number
connection limit of 4000 and a minimum TLS version of 1.3.


.. code-block:: none

    set load-balancing haproxy service http description 'Force redirect to HTTPS'
    set load-balancing haproxy service http port '80'
    set load-balancing haproxy service http redirect-http-to-https

    set load-balancing haproxy service https backend 'bk-default'
    set load-balancing haproxy service https description 'listen on 443 port'
    set load-balancing haproxy service https mode 'http'
    set load-balancing haproxy service https port '443'
    set load-balancing haproxy service https ssl certificate 'cert'
    set load-balancing haproxy service https http-response-headers Strict-Transport-Security value 'max-age=31536000'

    set load-balancing haproxy service https rule 10 url-path exact '/.well-known/xxx'
    set load-balancing haproxy service https rule 10 set redirect-location '/certs/'
    set load-balancing haproxy service https rule 20 url-path end '/mail'
    set load-balancing haproxy service https rule 20 url-path exact '/email/bar'
    set load-balancing haproxy service https rule 20 set redirect-location '/postfix/'

    set load-balancing haproxy backend bk-default description 'Default backend'
    set load-balancing haproxy backend bk-default mode 'http'
    set load-balancing haproxy backend bk-default server sr01 address '192.0.2.23'
    set load-balancing haproxy backend bk-default server sr01 port '80'

    set load-balancing haproxy global-parameters max-connections '4000'
    set load-balancing haproxy global-parameters tls-version-min '1.3'


SSL Bridging
-------------
The following configuration terminates incoming HTTPS traffic on the router,
then re-encrypts the traffic and sends to the backend server via HTTPS.
This is useful if encryption is required for both legs, but you do not want to
install publicly trusted certificates on each backend server.

Backend service certificates are checked against the certificate authority
specified in the configuration, which could be an internal CA.

The ``https`` service listens on port 443 with backend ``bk-bridge-ssl`` to
handle HTTPS traffic. It uses certificate named ``cert`` for SSL termination.

The ``bk-bridge-ssl`` backend connects to sr01 server on port 443 via HTTPS
and checks backend server has a valid certificate trusted by CA ``cacert``


.. code-block:: none

    set load-balancing haproxy service https backend 'bk-bridge-ssl'
    set load-balancing haproxy service https description 'listen on 443 port'
    set load-balancing haproxy service https mode 'http'
    set load-balancing haproxy service https port '443'
    set load-balancing haproxy service https ssl certificate 'cert'

    set load-balancing haproxy backend bk-bridge-ssl description 'SSL backend'
    set load-balancing haproxy backend bk-bridge-ssl mode 'http'
    set load-balancing haproxy backend bk-bridge-ssl ssl ca-certificate 'cacert'
    set load-balancing haproxy backend bk-bridge-ssl server sr01 address '192.0.2.23'
    set load-balancing haproxy backend bk-bridge-ssl server sr01 port '443'


Balancing with HTTP health checks
---------------------------------

This configuration enables HTTP health checks on backend servers.

.. code-block:: none

    set load-balancing haproxy service my-tcp-api backend 'bk-01'
    set load-balancing haproxy service my-tcp-api mode 'tcp'
    set load-balancing haproxy service my-tcp-api port '8888'

    set load-balancing haproxy backend bk-01 balance 'round-robin'
    set load-balancing haproxy backend bk-01 mode 'tcp'

    set load-balancing haproxy backend bk-01 http-check method 'get'
    set load-balancing haproxy backend bk-01 http-check uri '/health'
    set load-balancing haproxy backend bk-01 http-check expect 'status 200'

    set load-balancing haproxy backend bk-01 server srv01 address '192.0.2.11'
    set load-balancing haproxy backend bk-01 server srv01 port '8881'
    set load-balancing haproxy backend bk-01 server srv01 check
    set load-balancing haproxy backend bk-01 server srv02 address '192.0.2.12'
    set load-balancing haproxy backend bk-01 server srv02 port '8882'
    set load-balancing haproxy backend bk-01 server srv02 check