09d0409ed4
This patch is adding configuration option to manipulate with kernel option sysctl_net_ipv4_tcp_retries2. More informations about kernel option in [1][2] and RedHat suggestion [3] to set for DBs and HA. [1]: https://pracucci.com/linux-tcp-rto-min-max-and-tcp-retries2.html [2]: https://blog.cloudflare.com/when-tcp-sockets-refuse-to-die/ [3]: https://access.redhat.com/solutions/726753 Closes-Bug: #1917068 Change-Id: Ia0decbbfa4e33b1889b635f8bb1c9094567a2ce6
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1.4 KiB
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48 lines
1.4 KiB
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.. _haproxy-guide:
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=============
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HAProxy Guide
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=============
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Kolla Ansible supports a Highly Available (HA) deployment of
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Openstack and other services. High-availability in Kolla
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is implented as via Keepalived and HAProxy. Keepalived manages virtual IP
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addresses, while HAProxy load-balances traffic to service backends.
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These two components must be installed on the same hosts
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and they are deployed to hosts in the ``haproxy`` group.
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Preparation and deployment
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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HAProxy and Keepalived are enabled by default. They may be disabled by
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setting the following in ``/etc/kolla/globals.yml``:
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.. code-block:: yaml
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enable_haproxy: "no"
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enable_keepalived: "no"
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Configuration
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~~~~~~~~~~~~~
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Failover tuning
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---------------
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When a VIP fails over from one host to another, hosts may take some
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time to detect that the connection has been dropped. This can lead
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to service downtime.
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To reduce the time by the kernel to close dead connections to VIP
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address, modify the ``net.ipv4.tcp_retries2`` kernel option by setting
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the following in ``/etc/kolla/globals.yml``:
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.. code-block:: yaml
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haproxy_host_ipv4_tcp_retries2: 6
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This is especially helpful for connections to MariaDB. See
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`here <https://pracucci.com/linux-tcp-rto-min-max-and-tcp-retries2.html>`__,
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`here <https://blog.cloudflare.com/when-tcp-sockets-refuse-to-die/>`__ and
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`here <https://access.redhat.com/solutions/726753>`__ for
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further information about this kernel option.
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