HAProxy improvements

date:2015-09-04 14:00
tags:haproxy, production use

HA Proxy can be improved by adding a few changes:

  • Making it really HA
  • Allowing configuration interface to easily adapt load
  • Deploying only the configuration for the services deployed within the inventory.
  • Improving backends configuration, for example galera or adapting the timer values to be more efficient

https://blueprints.launchpad.net/openstack-ansible/+spec/role-haproxy-v2

Problem description

There are a few features already asked by the community:

  • HA for haproxy
  • Enable statistics and improve manageability of haproxy
  • Limiting the unnecessary checks of haproxy

Proposed change

  • Implement keepalived for haproxy
  • Change the standard haproxy role to add administrative tools (admin level on socket and stats)
  • Remove the large haproxy variable in vars/ folder
  • Give this information component by component (in the group_vars), and make it possible to have user overrides (user_variables or component by component). Then delegate the configuration to haproxy hosts.
  • Introduce a skip variable, if you want to deploy haproxy on some components but not some others

Alternatives

Wait for ansible2 to have variable merging/cleanup for dicts on a per task/playbook basis.

Playbook/Role impact

The playbook haproxy-install.yml will be completely overwritten.

haproxy playbook run will be longer, due to the delegate to.

Upgrade impact

None.

Security impact

No change

Performance impact

Improved performance by:

  • Doing less unnecessary checks to backends
  • Adding an easy way to set customer values for the backend’s timers.

End user impact

No change

Deployer impact

  • No change in default configuration
  • The deployer can overwrite the haproxy_service_configs per component

Developer impact

No impact at first sight.

Dependencies

None

Implementation

Assignee(s)

None

Work items

Testing

  • Does this change impact how gating is done?

There will be a change to haproxy-install playbook if merged.

  • Can this change be tested on a per-commit basis?

Yes

  • Given the instance size restrictions, as found in OpenStack Infra (8GB Ram, vCPUs <= 8), can the test be run in a resource constrained environment?

No change

  • Is this untestable given current limitations (specific hardware / software configurations available)? If so, are there mitigation plans for this change to be tested within 3rd party testing, gate enhancements, etc...?

No

  • If the service is not OpenStack specific how can we test the change?

Running the new playbooks

Documentation impact

For those who change the default configuration of haproxy (currently not documented), this change would modify their current configuration, so it needs to be documented. Explanation of the skip variable and component by component override should be good to add in the doc too.

References

None