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We have a high-availability setup in which distributes requests between a set of backend servers ('realservers' in LVS-speak). LVS is managed by . Each realserver exposes a health check resource over HTTP (basically, if you say GET /info/health to one of them, it will respond with either healthy or ill), and keepalived is configured to poll these resources every 15 seconds to check realserver health. If a realserver becomes unhealthy, keepalived zeroes its weight in the virtual server table, so no traffic is sent to it. All fairly normal stuff, i believe.

Sometimes, it would be really useful to tell keepalived to make a health check for a specific realserver (or all the realservers in a specific service) right now, rather than waiting for the next 15-second point. Is there any way to do this?

For us, this would be useful during deployment operations, where we want to have a new realserver health-checked and added to the pool right away, rather than waiting for it to happen naturally.

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I think this can be done by sending the HUP signal:

pkill -HUP keepalived
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I think that makes keepalived re-read is configuration file. Does that then cause an immediate health check? If it does, it will necessarily be a check of everything, which is not what i was asking for. – Tom Anderson Jun 7 '12 at 16:00
Of course HUP will do more than you were asking for, but why would rereading the configuration file and checking everything do any harm? Have you tried it? – Oliver Jun 8 '12 at 5:34

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