A `restart` - is naturally an unconditional step thats required - especially in cases of new backends or server additions therein - which are not trivial changes. Network loss / disturbance - if any - is negligible as any existing connections should be migrated between process with a minute window (relative to host) where new connection may not get a response, etc - though realistically in most modern x64 hosts and environments we're talking of < 10ms (least in my own case).
What may be a better option for you to consider is - having backup server instances / routes predefined that you can then adjust or change dynamically and perhaps even better control via `acl` related clauses which can also be changed dynamically without having to do a restart. This procedure can also work for load elastication - for example where you'd have at least 100% / duplicate number of server instances in each backend; also a similar approach may server for later fail-safes that have not yet been spawned or running but at least have a predefined route which can be adjusted with appropriate checks and server weighting without any further restart. I hope I've not misinformed you in anyway. On Thu, Feb 18, 2016 at 3:07 PM, <[email protected]> wrote: > Hello, > > What is the best way to dynamically add a new backend server (cluster > node) without causing traffic disruptions? In other words, after adding a > new 'server' line to backend section. Merely saving the configuration file > does not seem to cause HAProxy to re-read the configuration. My HAProxy > runs as a service. > > Thank you > Alex >
