Support load balancing with nginx dynamic upstreams

[subnetmarco]

Support for dynamic upstreams that will enable dynamic load balancing per API.

 # sample upstream block:
 upstream backend {
    server 127.0.0.1:12354;
    server 127.0.0.1:12355;
    server 127.0.0.1:12356 backup;
}

So we can proxy_pass like:

proxy_pass http://backend;

[bobrik]

I'd love to see that too. My use-case is routing requests to dynamic mesos tasks with zoidberg, kong would be a good candidate to do the routing part. I was going to use nginx with 2 ports anyway. Let me know if it makes sense to use kong for this.

Here are the options I see:

1. New Feature: added ngx_http_lua_upstream_set_peer_addr() openresty/lua-upstream-nginx-module#11 can be used to preallocate list of upstreams and only use some subset of that list
2. Hi,I pull a request for add_server to upstream,and include testing code openresty/lua-upstream-nginx-module#12 can be used for dynamic allocation of upstreams, but list can only grow, so previous PR is needed as well
3. https://twitter.com/agentzh/status/580170442150846464 — not public yet, needs manual handling of retry logic, but can replace both previous versions

Reloading nginx is not an option since it triggers graceful restart for all the worker processes. We use that mechanism with haproxy in marathoner, but long-lived sessions force previous instances of haproxy to stay alive for extended periods of time. Nginx is using more processes than haproxy, so it would be even worse. Deploying a lot can cause spinning thousands of proxying processes for no good reason.

[Tenzer]

Nginx can already do this in the Plus version: http://nginx.com/products/on-the-fly-reconfiguration/

[bobrik]

Yep, that's another option starting at $7000 annually for 5 servers.

[Tenzer]

You can also buy the license for one server at $1500 per year: http://nginx.com/products/pricing/. I'm not saying it's cheap or anything but it's an alternative if people wasn't aware of it.

[bobrik]

Another option: https://github.com/yzprofile/ngx_http_dyups_module

[bobrik]

Looks like dyups can do the trick: https://github.com/bobrik/zoidberg-nginx. Nginx config and lua scripts could give an idea how it works.

I'm not sure about stability of this thing, though.

[subnetmarco]

Just a quick update on this, this feature is important and we feel like an initial implementation should be done. It's not going to make it into 0.3.0 (currently working on implementing other major features, including SSL support and path-based routing), but it definitely should show up within the next two releases. We are trying to keep the release cycles very short, so it shouldn't take too much time.

Of course pull-requests are also welcome.

[bobrik]

Can you tell me how this is going to be implemented?

On Wednesday, May 20, 2015, Marco Palladino notifications@github.com
wrote:

Just a quick update on this, this feature is important and we feel like an
initial implementation should be done. It's not going to make it into
0.3.0 (currently working on implementing other major features, including
SSL support and path-based routing), but it definitely should show up
within the next two releases. We are trying to keep the release cycles very
short, so it shouldn't take too much time.

—
Reply to this email directly or view it on GitHub
#157 (comment).

Regards, Ian Babrou
http://bobrik.name http://twitter.com/ibobrik skype:i.babrou

[subnetmarco]

@bobrik As you pointed out in one of your links, apparently the creator of OpenResty is building a balancer_by_lua functionality which should do the job - so I am investigating this option.

The alternative is taking one of the existing pull requests on the lua-upstream module and contribute to them to make them acceptable and implement any missing feature we might need.