Why was LoadBalancerAlgorithm removed from configuration?

[schancel]

In April of 2017 the following PR was merged to add support for overriding the load balancing algorithm: #673

On the 28th of November, this PR was merged, deleting it saying that it's unused:
#3478

It's not clear to me that it was in fact unused. The documentation still references it:
https://github.com/kubernetes/ingress-nginx/blob/master/docs/user-guide/nginx-configuration/configmap.md#load-balance

@ElvinEfendi @aledbf @jeffpearce

[alexkursell]

@schancel It looks like we moved to specifying the load balancing algorithm per-ingress as an annotation, rather than globally as a configmap value. Looks like the docs never got updated to reflect that.

[schancel]

Thank you

[ElvinEfendi]

@schancel have you tried what's documented in there? It should work.

What was deleted is not about load-balance setting.

@alexkursell no, we should still have support for configuring load balancing algorithm globally.

[panpan0000]

@ElvinEfendi

the load-balance global config-map is not working.
when changed to 'ip_hash', the nginx.conf never gets updated.

here is my test:

[root@ingress-master-1 ~]# kubectl describe  cm -n kube-system   ingress01|grep load -A2
load-balance:
----
ip_hash
[root@ingress-master-1 ~]# kubectl exec -it -n kube-system  ingress01-687b55d6fd-lcdqf grep hash nginx.conf
	types_hash_max_size             2048;
	server_names_hash_max_size      1024;
	server_names_hash_bucket_size   64;
	map_hash_bucket_size            64;
	proxy_headers_hash_max_size     512;
	proxy_headers_hash_bucket_size  64;
	variables_hash_bucket_size      128;
	variables_hash_max_size         2048;

I'm based on v0.21, but checking the code ,seems no releavant fix from 0.21 to latest.
maybe you guys or @schancel can have a try.

[ElvinEfendi]

@panpan0000 are you following the note in the page?

ip_hash: to use a hash of the server for routing (note that this is available only in non-dynamic mode: --enable-dynamic-configuration=false, but alternatively you can consider using nginx.ingress.kubernetes.io/upstream-hash-by)

ip_hash is not supported in dynamic mode. And since 0.22.0 there's no non-dynamic mode, so I agree that the docs need an update regarding to ip_hash, but load-balance should work, if it does not then that's a bug.

Also in recent versions changing load-balance setting does not require Nginx reload. If you wanna inspect whether it was applied or not you can use ingress-nginx kubectl plugin and run

kubectl ingress-nginx backends --backend=<name of the backend>

to list the backend names

kubectl ingress-nginx backends --list

You can find more info about the plugin and how to install it at https://kubernetes.github.io/ingress-nginx/troubleshooting/, but it requires you use ingress-nginx version 0.23.0.

[alexkursell]

@schancel After talking with @ElvinEfendi in person it does look like the configmap value isn't being applied properly. I'll start working on a fix when I get the time. In the meantime, you can use the ingress annotation instead.

[panpan0000]

@alexkursell @ElvinEfendi Thank you both for the clarification !
Most appreciated . For some reason, I'm still using 0.21 for production, but will upgrade once this fix is done and try this amazing plugin.
Thank you again!

[panpan0000]

It's a pity. Since 0.21 is already dynamic-mode, so least_conn/ip_hash is not working.
only ewma left.

But when I add annotation to ingress instance as below

# kubectl describe  ingress my-l7  |grep Annotations -C 3
 Annotations:
  nginx.ingress.kubernetes.io/affinity:               cookie
  nginx.ingress.kubernetes.io/load-balance:           ewma
  nginx.ingress.kubernetes.io/proxy-connect-timeout:  100

The backend doesn't change at all. I expected the ewma weight or something will change from below status port API to reflect Lua changes, but no difference than what it was ( default round-robin)

curl localhost:18080/configuration/backends| jq '.'

[ElvinEfendi]

so least_conn/ip_hash is not working.

while least_conn support is lacking, there's an alternative for ip_hash: https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/annotations/#custom-nginx-upstream-hashing

he backend doesn't change at all

When you set affinity load-balance gets ignored. affinity of itself is a type of load balancing algorithm. If you remove affinity and change load-balance annotation and not see any difference in the backend configuration please create another issue with relevant details - that is not an expected behaviour.

[panpan0000]

@ElvinEfendi , Yes! when nginx.ingress.kubernetes.io/affinity: cookie annotation removed,
the "load-balance": "ewma", appears in the /configuration/backends API output.
Thank you for your patient for my silly questions !

[aledbf]

@alexkursell maybe ^^ is another possible validation