Kubernetes Multiple Path Rewrites - nginx

Question

Alright, various permutations of this question have been asked and I feel terrible asking; I'm throwing the towel in and was curious if anyone could point me in the right direction (or point out where I'm wrong). I went ahead and tried a number of examples from the docs, but to no avail (see below).
I'm trying to route traffic to the appropriate location under Kubernetes using an Ingress controller.
Server Setup
I have a server, myserver.com and three services running at:
myserver.com/services/
myserver.com/services/service_1/
myserver.com/services/service_2/
Note that I'm not doing anything (purposefully) to myserver.com/.
At each of the three locations, there's a webapp running. For example, myserver.com/services/service_2 needs to load css files at myserver.com/services/service_2/static/css, etc...
Kubernetes Ingress
To manage the networking, I'm using a Kubernetes Ingress controller, which I've defined below. The CORS annotations aren't super relevant, but I've included them to clear up any confusion.
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: myServices
namespace: myServices
annotations:
nginx.ingress.kubernetes.io/enable-cors: "true"
nginx.ingress.kubernetes.io/cors-allow-methods: "GET, POST, OPTIONS"
nginx.ingress.kubernetes.io/cors-allow-origin: '$http_origin'
nginx.ingress.kubernetes.io/cors-allow-credentials: "true"
nginx.ingress.kubernetes.io/rewrite-target: /
nginx.ingress.kubernetes.io/use-regex: "true"
spec:
ingressClassName: nginx
tls:
- hosts:
- myserver.com
rules:
- host: myserver.com
http:
paths:
- path: /services
pathType: Prefix
backend:
service:
name: web-service
port:
number: 80
- path: /services/service_1(/|$)
pathType: Prefix
backend:
service:
name: web-service-1
port:
number: 80
- path: /services/service_2(/|$)
pathType: Prefix
backend:
service:
name: web-service-2
port:
number: 80
Targets
I noticed that one helpful thing to do is give some path examples. From the examples below it looks like the paths aren't that complicated. I think this is what I'm after. Note that I'd like each service to be able to resolve its css and image files.
myserver.com/services -> myserver.com/services
myserver.com/services/xxx/xxx -> myserver.com/services/xxx/xxx
myserver.com/services/service_1 -> myserver.com/services/service_1
myserver.com/services/service_1/xxx/xxx -> myserver.com/services/service_1/xxx/xxx
myserver.com/services/service_2/xxx/xxx -> myserver.com/services/service_2/xxx/xxx
Attempts
I know that this issue has to do a lot with the nginx.ingress.kubernetes.io/rewrite-target rule and its interaction with the paths I've defined.
I know that I don't want nginx.ingress.kubernetes.io/rewrite-target: $1 because that gives a 500 when visiting myserver.com/services
I know that I don't want nginx.ingress.kubernetes.io/rewrite-target: $1/$2 because when I visit myserver.com/services/service_1 I actually get part of the content at myserver.com/services rendered on the page.
SO Attempt 1
I also attempted to replicate the accepted solution from this question.
In this attempt I set
nginx.ingress.kubernetes.io/rewrite-target: "/$1" and one of the service paths to
- path: /(services/service_1(?:/|$).*)
When I visit myserver.com/services/service_1/xyz, the HTML from myserver.com/services/service_1 gets rendered.
Concluding Thoughts
Something ain't quite right with the path rewrite and paths rules. Any suggestions?

Answer 1

The problem you reported in your most recent comment is resolved by looking at the rewrite example in the nginx-ingress documentation.
The rewrite-target annotation configures the ingress such that matching paths will be rewritten to that value. Since you've specified a static value of /, anything matching your ingress rules will get rewritten to /, which is exactly the behavior you're seeing.
The solution is to capture the portion of the path we care about, and then use that in the rewrite-target annotation. For example:
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: myservices
annotations:
nginx.ingress.kubernetes.io/enable-cors: "true"
nginx.ingress.kubernetes.io/cors-allow-methods: "GET, POST, OPTIONS"
nginx.ingress.kubernetes.io/cors-allow-origin: '$http_origin'
nginx.ingress.kubernetes.io/cors-allow-credentials: "true"
nginx.ingress.kubernetes.io/rewrite-target: /$2
nginx.ingress.kubernetes.io/use-regex: "true"
nginx.ingress.kubernetes.io/ssl-redirect: "false"
spec:
ingressClassName: nginx
rules:
- host: myserver.com
http:
paths:
- path: /services/service_1(/|$)(.*)
pathType: Prefix
backend:
service:
name: webservice-service1
port:
number: 80
- path: /services/service_2(/|$)(.*)
pathType: Prefix
backend:
service:
name: webservice-service2
port:
number: 80
- path: /services(/|$)(.*)
pathType: Prefix
backend:
service:
name: webservice
port:
number: 80
Here, we've modified the match expression so that they look like:
- path: /services/service_1(/|$)(.*)
The second capture group (.*) captures everything after the path
portion that matches literally. We then use that capture group ($2,
because it's the second group) in the rewrite-target annotation:
nginx.ingress.kubernetes.io/rewrite-target: /$2
With this configuration in place, a request to /services/service_2
results in:
This is service2.
But a request to /services/service_2/foo/bar results in:
<html><head><title>404 Not Found</title></head><body>
<h1>Not Found</h1>
The URL you requested (/foo/bar) was not found.
<hr>
</body></html>
And looking at the backend server logs, we see:
10.42.0.32 - - [21/Jan/2022:20:33:23 +0000] "GET / HTTP/1.1" 200 211 "" "curl/7.79.1"
10.42.0.32 - - [21/Jan/2022:20:33:45 +0000] "GET /foo/bar HTTP/1.1" 404 311 "" "curl/7.79.1"
I've updated my example repository to match this configuration.