GKE Ingres and GCE Load balancer : Always get 404 - kubernetes

I try to deploy 2 applications (behind 2 separates Deployments objects). I have 1 Service per Deployment, with type NodePort.
application1_service.yaml
apiVersion: v1
kind: Service
metadata:
name: application1-service
namespace: default
spec:
ports:
- port: 80
protocol: TCP
targetPort: 80
selector:
run: application1
type: NodePort
application2_service.yaml is the exact same (except for name and run)
I use an Ingress to make the 2 services available,
ingress.yaml
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: my-ingress
annotations:
kubernetes.io/ingress.global-static-ip-name: "my-static-ip"
networking.gke.io/managed-certificates: "my-certificate"
kubernetes.io/ingress.class: "gce"
spec:
rules:
- host: "my.host.com"
http:
paths:
- path: /*
backend:
serviceName: application1-service
servicePort: 80
- path: /application2/*
backend:
serviceName: application2-service
servicePort: 80
I also create a ManagedCertificate object, to be able to handle HTTPS requests.
managed_certificate.yaml
apiVersion: networking.gke.io/v1beta1
kind: ManagedCertificate
metadata:
name: my-certificate
spec:
domains:
- my.host.com
The weird thing here is that curl https://my.host.com/ works fine and I can access my service, but when I try curl https://my.host.com/application2/, I keep getting 404 Not Found.
Why is the root working and not the other ?
Additional info:
The ManagedCertificate is valid and works fine with /.
application1 and application2 are the exact same app and if I swap them in the ingress, the output is the same.
Thanks for your help !
EDIT:
Here is the 404 I get when I try to access application2
Don't know if it can help but here is also the part of the Ingress access logs showing the 404

i think you can't use the same port for 2 different applications because this port is used on every node to route to one app.
From docs:
NodePort: Exposes the Service on each Node's IP at a static port (the NodePort). A ClusterIP Service, to which the NodePort Service routes, is automatically created. You'll be able to contact the NodePort Service, from outside the cluster, by requesting :.
So in your case one app is already using port 80, you could try to use a different one for application 2

I have replicated the problem without a domain and managed a
Certificate. For me it's working fine using the Load Balancer IP
address.
(ingress-316204)$ curl http://<LB IP address>/v2/
Hello, world!
Version: 2.0.0
Hostname: web2-XXX
(ingress-316204)$ curl http://<LB IP address>/
Hello, world!
Version: 1.0.0
Hostname: web-XXX
Ingress configuration seems to be correct as per doc. Check if curl https://LB IP address/application2/ is working or not, if it's working then there might be some issue with the host name.
Check if you have updated the host file (/etc/hosts) with line LB IP
address my.host.com.
Check if host, path and backend are configured correctly in Load
Balancer configuration.
If still having the problem then check Port,Nodeport and Targetport configured correctly or else share the output of ‘kubectl describe ing my-ingress’ for further investigation.

Answering my own question:
After searching for days, I ultimately found the reason of the problem.
Everything was fine with the cluster and the configs, my problem was from my Flask API.
All the URLs was like this one:
#app.route("/my_function")
So it was working fine on root path with my.host.com/my_function, but when I was typing my.host.com/application1/my_function it wasn't working...
I just changed my app to
#app.route("/application1/my_function")
Everything works fine now :) Hope it will help !

Related

Kubernetes networking confusion on google cloud

I'm fairly new to Kubernetes and I have played around with it for a few days now to get a feeling for it. Trying out to set up an Nginx Ingress controller on the google-cloud platform following this guide, I was able to set everything up as written there - no problems, I got to see the hello-app output.
However, when I tried replicating this in a slightly different way, I encountered a weird behavior that I am not able to resolve. Instead of using the image --image=gcr.io/google-samples/hello-app:1.0 (as done in the tutorial) I wanted to deploy a standard nginx container with a custom index page to see if I understood stuff correctly. As far as I can tell, all the steps should be the same except for the exposed port: While the hello-app exposes port 8080 the standard port for the nginx container is 80. So, naively, I thought exposing (i.e., creating a service) with this altered command should do the trick:
kubectl expose deployment hello-app --port=8080 --target-port=80
where instead of having target-port=8080 as for the hello-app, I put target-port=80. As far as I can tell, all other thins should stay the same, right? In any way, this does not work and when I try to access the page I get a "404 - Not Found" although the container is definitely running and serving the index page (I checked by using port forwarding from the google cloud which apparently directly makes the page accessible for dev purposes). In fact, I also tried several other combinations of ports (although I believe the above one should be the correct one) to no avail. Can anyone explain to my why the routing does not work here?
If you notice the tutorial inside the ingress configuration path: "/hello"
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: ingress-resource
annotations:
kubernetes.io/ingress.class: "nginx"
nginx.ingress.kubernetes.io/ssl-redirect: "false"
spec:
rules:
- host: "34.122.88.204.nip.io"
http:
paths:
- pathType: Prefix
path: "/hello"
backend:
service:
name: hello-app
port:
number: 8080
you might have updated port number and service name config however if path /hello which means you request is going to Nginx container but not able to file the page hello.html so it's giving you 404.
You hit endpoint IP/hello (Goes to Nginx ingress controller)-->
checked for path /hello and forwarded request to service -->
hello-app (service forwarded request to PODs) --> Nginx POD (it
doesn't have anything at path /hello so 404)
404 written by Nginx side, in your case either it will be Nginx ingress controller or else container(POD) itself.
So try you ingress config without setting path path: "/" and hit the endpoint you might see the output from Nginx.

Nginx Ingress returns 502 Bad Gateway on Kubernetes

I have a Kubernetes cluster deployed on AWS (EKS). I deployed the cluster using the “eksctl” command line tool. I’m trying to deploy a Dash python app on the cluster without success. The default port for Dash is 8050. For the deployment I used the following resources:
pod
service (ClusterIP type)
ingress
You can check the resource configuration files below:
pod-configuration-file.yml
kind: Pod
apiVersion: v1
metadata:
name: dashboard-app
labels:
app: dashboard
spec:
containers:
- name: dashboard
image: my_image_from_ecr
ports:
- containerPort: 8050
service-configuration-file.yml
kind: Service
apiVersion: v1
metadata:
name: dashboard-service
spec:
selector:
app: dashboard
ports:
- port: 8050 # exposed port
targetPort: 8050
ingress-configuration-file.yml (host based routing)
kind: Ingress
metadata:
name: dashboard-ingress
annotations:
nginx.ingress.kubernetes.io/ssl-redirect: "false"
nginx.ingress.kubernetes.io/force-ssl-redirect: "false"
nginx.ingress.kubernetes.io/rewrite-target: /
spec:
rules:
- host: dashboard.my_domain
http:
paths:
- backend:
serviceName: dashboard-service
servicePort: 8050
path: /
I followed the steps below:
kubectl apply -f pod-configuration-file.yml
kubectl apply -f service-configuration-file.yml
kubectl apply -f ingress-confguration-file.yml
I also noticed that the pod deployment works as expected:
kubectl logs my_pod:
and the output is:
Dash is running on http://127.0.0.1:8050/
Warning: This is a development server. Do not use app.run_server
in production, use a production WSGI server like gunicorn instead.
* Serving Flask app "annotation_analysis" (lazy loading)
* Environment: production
WARNING: This is a development server. Do not use it in a production deployment.
Use a production WSGI server instead.
* Debug mode: on
You can see from the ingress configuration file that I want to do host based routing using my domain. For this to work, I have also deployed an nginx-ingress. I have also created an “A” record set using Route53
that maps the “dashboard.my_domain” to the nginx-ingress:
kubectl get ingress
and the output is:
NAME HOSTS ADDRESS. PORTS. AGE
dashboard-ingress dashboard.my_domain nginx-ingress.elb.aws-region.amazonaws.com 80 93s
Moreover,
kubectl describe ingress dashboard-ingress
and the output is:
Name: dashboard-ingress
Namespace: default
Address: nginx-ingress.elb.aws-region.amazonaws.com
Default backend: default-http-backend:80 (<error: endpoints "default-http-backend" not found>)
Rules:
Host Path Backends
---- ---- --------
host.my-domain
/ dashboard-service:8050 (192.168.36.42:8050)
Annotations:
nginx.ingress.kubernetes.io/force-ssl-redirect: false
nginx.ingress.kubernetes.io/rewrite-target: /
nginx.ingress.kubernetes.io/ssl-redirect: false
Events: <none>
Unfortunately, when I try to access the Dash app on the browser, I get a
502 Bad Gateway error from the nginx. Could you please help me because my Kubernetes knowledge is limited.
Thanks in advance.
It had nothing to do with Kubernetes or AWS settings. I had to change my python Dash code from:
if __name__ == "__main__":
app.run_server(debug=True)
to:
if __name__ == "__main__":
app.run_server(host='0.0.0.0',debug=True).
The addition of host='0.0.0.0' did the trick!
I think you'll need to check whether any other service is exposed at path / on the same host.
Secondly, try removing rewrite-target annotation. Also can you please update your question with output of kubectl describe ingress <ingress_Name>
I would also suggest you to use backend-protocol annotation with value as HTTP (default value, you can avoid using this if dashboard application is not SSL Configured, and only this application is served at the said host.) But, you may need to add this if multiple applications are served at this host, and create one Ingress with backend-protocol: HTTP for non SSL services, and another with backend-protocol: HTTPS to serve traffic to SSL enabled services.
For more information on backend-protocol annotation, kindly refer this link.
I have often faced this issue in my Ingress Setup and these steps have helped me resolve it.

Expose pod's tomcat port

I have the bare metall kubernetes pod running tomcat application on port 8085. If it would be common server, the app would be accessible via http://<server-ip>:8085/app. My goal is to expose the tomcat on Kubernetes node's address and the same port as used in tomcat.
I am able to expose and access app using Node Port service - but it is inconvenient that port is always different.
I tried to setup traefik ingress:
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: test-tag2
spec:
rules:
- host: kubernetes.example.com #in my conf I use node's domain name
http:
paths:
- path: /test
backend:
serviceName: test-tag2
servicePort: 8085
And I can see result in Traefik's dashboard, but still if I navigate to http://kubernetes.example.com/test/app I get nothing.
I've tried a bunch of ways to configure that and still no luck.
Is it actually possible to expose my pod in this way?
Did you try specifying a nodePort value in the service yaml? If specified, kubernetes will create service on the specified NodePort. If the nodePort is not available , kubernetes doesn't create the service.
Refer to this answer for more details:
https://stackoverflow.com/a/43944385/1237402

How to send data from a container within a Pod, to a container within a separate Pod - within the same cluster?

I have a React frontend and a node.js backend. Each are in separate containers within separate Pods within the same cluster in k8's.
I want to send data between them without having to use IP addresses. I know Kubernetes has a feature that lets you talk between pods inside the same cluster, and i think its related to the selector label defined within the Service files created.
I have created a ClusterIp service for my React app and another ClusterIp for my server. I have created an ingress file for my application. I know my ingress works as i can access my UI, and i can hit my health check endpoint of my server - so i know they are exposed to the outside world correctly. My problem is how to communicate internally within k8's
Within the my react app i have tried to write
axios.post("/api/test", {
value: "TestValue"
});
But the endpoint within my server of api/test never gets hit with this.
Backend Server Cluster IP - - - - 
 
apiVersion: v1
kind: Service
metadata:
name: server-model-cluster-ip-service
spec:
type: ClusterIP
selector:
component: server-model
ports:
- port: 8050
targetPort: 8050
React UI Cluster IP - - - -
apiVersion: v1
kind: Service
metadata:
name: react-ui-cluster-ip-service
spec:
type: ClusterIP
selector:
component: react-ui
ports:
- port: 3000
targetPort: 3000 
Ingress File - - - - -
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: ingress-service
annotations:
kubernetes.io/ingress.class: nginx
nginx.ingress.kubernetes.io/rewrite-target: /$1
spec:
rules:
- http:
paths:
- path: /api/?(.*)
backend:
serviceName: react-ui-cluster-ip-service
servicePort: 8050
- path: /server/?(.*)
backend:
serviceName: server-model-cluster-ip-service
servicePort: 8050
I understand the Label selector is what maps my React Cluster IP to the Deployment for my UI and similar for my Server Cluster IP to my Deployment for server. I thin i am right in saying i can use the selector somehow to send axis/http requests to other pods like..
axios.post("/PODNAME/api/test", {
value: "TestValue"
});
Could anyone tell me if i am completely wrong or missing something obvious please :)
Here in this part of ingress service name react-ui-cluster-ip-service is there which is running on port 3000 as you mention in service spec file.
But in you are you are sending traffic to proper service name but the port is wrong one.
- path: /api/?(.*)
backend:
serviceName: react-ui-cluster-ip-service
servicePort: 8050
I think due to this you are not able to send request to /api/?
From your service spec file you can also remove type:clusterIP and you can use an only service name to resolve the services inside kubernetes cluster.
answer for your question title: containers with pod can talk on localhost while container within separtate pod can talk over the service name there no need add the service type as clusterIP & Nodeport
I have few concerns here.
As #Harsh Manvar mentioned in his answer, Kubernetes represents mechanism of discovering internal services which guarantees intercommunication between Pods within the same cluster either by IP address or relevant DNS name of service.Therefore you might be able to reach your backend server from particular frontend Pod without involving Ingress, as Ingress controller stays as an edge router and exposes HTTP and HTTPS network traffic from outside the cluster to the corresponded Kubernetes services.
You also used rewrite expression enclosed to your specific path based routing rules within Ingress object. In that scenario the rewrite seems to be resulted in the following way: server-model-cluster-ip-service/api/test rewrites to server-model-cluster-ip-service/test URI and this should be final path placeholder for you backend service. In fact that you are invoking axios.post("server-model-cluster-ip-service/api/test", { value: "TestValue" }) request from React UI Pod might not hit the target backend service.
I just gave some points to consider how to proceed with further troubleshooting, at least you can log into the frontend Pod and check the connectivity to the target backend service accordingly.

How do I make my admin ui of cockroachdb publicly available via traefik ingress controller on kubernetes?

Kubernetes dedicated cockroachdb node - accessing admin ui via traefik ingress controller fails - page isn't redirecting properly
I have a dedicated kubernetes node running cockroachdb. The pods get scheduled and everything is setup. I want to access the admin UI from a subdomain like so: cockroachdb.hostname.com. I have done this with traefik dashboard and ceph dashboard so I know my ingress setup is working. I even have cert-manager running to have https enabled. I get the error from the browser that the page is not redirecting properly.
Do I have to specify the host name somewhere special?
I have tried adding this with no success: --http-host cockroachdb.hostname.com
This dedicated node has its own public ip which is not mapped to hostname.com. I think I need to change a setting in cockroachdb, but I don't know which because I am new to it.
Does anyone know how to publish admin UI via an ingress?
EDIT01: Added ingress and service config files
Ingress:
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: cockroachdb-public
annotations:
kubernetes.io/ingress.class: traefik
traefik.frontend.rule.type: PathPrefixStrip
certmanager.k8s.io/issuer: "letsencrypt-prod"
certmanager.k8s.io/acme-challenge-type: http01
ingress.kubernetes.io/ssl-redirect: "true"
ingress.kubernetes.io/ssl-temporary-redirect: "true"
ingress.kubernetes.io/ssl-host: "cockroachdb.hostname.com"
traefik.frontend.rule: "Host:cockroachdb.hostname.com,www.cockroachdb.hostname.com"
traefik.frontend.redirect.regex: "^https://www.cockroachdb.hostname.com(.*)"
traefik.frontend.redirect.replacement: "https://cockroachdb.hostname.com/$1"
spec:
rules:
- host: cockroachdb.hostname.com
http:
paths:
- path: /
backend:
serviceName: cockroachdb-public
servicePort: http
- host: www.cockroachdb.hostname.com
http:
paths:
- path: /
backend:
serviceName: cockroachdb-public
servicePort: http
tls:
- hosts:
- cockroachdb.hostname.com
- www.cockroachdb.hostname.com
secretName: cockroachdb-secret
Serice:
apiVersion: v1
kind: Service
metadata:
# This service is meant to be used by clients of the database. It exposes a ClusterIP that will
# automatically load balance connections to the different database pods.
name: cockroachdb-public
labels:
app: cockroachdb
spec:
ports:
# The main port, served by gRPC, serves Postgres-flavor SQL, internode
# traffic and the cli.
- port: 26257
targetPort: 26257
name: grpc
# The secondary port serves the UI as well as health and debug endpoints.
- port: 8080
targetPort: 8080
name: http
selector:
app: cockroachdb
EDIT02:
I can access the Admin UI page now but only by going over the external ip address of the server with port 8080. I think I need to tell my server that its ip address is mapped to the correct sub domain?
EDIT03:
On both scheduled traefik-ingress pods the following logs are created:
time="2019-04-29T04:31:42Z" level=error msg="Service not found for default/cockroachdb-public"
Your referencing looks good on the ingress side. You are using quite a few redirects, unless you really know what each one is accomplishing, don't use them, you might end up in an infinite loop of redirects.
You can take a look at the following logs and methods to debug:
Run kubectl logs <traefik pod> and see the last batch of logs.
Run kubectl get service, and from what I hear, this is likely your main issue. Make sure your service exists in the default namespace.
Run kubectl port-forward svc/cockroachdb-public 8080:8080 and try connecting to it through localhost:8080 and see terminal for potential error messages.
Run kubectl describe ingress cockroachdb-public and look at the events, this should give you something to work with.
Try accessing the service from another pod you have running ping cockroachdb-public.default.svc.cluster.local and see if it resolves the IP address.
Take a look at your clusterrolebindings and serviceaccount, it might be limited and not have permission to list services in the default namespace: kubectl create clusterrolebinding default-admin --clusterrole cluster-admin --serviceaccount=default:default