I created an headless service:
apiVersion: v1
kind: Service
metadata:
name: myapp-service-headless
spec:
ports:
- port: 80
selector:
app: myapp
clusterIP: None
From Kubernetes dashboard I can see its Internal endpoints:
myapp-service-headless:80 TCP
myapp-service-headless:0 TCP
In this application, I also set internal endpoint to:
http://myapp-service-headless
But from outside, how can I access its IP to connect API?
For example, my Kubernetes' IP is 192.168.99.100, then connect to 192.168.99.100 is okay?
Now the service status from Kubernetes dashboard
Services
Service Details
There is two option to expose the service outside, you can use the ingress controller to connect to the server.
The simple method is change your service type to NodePort, then you should be able access server using NodeIP and service external port number.
here is the more info.
https://kubernetes.io/docs/concepts/services-networking/service/#type-nodeport
Related
I'm trying to use a load balancer to expose a service I have running on an EKS pod. My service is defined in a yaml like this:
kind: Service
apiVersion: v1
metadata:
name: mlflow-server
namespace: default
labels:
app: mlflow-server
annotations:
service.beta.kubernetes.io/aws-load-balancer-type: nlb
spec:
externalTrafficPolicy: Local
type: LoadBalancer
selector:
app: mlflow-server
ports:
- name: http
port: 88
targetPort: http
- name: https
port: 443
targetPort: https
This is to define a service for a pod that I have mlflow server running on. When I apply this and access the external IP generated for the service, I get a This site can’t be reached webpage error. Is there something I'm missing with exposing my service as a load balanced service to access the mlflow ui?
For a basic Loadbalancer type service you do not need the annotation service.beta.kubernetes.io/aws-load-balancer-type: nlb this creates the network load balancer. Now if you need it to be an NLB then there might be following problems:
The nlb takes few minutes to come up when you apply the setting. If you check it just after you deploy it it will not be able to accept the traffic. Please do check if the intended network loadbalancer is up in your AWS-EC2console > Loadbalancer tab.
The second problem that is more likely to happen is that the NLB is can be attached with only some instance types only. To check that you can go through the following link.
https://docs.aws.amazon.com/elasticloadbalancing/latest/network/target-group-register-targets.html#register-deregister-targets
So if you actually do not have the need of network loadbalancer remove the annotation as the nlb has an higher charge as well. But, if that is the dire requirement do check with the second option if the instances that you are using on AWS are compatible with Network LoadBalancer.
Suppose if I have 3 node Kafka cluster setup. Then how do I expose it outside a cloud using Load Balancer service? I have read reference material but have a few doubts.
Say for example below is a service for a broker
apiVersion: v1
kind: Service metadata:
name: kafka-0
annotations: dns.alpha.kubernetes.io/external: kafka-0.kafka.my.company.com
spec:
externalTrafficPolicy: Local
type: LoadBalancer
ports:
- port: 9092
name: outside
targetPort: 9092
selector: app: kafka kafka-pod-id: "0"
What is port and targetPort?
Do I setup LoadBalancer service for each of the brokers?
Do these multiple brokers get mapped to single public IP address of cloud LB?
How does a service outside k8s/cloud access individual broker? By using public-ip:port? or by using kafka-<pod-id>.kafka.my.company.com:port?. Also which port is used here? port or targetPort?
How do I specify this configuration in Kafka broker's Advertised.listeners property? As port can be different for services inside k8s cluster and outside it.
Please help.
Based on the information you provided I will try give you some answers, eventually give some advise.
1) port: is the port number which makes a service visible to other services running within the same K8s cluster. In other words, in case a service wants to invoke another service running within the same Kubernetes cluster, it will be able to do so using port specified against port in the service spec file.
targetPort: is the port on the POD where the service is running. Your application needs to be listening for network requests on this port for the service to work.
2/3) Each Broker should be exposed as LoadBalancer and be configured as headless service for internal communication. There should be one addiational LoadBalancer with external ip for external connection.
Example of Service
apiVersion: v1
kind: Service
metadata:
name: kafka-0
annotations: dns.alpha.kubernetes.io/external: kafka-0.kafka.my.company.com
spec:
ports:
- port: 9092
name: kafka-port
protocol: TCP
selector:
pod-name: kafka-0
type: LoadBalancer
4) You have to use kafka-<pod-id>.kafka.my.company.com:port
5) It should be set to the external addres so that clients can connect to it. This article might help with understanding.
Similar case was on Github, it might help you also - https://github.com/kow3ns/kubernetes-kafka/issues/3
In addition, You could also think about Ingress - https://tothepoint.group/blog/accessing-kafka-on-google-kubernetes-engine-from-the-outside-world/
I've installed minikube to learn kubernetes a bit better.
I've deployed some apps and services which have ip's in a range of 10.x.x.x (private ip). I can expose my services on minikube and visit them in my browser. But I want to use the private IP's and not exposing it.
How can I visit (vpn/proxy wize) private ip's of services in minikube?
Minikube is Kubernetes with only one node and master server running on this node.
It provides the possibility to learn how it works with minimum hardware required.
It's ideal for testing purposes and seamless running on a laptop. Minikube is still software with mature
network stack from Kubernetes. This means that ports are exposed to services and virtually services are
communicating with pods.
To understand what is communicating, let me explain what ClusterIP does - it exposes the service on an internal IP in the cluster. This type makes service only reachable from within the cluster.
Cluster IP you can get by the command:
kubectl get services test_service
So, after you create a new service, you like to establish connections to ClusterAPI.
Basically, there are three ways to connect to backend resource:
1/ use kube-proxy - this proxy reflects services as defined in the Kubernetes API and simple stream TCP and UDP to backend or set of them in advanced configuration. Service cluster IPs and ports are currently found through Docker compatible environment variables specifying ports opened by the service proxy. There is an optional addon that provides cluster DNS for these cluster IPs. The user must create a service with the apiserver API to configure the proxy.
Example shows how can we use nodeselectors to define connection to port 5000 on ClusterIP - config.yaml may consist of:
kind: Service
apiVersion: v1
metadata:
name: jenkins-discovery
namespace: ci spec:
type: ClusterIP
selector:
app: master
ports:
- protocol: TCP
port: 50000
targetPort: 50000
name: slaves
2/ use port forwarding to access application - first check if kubectl command-line tool to communicate with your minikube cluster works, then if true find service port from ClusterIP configuration.
kubectl get svc | grep test_service
Let assume service test_service works on port 5555 so to do port forwarding run the command:
kubectl port-forward pods/test_service 5555:5555
After that, you service will be available on the localhost:5555
3/ If you are familiar with the concept of pods networking you cat declare public ports in the pod’s manifest file. A user can connect to pods network defining manifest:
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 8080
When the container is starting with manifest file like above host port TCP port 8080 will be forwarded to pod port 8080.
Please keep in the mind that ClusterIP is the use of a lot of services regarding to proper works of the cluster. I think it is not good practice to deal with ClusterIP as a regular network service - on worst scenario, it breaks a cluster soon, by invalid internal network state of connections.
I use Google Container Engine with Kubernetes.
I have created an https load balancer which terminates ssl and forwards traffic to k8s cluster nodes. The problem is I see no option to whitelist/filter incoming ip addresses. Is there any?
It sounds like you've set up a load balancer outside of Kubernetes. You may want to consider using a Kubernetes Service set to type: LoadBalancer. That type of service will give you an external IP that load balances to all of your Pods and can be easily restricted to whitelist IPs using the loadBalancerSourceRanges setting. Here is the example from the docs at https://kubernetes.io/docs/tasks/access-application-cluster/configure-cloud-provider-firewall/
apiVersion: v1
kind: Service
metadata:
name: myapp
spec:
ports:
- port: 8765
targetPort: 9376
selector:
app: example
type: LoadBalancer
loadBalancerIP: 79.78.77.76
loadBalancerSourceRanges:
- 130.211.204.1/32
- 130.211.204.2/32
If you're using gce controller is not yet possible[1], just nginx controller[2] accept whitelist ip.
[1] https://github.com/kubernetes/ingress/issues/566
[2] https://github.com/kubernetes/ingress/blob/188c64aaac17ef29400e0f143b9aed7770e32fee/controllers/nginx/configuration.md#whitelist-source-range
I'm running a bare metal Kubernetes cluster and trying to use a Load Balancer to expose my services. I know typically that the Load Balancer is a function of the underlying public cloud, but with recent support for Ingress Controllers it seems like it should now be possible to use nginx as a self-hosted load balancer.
So far, i've been following the example here to set up an nginx Ingress Controller and some test services behind it. However, I am unable to follow Step 6 which displays the external IP for the node that the load balancer is running on as my node does not have an ExternalIP in the addresses section, only a LegacyHostIP and InternalIP.
I've tried manually assigning an ExternalIP to my cluster by specifying it in the service's specification. However, this appears to be mapped as the externalID instead.
How can I manually set my node's ExternalIP address?
This is something that is tested and works for an nginx service created on a particular node.
apiVersion: v1
kind: Service
metadata:
name: nginx
namespace: default
spec:
ports:
- port: 80
protocol: TCP
targetPort: 80
name: http
- port: 443
protocol: TCP
targetPort: 443
name: https
externalIPs:
- '{{external_ip}}'
selector:
app: nginx
Assumes an nginx deployment upstream listening on port 80, 443.
The externalIP is the public IP of the node.
I would suggest checking out MetalLB: https://github.com/google/metallb
It allows for externalIP addresses in a baremetal cluster using either ARP or BGP. It has worked great for us and allows you to simply request a LoadBalancer service like you would in the cloud.