Kuberenetes newbie here, we have a jms server outside the cluster thats only accessible through our cluster, how can I create a port forward proxy on the cluster so I can connect to it via my local pc?
Proxy is an application layer function or feature, whereas port forwarding is really just a manual entry in one of the NAPT tables. A proxy understands the application protocol and can be used as a single entry point for multiple exposed servers.
The NGINX Ingress Controller for Kubernetes (as a proxy) is compatible with the NGINX web server. If you want to access workloads that are already running on your cluster from outside of it. Creating an Ingress resource is the standard procedure. In your workload cluster, add an ingress controller. For installation instructions, see this page.
Kubernetes port forwarding:
This is especially useful when you want to directly communicate with a specific port on a Pod from your local machine, according to the official kubernetes Connect with Port Forwarding documentation. Additionally, you don't have to manually expose services to accomplish this. Kubectl port-forward, on the other hand, moves connections from a local port to a pod port. Kubectl port-forward is more general than kubectl proxy because it can forward TCP traffic while kubectl proxy can only forward HTTP traffic. Although Kubectl simplifies port forwarding, it should only be utilized for debugging.
You can learn more about how to use port-forward to access applications in a cluster and another similar info link & SO aids in better comprehension.
Finally, for more information, see Port-Forwarding and Proxy Server and Client Deployment.
Related
I have set up a kubernetes cluster using kubeadm on a server, which is using an ingress controller (nginx) and this is working as intended. However, I used to deploy a nginx reverse proxy when I was using docker and to forward traffic to the containers. I have read that the ingress controller embarks a reverse proxy but I am not sure if it is sufficient and how to configure it (like IP ban when too many requests are sent in 1 s, ...).
I am aware that it can be done by modifying the port of the cluster and forwarding the traffic from the reverse proxy to the ingress controller but I don't know if it has any utility.
If you have more control over your inbound traffic, you can test multiple ingresses, not only Nginx. It will depend on the purpose of your requirement, although Nginx supports rate-limit. I suggest test others ingresses but try to install metal-lb firstly. So you can assign a specific Loadbalancer IP for each ingress.
I have a Kubernetes cluster with an on-demand auto-scaler to provide easily scaleable VM instances.
I want to provide SSH access (port 22) to the machines created within them behind a single ingress controller.
Example:
ssh poda.example.com:22 it should provide an ssh connection to pod A
ssh podb.example.com:22 it should provide an ssh connection to pod B
Another Example of UDP: There are two deployments of Redis within the cluster in two different namespaces. within the cluster, we are able to separate them using their service name. but outside the cluster we are not able to separate them
Expected Behaviour
redis-staging.example.com:6379 should connect to Redis in staging namespace
redis-prod.example.com:6379 it should connect to Redis in production namespace
I was using the Nginx ingress controller to open the port via a load-balancer to provide ssh access using the https://kubernetes.github.io/ingress-nginx/user-guide/exposing-tcp-udp-services/ documentation.
Challenge is that this directly bypasses the requirement of the sub-domain part and connects one port to one pod only. even a non-existing sub-domain can connect to the one pod linked to the port exposed.
How can I implement the desired behavior with Nginx or any other Ingress controller?
I have a Kubernetes cluster which doesn't need to expose ports to the public. I am installing monitoring and logging (Prometheus & Loki or Elastic) for in house use and would like to use their GUI. I could provision https ingress and limit IP access but port forwarding seems to work.
How Does port forwarding work, under the hood?
Is port forwarding as secure as my kubectl connection?
Is the connection as fast as an ingress load balancer based HTTPs connection?
In Kubernetes documentation you can find information that port-forward command allows you to access and interact with internal Kubernetes cluster processes from your localhost. Also it's one of the best tools to debugging.
Forward one or more local ports to a pod. This command requires the node to have 'socat' installed.
Use resource type/name such as deployment/mydeployment to select a pod. Resource type defaults to 'pod' if omitted.
If there are multiple pods matching the criteria, a pod will be selected automatically. The forwarding session ends when the selected pod terminates, and rerun of the command is needed to resume forwarding.
1. How Does port forwarding work, under the hood?
This information can be found in How Does Kubernetes Port Forwarding Work? article.
The whole process is simplified by the fact that kubectl already has a built-in port forwarding functionality.
A user interacts with Kubernetes using the kubectl command-line on their local machine.
The port-forward command specifies the cluster resource name and defines the port number to port-forward to.
As a result, the Kubernetes API server establishes a single HTTP connection between your localhost and the resource running on your cluster.
The user is now able to engage that specific pod directly, either to diagnose an issue or debug if necessary.
Port forwarding is a work-intensive method. However, in some cases, it is the only way to access internal cluster resources.
2. Is port forwarding as secure as my kubectl connection?
For this question, you can find answer in Is kubectl port-forward encrypted?. As pointed by #iomv
As far as I know when you port-forward the port of choice to your machine kubectl connects to one of the masters of your cluster so yes, normally communication is encrypted. How your master communicate to the pod though is dependent on how you set up internal comms.
or #neokyle
kubectl port-forward uses socat to make an encrypted TLS tunnel with port forwarding capabilities. The tunnel goes from you to the kube api-server to the pod so it may actually be 2 tunnels with the kube api-server acting as a pseudo router.
Kubecelt port-forward is encrypted.
3. Is the connection as fast as an ingress load balancer based HTTPs connection
As connection is inside the cluster, it should be faster than connection from outside the cluster to the cluster.
In addition, there was similar Stackoverflow thread about kubectl port-forward.
As various google articles(Example : this blog) states that this(connecting Kube cluster through proxy and clusterIP) method isn’t suitable for a production environment, but it’s useful for development.
My question is why it is not suitable for production ? Why connecting through nodeport service is better than proxy and clusterIP ?
Lets distinguish between three scenarios where connecting to the cluster is required
Connecting to Kubernetes API Server
Connecting to the API server is required for administrative purposes. The users of your application have no business with it.
The following options are available
Connect directly to Master IP via HTTPS
Kubectl Proxy Use kubectl proxy to to make the Kubernetes API available on your localhost.
Connecting external traffic to your applications running in the Kubernetes Cluster. Here you want to expose your applications to your users. You'll need to configure a Service and they can be of the following types
NodePort: Only accessible on the NodeIPs and ports > 30000
ClusterIP: Internal Only. External traffic cannot hit a service of type ClusterIP directly. Requires ingress resource & ingress controller to receive external traffic.
LoadBalancer: Allows you receive external traffic to one and only one service
Ingress: This isn't a type of service, it is another type of Kubernetes resource. By configuring NGINX Ingress for example, you can handle traffic to multiple ClusterIP services with only on external LoadBalancer.
A Developer needs to troubleshoot a pod/service: kubectl port-forward: Port forwarding example Requires kubectl to be configured on the system hence it cannot be used for all users of the application
As you can see from the above explanation, the proxy and port-forwarding option aren't viable options for connecting external traffic to the applications running because it requires your kubectl installed and configured with a valid kubeconfig which grants access into your cluster.
I couldn't find any information on wherever a connection creation between cluster's pod and locahost is encrypted when running "kubectl port-forward" command.
It seems like it uses "socat" library which supports encryption, but I'm not sure if kubernetes actually uses it.
As far as I know when you port-forward the port of choice to your machine kubectl connects to one of the masters of your cluster so yes, normally communication is encrypted. How your master communicate to the pod though is dependent on how you set up internal comms.
kubectl port-forward uses socat to make an encrypted TLS tunnel with port forwarding capabilities.
The tunnel goes from you to the kube api-server to the pod so it may actually be 2 tunnels with the kube api-server acting as a pseudo router.
An example of where I've found it useful was that I was doing a quick PoC of a Jenkins Pipeline hosted on Azure Kubernetes Service and earlier in my Kubernetes studies I didn't know how to setup an Ingress, but I could reach the Server via port 80 unencrypted, but I knew my traffic could be snooped on. So I just did kubectl port-forward to temporarily login and securely to debug my POC. Also really helpful with RabbitMQ Cluster hosted on Kubernetes, you can go into the management webpage with kubectl port-forward and make sure that it's clustering the way you wanted it to.