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I have checked your windows server version. you are using windows server 2016 (1607 version). since you are using the 1607 version you cant use WSL, Hyper-V, LinuxKit, Docker Desktop to run the Linux container image i.e (node, alpine, Nginx, etc..)

Please refer this StackOverflow question. you will find the solution.

The Docker container uses the OS kernel to run. Your problem is that the node container requires a Linux kernel and you are using a Windows NT kernel.

On Windows versions < 1709, you cannot use: WSL, Hyper-V, LinuxKit, Docker Desktop to solve the problem.

Working method, but with a big loss of performance:

1. Install Qemu, VMware or VirtualBox.
2. Install in virtual machine any Linux server distribution (e.g. Debian).
3. Then install Docker and Docker Compose: apt install -y docker docker.io docker-compose.
4. Now you can run any Linux container:)

After spending a fair amount of time I didn't find a way to fix the Windows does not support host IP addresses in NAT settings error nor using any other network / driver (bridge, host, etc). However, I found a workaround to make the port exposed only on the local machine by configuring the Kestrel web server of the web app (container) using the "AllowedHosts" parameter in the appsettings.json. I set the parameter value like below:

It seems you do not use the Azure Container Instance, you just run the container in the Windows VM. If I am right, the best way to make the container accessible outside is to run the container without setting the network, just need to map the port to the host port. Then the container is accessible outside with the exposed port. Here is the example command:

The base image you are requesting (mcr.microsoft.com/windows:2009) is not compatible with underlying Docker backend pre-installed on windows-latest runners. If you look at docker version/info output you can see those values:

According to kubernetes documentation the list of supported host operating systems is as follows:

• Ubuntu 16.04+
• Debian 9+
• CentOS 7
• Red Hat Enterprise Linux (RHEL) 7
• Fedora 25+
• HypriotOS v1.0.1+
• Flatcar Container Linux (tested with 2512.3.0)

This article mentioned that there are network issues on RHEL 8:

(2020/02/11 Update: After installation, I keep facing pod network issue which is like deployed pod is unable to reach external network or pods deployed in different workers are unable to ping each other even I can see all nodes (master, worker1 and worker2) are ready via kubectl get nodes. After checking through the Kubernetes.io official website, I observed the nfstables backend is not compatible with the current kubeadm packages. Please refer the following link in “Ensure iptables tooling does not use the nfstables backend”.

The simplest solution here is to reinstall the node on supported operating system.

The issue due to multiple reasons, Did following changes to fix

• Increased CPU cores (The CPU reaches 100% while performing docker build operation, Due to this container got exit in between).
• While performing docker build used the "--memory=16g" parameter. Refer to Runtime options with Memory, CPUs, and GPUs for more details.
• Application EXE expecting reboot configured "/noreboot" in the configuration.

There are a lot of materials about Kubernetes on official site and I encourage you to check it out:

• Kubernetes.io

I divided this answer on parts:

• CNI
• Troubleshooting

What is CNI?

CNI (Container Network Interface), a Cloud Native Computing Foundation project, consists of a specification and libraries for writing plugins to configure network interfaces in Linux containers, along with a number of supported plugins. CNI concerns itself only with network connectivity of containers and removing allocated resources when the container is deleted. Because of this focus, CNI has a wide range of support and the specification is simple to implement.

-- Github.com: Containernetworking: CNI

Your CNI plugin in simple terms is responsible for pod's networking inside your cluster.

There are multiple CNI plugins like:

• Flannel
• Calico
• Multus
• Weavenet

What I mean about that, you don't need to use Flannel. You can use other plugin like Calico. The major consideration is that they are different from each other and you should pick option best for your use case (support for some feature for example).

There are a lot of materials/resources on this topic. Please take a look at some of them:

• Youtube.com: Kubernetes and the CNI: Where We Are and What's Next - Casey Callendrello, CoreOS
• Youtube.com: Container Network Interface (CNI) Explained in 7 Minutes
• Kubernetes.io: Docs: Concepts: Cluster administration: Networking

As for:

If Flannel is difficult to setup for mixed mode, can we use other network which can work?

If you mean mixed mode by using nodes that are Windows and Linux machines, I would stick to guides that are already written like one you mentioned: Kubernetes.io: Adding Windows nodes

As for:

If we decide to go only and only RHEL nodes, what is the best and easiest network plugin I can install without going through lot of issues?

The best way to choose CNI plugin would entail looking for solution fitting your needs the most. You can follow this link for an overview:

• Kubernetes.io: Docs: Concepts: Cluster administration: Networking

Also you can look here (Please have in mind that this article is from 2018 and could be outdated):

• Itnext.io: Benchmark results of Kubernetes network plugin cni over 10gbit's network

when I go to my RHEL worker node, I see that k8s_install-cni_kube-flannel-ds-amd64-f4mtp_kube-system container is exited as seen below:

Your k8s_install-cni_kube-flannel-ds-amd64-f4mtp_kube-system container exited with status 0 which should indicate correct provisioning.

You can check the logs of flannel pods by invoking below command:

• kubectl logs POD_NAME

You can also refer to official documentation of Flannel: Github.com: Flannel: Troubleshooting

As I said in the comment:

To check if your CNI is working you can spawn 2 pods on 2 different nodes and try make a connection between them (like ping them).

Steps:

• Spawn pods
• Check their IP addresses
• Exec into pods
• Ping

Below is example deployment definition that will spawn ubuntu pods. They will be used to check if pods have communication between nodes:

Just make the modification on the file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf