Explore hcsshim for connectivity between windows containers on windows

1. This repo walks through hnsshim (hcn) to play with connectivity between windows containers on windows 2022 preview. This page are compiled based on resources from NPM and hcsshim teams.

Prerequisite for setup win 2022

1. Git
2. Golang
3. vscode - go extension

Set up docker on win 2022

1. Get started: Prep Windows for containers

Play with HNS to control networks

1. Create two dockers

• One for a server
  • Many windows container examples

# This dockerfile utilizes components licensed by their respective owners/authors.
# Prior to utilizing this file or resulting images please review the respective licenses at: http://nginx.org/LICENSE
FROM mcr.microsoft.com/windows/server/insider:10.0.20344.1
LABEL Description="Nginx" Vendor="Nginx" Version="1.0.13"
RUN powershell -Command \
        $ErrorActionPreference = 'Stop'; \
        Invoke-WebRequest -Method Get -Uri http://nginx.org/download/nginx-1.9.13.zip -OutFile c:\nginx-1.9.13.zip ; \
        Expand-Archive -Path c:\nginx-1.9.13.zip -DestinationPath c:\ ; \
        Remove-Item c:\nginx-1.9.13.zip -Force

WORKDIR /nginx-1.9.13
CMD ["/nginx-1.9.13/nginx.exe"]

• Build docker and run it

docker build -t nginx -f Dockerfile .
docker run --name nginx -d nginx 

• One for a client - to keep running docker container

docker run -d --name client  mcr.microsoft.com/windows/server/insider:10.0.20344.1 ping -t localhost

• Test connectivity between docker

docker exec -it client cmd.exe
# you can access to console of nginx docker and type ipconfig
> powershell
> curl.exe <nginx ip address>

• Print current endpoint status
  • nginx endpoint id : edffc876-3051-46ec-80b3-820dda20aa14
  • client endpoint id : c047102f-2bb1-4f64-8f30-9ede02f464f1

# on powershell
PS C:\Users\azure> Get-HnsEndpoint
ID                 : edffc876-3051-46ec-80b3-820dda20aa14
ID                 : c047102f-2bb1-4f64-8f30-9ede02f464f1

3. Run simple go example to use hns to control network policy. It needs some manual option to change the code. Please check main.go

go build -o hns main.go

• Output comparison after blocking and allowing traffic

* Output from `Get-HnsEndpoint` after blocking and allowing traffic
  - nginx endpoint id : `edffc876-3051-46ec-80b3-820dda20aa14`
  - client endpoint id : `c047102f-2bb1-4f64-8f30-9ede02f464f1`
```shell
# After blocking traffic
PS C:\k\debug> Get-HnsEndpoint
ID                 : edffc876-3051-46ec-80b3-820dda20aa14
Policies           : {@{Action=Block; Direction=In; LocalAddresses=172.19.6.74; LocalPorts=80; Priority=100; Protocols=6; Scope=0; Type=ACL}, @{Action=Block; Direction=Out;
                     Priority=100; Protocols=6; Scope=0; Type=ACL}, @{Action=Block; Direction=In; LocalAddresses=172.19.6.74; LocalPorts=80; Priority=100; Protocols=6; Scope=0;
                     Type=ACL}, @{Action=Block; Direction=Out; Priority=100; Protocols=6; Scope=0; Type=ACL}}

ID                 : c047102f-2bb1-4f64-8f30-9ede02f464f1

# After allowing traffic
PS C:\k\debug> Get-HnsEndpoint
ID                 : edffc876-3051-46ec-80b3-820dda20aa14
Policies           : {@{Action=Allow; Direction=In; LocalAddresses=172.19.6.74; LocalPorts=80; Priority=100; Protocols=6; Scope=0; Type=ACL}, @{Action=Allow; Direction=Out;
                     Priority=100; Protocols=6; Scope=0; Type=ACL}}

ID                 : c047102f-2bb1-4f64-8f30-9ede02f464f1

Tested windows docker images

1. Compatible containers
* [Announcing a New Windows Server Container Image Preview](https://techcommunity.microsoft.com/t5/containers/announcing-a-new-windows-server-container-image-preview/ba-p/2304897?ranMID=24542&ranEAID=je6NUbpObpQ&ranSiteID=je6NUbpObpQ-7G741ImEBgESfTcCBeFawQ&epi=je6NUbpObpQ-7G741ImEBgESfTcCBeFawQ&irgwc=1&OCID=AID2200057_aff_7593_1243925&tduid=(ir__ms1mv9qee9kfqib1cydiwswhr22xr3pgbcmzyur300)(7593)(1243925)(je6NUbpObpQ-7G741ImEBgESfTcCBeFawQ)() irclickid=_ms1mv9qee9kfqib1cydiwswhr22xr3pgbcmzyur300)
* [Nano Server Insider](https://hub.docker.com/_/microsoft-windows-nanoserver-insider)
* [Windows Server Insider](https://hub.docker.com/_/microsoft-windows-server-insider)
* [Windows Server Core Insider](https://hub.docker.com/_/microsoft-windows-servercore-insider)