Tech Corner: September 2021

Monday, September 13, 2021

How to fix "HTTP Error 404.0 - Not Found" in Kubernetes ingress-nginx services?

i had setup the kubernetes Ingress with ingress-nginx with the following code, in my local machine,

which will direct the traffic to the backend service in kubernetes

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-srv
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/use-regex: "true"
spec:
  rules:
    - host: acme.com
      http:
        paths:
          - path: /api/platforms
            pathType: Prefix
            backend:
              service:
                name: platformservice-clusterip-srv
                port:
                  number: 80
          - path: /api/c/platforms
            pathType: Prefix
            backend:
              service:
                name: commandservice-clusterip-srv
                port:
                  number: 80

after the setup is complete. i try to browse to the platform service web api which is hosted in the backend server.

http://acme.com/api/platforms/ but the error comes up immediately, which indicated that

The directory or file specified does not exist on the Web server.

since the directory was not hosted in the IIS, it had been deployed to the pods in the kuberentes

As we manipulate the kubernetes in the local environment, we can check what process is using the port 80

C:\code\dotnet-microservices\k8s>netstat -ano | findstr ":80" | findstr "LISTENING"

TCP 0.0.0.0:80 0.0.0.0:0 LISTENING 4

TCP 0.0.0.0:8081 0.0.0.0:0 LISTENING 4

TCP [::]:80 [::]:0 LISTENING 4

TCP [::]:8081 [::]:0 LISTENING 4

the PID 4 represnet that the port 80 had been assigned to IIS local host. we should stop the World Wide Web Publishing Service, in order to release the port 80 for Kubernetes services.

after I stop the World Wide Web Publishing Service, the we can see that port 80 had been assigned to different processes.

C:\code\dotnet-microservices\k8s>netstat -ano | findstr ":80" | findstr "LISTENING"

TCP 0.0.0.0:80 0.0.0.0:0 LISTENING 3440

TCP [::]:80 [::]:0 LISTENING 3440

TCP [::1]:80 [::]:0 LISTENING 16096

Now we should be able to access the web api host in the kubernetes.

[{"id":1,"name":"dotnet","cost":"free","publisher":"Microsoft"},{"id":2,"name":"SQL Server Express","cost":"free","publisher":"Microsoft"},{"id":3,"name":"Kubernetes","cost":"free","publisher":"Cloud Native Computer Foundation"}]

Friday, September 10, 2021

how to fix "The SSL connection could not be established," in Web Api development with ASP.Net Core and .Net 5.0

I implemented two MicroServices in my local machine, I try to call one service from another with HttpClient. the error was shown as blew after the service call.

"cound not send data to commandservice with errror The SSL connection could not be established, see inner exception. System.Security.Authentication.AuthenticationException: The remote certificate is invalid because of errors in the certificate chain: UntrustedRoot at System.Net.Security.SslStream.SendAuthResetSignal(ProtocolToken message, ExceptionDispatchInfo exception)

at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Boolean receiveFirst, Byte[] reAuthenticationData, Boolean isApm)"

the error indicated that th SSL connection cannot be established due to certificate issue.

we can the use the following command to trust the self-singed certificate

dotnet dev-certs https --trust

for more information about this command you can check out the microsoft document website with the link below

https://docs.microsoft.com/en-us/dotnet/core/additional-tools/self-signed-certificates-guide

how to fix "Unable to connect to the server: dial tcp: lookup myaksclust-myresourcegroup-3f2c36-40a876eb.hcp.eastus.azmk8s.io: no such host" error?

when I try to check the version of Kubectl with kubectl version that is installed in my local desktop. i got the following error

"Unable to connect to the server: dial tcp: lookup myaksclust-myresourcegroup-3f2c36-40a876eb.hcp.eastus.azmk8s.io: no such host"

I check the kubectl configuration file with Kubectl config view

it shows with information below

apiVersion: v1

clusters:

- cluster:

certificate-authority-data: DATA+OMITTED

server: https://aks-cluste-aks-rg-3f2c36-a86fa58c.hcp.eastus.azmk8s.io:443

- cluster:

certificate-authority-data: DATA+OMITTED

server: https://kubernetes.docker.internal:6443

- cluster:

certificate-authority-data: DATA+OMITTED

server: https://kuar-clust-kuar-3f2c36-3176b3bf.hcp.eastus.azmk8s.io:443

- cluster:

certificate-authority: C:\Users\admin\.minikube\ca.crt

server: https://192.168.2.14:8443

- cluster:

certificate-authority-data: DATA+OMITTED

server: https://myaksclust-myresourcegroup-3f2c36-40a876eb.hcp.eastus.azmk8s.io:443

contexts:

- context:

cluster: aks-cluster

user: clusterUser_aks-rg_aks-cluster

- context:

cluster: docker-desktop

user: docker-desktop

- context:

cluster: kuar-cluster

user: clusterUser_kuar_kuar-cluster

- context:

cluster: minikube

user: minikube

- context:

cluster: myAKSCluster

user: clusterUser_myResourceGroup_myAKSCluster

current-context: myAKSCluster

kind: Config

preferences: {}

users:

- name: clusterUser_aks-rg_aks-cluster

user:

client-certificate-data: REDACTED

client-key-data: REDACTED

token: e4d785d3065d5697f03ac404ac27460f68b973b7185ea4697679077e39ff106437d3a7fe9c79f3be5cc84bbab6728e2d71bc010d0a6c6628bf05162958c122bb

- name: clusterUser_kuar_kuar-cluster

user:

client-certificate-data: REDACTED

client-key-data: REDACTED

token: afc713faf0d9c13f494711c3ab569d52c48c4ac1bef72f53329ab832247c0180f87a167d59c1a784ea0951bd11f043e8eb8aa6089caec2d9d71f61ea58d29b48

- name: clusterUser_myResourceGroup_myAKSCluster

user:

client-certificate-data: REDACTED

client-key-data: REDACTED

token: 2906f9edf219806a855010df4aa104f25eceea94ce748cf1b7813f3af93c531a60b853654b6bc0b24c448491ab3a5896ad36e0fa00d898507c44db7c69f8b283

- name: docker-desktop

user:

client-certificate-data: REDACTED

client-key-data: REDACTED

- name: minikube

user:

client-certificate: C:\Users\admin\.minikube\profiles\minikube\client.crt

client-key: C:\Users\admin\.minikube\profiles\minikube\client.key

we can see that the current-context is myAKSCluster, which is Azure Kubernetes Service. the error is sterm from that either authoriation token had been expired or the service instance had been removed from azure

Since we already know the root cause of the issue, we can change the kubectl context to the new AKS or the local docker-desktop.

we can follow the steps below

#to get all the context available in the kubectl configuration file

kubectl config get-contexts

CURRENT NAME CLUSTER AUTHINFO NAMESPACE

aks-cluster aks-cluster clusterUser_aks-rg_aks-cluster

docker-desktop docker-desktop docker-desktop

kuar-cluster kuar-cluster clusterUser_kuar_kuar-cluster

minikube minikube minikube

* myAKSCluster myAKSCluster clusterUser_myResourceGroup_myAKSCluster

#update the current context with local docker-desktop

kubectl config use-context docker-desktop

Monday, September 6, 2021

how to add a list of empty folders to github in windows environment?

When we setup the project structure in the development. the Github have prevent us to push all empty folder to the GitHub Repository in remote server. we can use gitkeep utility in the Macs and Linux environmen to create gitkeep for those blank folder. we cannot gitkeep in the Windows environment. but there is a work around. we can use the powershell scripts to loop through all subfolders under the current project folder and add .gitkeep file in each empty folder. then we can upload those folders to the server.

here is the code to be execute in the windows PowerShell ISE, you should copy it to your windows PowerSehll ISE and replace {Your Current Project Folder path} with your own folder path

Get-ChildItem '{Your Current Project Folder path}' -Recurse -Directory |

Where-Object {[System.IO.Directory]::GetFileSystemEntries($_.FullName).Count -eq 0} |

ForEach-Object { New-Item ($_.FullName + "\.gitkeep") -ItemType file}