util: support load Colon-separated KUBECONFIG

[morlay]

fix #437 #760

[morlay]

Should we still need this?

github.com/docker/cli/cli/context/kubernetes not provide a way to load Colon-separated KUBECONFIG
now changes could support all KUBECONFIG, and will not execute this line any more

[Dentrax]

$ echo $KUBECONFIG
:/Users/furkan.turkal/.kube/config:/Users/furkan.turkal/.kube/foo:/Users/furkan.turkal/.kube/bar:/Users/furkan.turkal/.kube/baz

This returns me the following error for this commit:

Error: could not read kubeconfig: stat : no such file or directory

[morlay]

@Dentrax

this pr should fix it.
the new kubeconfig load follow kubectl did

[morlay]

why your kubeconfig value startswith :

[Dentrax]

why your kubeconfig value startswith :

🤷‍♂️I removed : prefix and still getting same error. 🤔

[morlay]

$ docker buildx create --name=kubeconfig --driver=kubernetes --driver-opt=namespace=gitlab
kubeconfig
$ docker buildx inspect kubeconfig                                                        
Name:   kubeconfig
Driver: kubernetes

Nodes:
Name:      kubeconfig0
Endpoint:  kubernetes:///kubeconfig?deployment=&kubeconfig=%2FUsers%2Fmorlay%2F.kube%2Fconfig--hw-dev.yaml%3A%2FUsers%2Fmorlay%2F.kube%2Fconfig--hw-infra.yaml%3A%2FUsers%2Fmorlay%2F.kube%2Fconfig--hw-sg.yaml%3A%2FUsers%2Fmorlay%2F.kube%2Fconfig--qc-hk.yaml
Status:    inactive
Platforms: 
$ docker buildx inspect kubeconfig --bootstrap
[+] Building 21.9s (1/1) FINISHED                                                                                                                                           
 => [internal] booting buildkit                                                                                                                                       21.8s
 => => waiting for 1 pods to be ready                                                                                                                                 21.5s
Name:   kubeconfig
Driver: kubernetes

Nodes:
Name:      kubeconfig0-787cbbd5d9-4fpf7
Endpoint:  
Status:    running
Platforms: linux/amd64, linux/arm64, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/mips64le, linux/mips64, linux/arm/v7, linux/arm/v6

Works well for me.

[tonistiigi]

Should we remove empty files?

[morlay]

Should we remove empty files?

kubectl didn't, so i don't think we should add file exists checking.

For me, my KUBECONFIG set like this to make sure files exists.

export KUBECONFIG=$(echo $(ls ~/.kube/config--*.yaml) | sed 's/ /:/g')

[Dentrax]

@morlay Just applied your pull patch in my own fork and it seems working now but:

$ kubectl config current-context
kind-cluster-api-test

$ go run cmd/buildx/main.go create --name=kubeconfig --driver=kubernetes --driver-opt=namespace=gitlab
kubeconfig

$ go run cmd/buildx/main.go inspect kubeconfig
Name:   kubeconfig
Driver: kubernetes

Nodes:
Name:      kubeconfig0-787cbbd5d9-d2d9w
Endpoint:
Status:    running
Platforms: linux/amd64, linux/386

But getting the following issue and not sure if it's related to this, any ideas?

$ cat ~/.docker/buildx/instances/kubeconfig
{"Name":"kubeconfig","Driver":"kubernetes","Nodes":[{"Name":"kubeconfig0","Endpoint":"kubernetes:///kubeconfig?deployment=\u0026kubeconfig=%3A%2FUsers%2Ffurkan.turkal%2F.kube%2Fconfig%3A%2FUsers%2Ffurkan.turkal%2F.kube%2Ffoo%3A%2FUsers%2Ffurkan.turkal%2F.kube%2Fbar%3A%2FUsers%2Ffurkan.turkal%2F.kube%2Fbaz%3A%2FUsers%2Ffurkan.turkal%2Fauth%2Fk8s-auto%2FS_PLATFORM_P1_6PLATFORM_MOON","Platforms":null,"Flags":null,"ConfigFile":"","DriverOpts":{"namespace":"gitlab"}}],"Dynamic":false}

$ kubectl config get-contexts
CURRENT   NAME                                            CLUSTER                        AUTHINFO           NAMESPACE
*         kubernetes-admin@s-platform-p1-6platform-moon   s-platform-p1-6platform-moon   kubernetes-admin

$ kubectl cluster-info
Kubernetes control plane is running at ...
Metrics-server is running at ...
...

$ kubectl get pods -n gitlab
NAME                           READY   STATUS    RESTARTS   AGE
kubeconfig0-787cbbd5d9-d2d9w   1/1     Running   0          27m

$ ./buildx build -t test:simple-golang-app -f Dockerfile .
[+] Building 0.0s (0/0)
Error: no valid drivers found: cannot determine Kubernetes namespace, specify manually: invalid configuration: [context was not found for specified context: kubernetes-admin@s-platform-p1-6platform-moon, cluster has no server defined]

[morlay]

@Dentrax

Why your kubectl config current-context not match kubectl config get-contexts ?

This * should point like

$ kubectl config current-context
hw-dev
$ kubectl config get-contexts
CURRENT   NAME       CLUSTER    AUTHINFO   NAMESPACE
*         hw-dev     hw-dev     user1      
          hw-infra   hw-infra   hw-infra   
          hw-sg      hw-sg      hw-sg      
          qc-hk      default    default  

[tonistiigi]

@AkihiroSuda still lgty?