feat: Longhorn toolbox CLI

[c3y1huang]

Which issue(s) this PR fixes:

Issue longhorn/longhorn#7927

What this PR does / why we need it:

See LEP.

Special notes for your reviewer:

None

Additional documentation or context

None

[derekbit]

nit: tried to undertand the longhornctl-local and longhornctl. The naming is a bit confusing. We can find better names later.

[derekbit]

./bin/longhornctl check preflight          
INFO[2024-07-09T15:17:34+08:00] Initializing preflight checker               
W0709 15:17:34.395440 3556587 client_config.go:659] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
W0709 15:17:34.395461 3556587 client_config.go:664] error creating inClusterConfig, falling back to default config: unable to load in-cluster configuration, KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT must be defined
ERRO[2024-07-09T15:17:34+08:00] Failed to initialize preflight checker: invalid configuration: no configuration has been provided, try setting KUBERNETES_MASTER environment variable 

Works after

# export KUBECONFIG=/root/.kube/config    
# ./bin/longhornctl check preflight   

Can we improve it by add an options --kubeconfig for longhornctl and longhornctl-local in the v1.8.0?

[c3y1huang]

./bin/longhornctl check preflight          
INFO[2024-07-09T15:17:34+08:00] Initializing preflight checker               
W0709 15:17:34.395440 3556587 client_config.go:659] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
W0709 15:17:34.395461 3556587 client_config.go:664] error creating inClusterConfig, falling back to default config: unable to load in-cluster configuration, KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT must be defined
ERRO[2024-07-09T15:17:34+08:00] Failed to initialize preflight checker: invalid configuration: no configuration has been provided, try setting KUBERNETES_MASTER environment variable 

Works after

# export KUBECONFIG=/root/.kube/config    
# ./bin/longhornctl check preflight   

Can we improve it by add an options --kubeconfig for longhornctl and longhornctl-local in the v1.8.0?

The option flag is available in the global options for the remote CLI; its not used in the local CLI. To see the menu, you can use this command:

./bin/longhornctl global-options

[derekbit]

./bin/longhornctl check preflight          
INFO[2024-07-09T15:17:34+08:00] Initializing preflight checker               
W0709 15:17:34.395440 3556587 client_config.go:659] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
W0709 15:17:34.395461 3556587 client_config.go:664] error creating inClusterConfig, falling back to default config: unable to load in-cluster configuration, KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT must be defined
ERRO[2024-07-09T15:17:34+08:00] Failed to initialize preflight checker: invalid configuration: no configuration has been provided, try setting KUBERNETES_MASTER environment variable 

Works after

# export KUBECONFIG=/root/.kube/config    
# ./bin/longhornctl check preflight   

Can we improve it by add an options --kubeconfig for longhornctl and longhornctl-local in the v1.8.0?

The option flag is available in the global options for the remote CLI; its not used in the local CLI. To see the menu, you can use this command:

./bin/longhornctl global-options

Thank you. found it!

[derekbit]

Except for the remote and local export functionality, other parts LGTM.

[derekbit]

LGTM