94 lines
3.7 KiB
Markdown
94 lines
3.7 KiB
Markdown
# Generating Bash Completions For Your cobra.Command
|
|
|
|
Please refer to [Shell Completions](shell_completions.md) for details.
|
|
|
|
## Bash legacy dynamic completions
|
|
|
|
For backward compatibility, Cobra still supports its legacy dynamic completion solution (described below). Unlike the `ValidArgsFunction` solution, the legacy solution will only work for Bash shell-completion and not for other shells. This legacy solution can be used along-side `ValidArgsFunction` and `RegisterFlagCompletionFunc()`, as long as both solutions are not used for the same command. This provides a path to gradually migrate from the legacy solution to the new solution.
|
|
|
|
**Note**: Cobra's default `completion` command uses bash completion V2. If you are currently using Cobra's legacy dynamic completion solution, you should not use the default `completion` command but continue using your own.
|
|
|
|
The legacy solution allows you to inject bash functions into the bash completion script. Those bash functions are responsible for providing the completion choices for your own completions.
|
|
|
|
Some code that works in kubernetes:
|
|
|
|
```bash
|
|
const (
|
|
bash_completion_func = `__kubectl_parse_get()
|
|
{
|
|
local kubectl_output out
|
|
if kubectl_output=$(kubectl get --no-headers "$1" 2>/dev/null); then
|
|
out=($(echo "${kubectl_output}" | awk '{print $1}'))
|
|
COMPREPLY=( $( compgen -W "${out[*]}" -- "$cur" ) )
|
|
fi
|
|
}
|
|
|
|
__kubectl_get_resource()
|
|
{
|
|
if [[ ${#nouns[@]} -eq 0 ]]; then
|
|
return 1
|
|
fi
|
|
__kubectl_parse_get ${nouns[${#nouns[@]} -1]}
|
|
if [[ $? -eq 0 ]]; then
|
|
return 0
|
|
fi
|
|
}
|
|
|
|
__kubectl_custom_func() {
|
|
case ${last_command} in
|
|
kubectl_get | kubectl_describe | kubectl_delete | kubectl_stop)
|
|
__kubectl_get_resource
|
|
return
|
|
;;
|
|
*)
|
|
;;
|
|
esac
|
|
}
|
|
`)
|
|
```
|
|
|
|
And then I set that in my command definition:
|
|
|
|
```go
|
|
cmds := &cobra.Command{
|
|
Use: "kubectl",
|
|
Short: "kubectl controls the Kubernetes cluster manager",
|
|
Long: `kubectl controls the Kubernetes cluster manager.
|
|
|
|
Find more information at https://github.com/GoogleCloudPlatform/kubernetes.`,
|
|
Run: runHelp,
|
|
BashCompletionFunction: bash_completion_func,
|
|
}
|
|
```
|
|
|
|
The `BashCompletionFunction` option is really only valid/useful on the root command. Doing the above will cause `__kubectl_custom_func()` (`__<command-use>_custom_func()`) to be called when the built in processor was unable to find a solution. In the case of kubernetes a valid command might look something like `kubectl get pod [mypod]`. If you type `kubectl get pod [tab][tab]` the `__kubectl_customc_func()` will run because the cobra.Command only understood "kubectl" and "get." `__kubectl_custom_func()` will see that the cobra.Command is "kubectl_get" and will thus call another helper `__kubectl_get_resource()`. `__kubectl_get_resource` will look at the 'nouns' collected. In our example the only noun will be `pod`. So it will call `__kubectl_parse_get pod`. `__kubectl_parse_get` will actually call out to kubernetes and get any pods. It will then set `COMPREPLY` to valid pods!
|
|
|
|
Similarly, for flags:
|
|
|
|
```go
|
|
annotation := make(map[string][]string)
|
|
annotation[cobra.BashCompCustom] = []string{"__kubectl_get_namespaces"}
|
|
|
|
flag := &pflag.Flag{
|
|
Name: "namespace",
|
|
Usage: usage,
|
|
Annotations: annotation,
|
|
}
|
|
cmd.Flags().AddFlag(flag)
|
|
```
|
|
|
|
In addition add the `__kubectl_get_namespaces` implementation in the `BashCompletionFunction`
|
|
value, e.g.:
|
|
|
|
```bash
|
|
__kubectl_get_namespaces()
|
|
{
|
|
local template
|
|
template="{{ range .items }}{{ .metadata.name }} {{ end }}"
|
|
local kubectl_out
|
|
if kubectl_out=$(kubectl get -o template --template="${template}" namespace 2>/dev/null); then
|
|
COMPREPLY=( $( compgen -W "${kubectl_out}[*]" -- "$cur" ) )
|
|
fi
|
|
}
|
|
```
|