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94 lines
3.7 KiB
Bash
94 lines
3.7 KiB
Bash
2 years ago
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# Generating Bash Completions For Your cobra.Command
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Please refer to [Shell Completions](shell_completions.md) for details.
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## Bash legacy dynamic completions
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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.
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**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.
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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.
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Some code that works in kubernetes:
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```bash
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const (
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bash_completion_func = `__kubectl_parse_get()
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{
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local kubectl_output out
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if kubectl_output=$(kubectl get --no-headers "$1" 2>/dev/null); then
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out=($(echo "${kubectl_output}" | awk '{print $1}'))
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COMPREPLY=( $( compgen -W "${out[*]}" -- "$cur" ) )
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fi
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}
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__kubectl_get_resource()
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{
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if [[ ${#nouns[@]} -eq 0 ]]; then
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return 1
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fi
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__kubectl_parse_get ${nouns[${#nouns[@]} -1]}
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if [[ $? -eq 0 ]]; then
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return 0
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fi
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}
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__kubectl_custom_func() {
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case ${last_command} in
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kubectl_get | kubectl_describe | kubectl_delete | kubectl_stop)
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__kubectl_get_resource
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return
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;;
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*)
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;;
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esac
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}
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`)
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```
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And then I set that in my command definition:
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```go
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cmds := &cobra.Command{
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Use: "kubectl",
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Short: "kubectl controls the Kubernetes cluster manager",
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Long: `kubectl controls the Kubernetes cluster manager.
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Find more information at https://github.com/GoogleCloudPlatform/kubernetes.`,
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Run: runHelp,
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BashCompletionFunction: bash_completion_func,
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}
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```
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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!
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Similarly, for flags:
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```go
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annotation := make(map[string][]string)
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annotation[cobra.BashCompCustom] = []string{"__kubectl_get_namespaces"}
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flag := &pflag.Flag{
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Name: "namespace",
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Usage: usage,
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Annotations: annotation,
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}
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cmd.Flags().AddFlag(flag)
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```
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In addition add the `__kubectl_get_namespaces` implementation in the `BashCompletionFunction`
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value, e.g.:
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```bash
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__kubectl_get_namespaces()
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{
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local template
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template="{{ range .items }}{{ .metadata.name }} {{ end }}"
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local kubectl_out
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if kubectl_out=$(kubectl get -o template --template="${template}" namespace 2>/dev/null); then
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COMPREPLY=( $( compgen -W "${kubectl_out}[*]" -- "$cur" ) )
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fi
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}
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```
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