+++ /dev/null
-# Generating Bash Completions For Your Own cobra.Command
-
-Generating bash completions from a cobra command is incredibly easy. An actual program which does so for the kubernetes kubectl binary is as follows:
-
-```go
-package main
-
-import (
- "io/ioutil"
- "os"
-
- "github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl/cmd"
-)
-
-func main() {
- kubectl := cmd.NewFactory(nil).NewKubectlCommand(os.Stdin, ioutil.Discard, ioutil.Discard)
- kubectl.GenBashCompletionFile("out.sh")
-}
-```
-
-`out.sh` will get you completions of subcommands and flags. Copy it to `/etc/bash_completion.d/` as described [here](https://debian-administration.org/article/316/An_introduction_to_bash_completion_part_1) and reset your terminal to use autocompletion. If you make additional annotations to your code, you can get even more intelligent and flexible behavior.
-
-## Creating your own custom functions
-
-Some more actual 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
-}
-
-__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 `__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 `__customc_func()` will run because the cobra.Command only understood "kubectl" and "get." `__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!
-
-## Have the completions code complete your 'nouns'
-
-In the above example "pod" was assumed to already be typed. But if you want `kubectl get [tab][tab]` to show a list of valid "nouns" you have to set them. Simplified code from `kubectl get` looks like:
-
-```go
-validArgs []string = { "pod", "node", "service", "replicationcontroller" }
-
-cmd := &cobra.Command{
- Use: "get [(-o|--output=)json|yaml|template|...] (RESOURCE [NAME] | RESOURCE/NAME ...)",
- Short: "Display one or many resources",
- Long: get_long,
- Example: get_example,
- Run: func(cmd *cobra.Command, args []string) {
- err := RunGet(f, out, cmd, args)
- util.CheckErr(err)
- },
- ValidArgs: validArgs,
-}
-```
-
-Notice we put the "ValidArgs" on the "get" subcommand. Doing so will give results like
-
-```bash
-# kubectl get [tab][tab]
-node pod replicationcontroller service
-```
-
-## Plural form and shortcuts for nouns
-
-If your nouns have a number of aliases, you can define them alongside `ValidArgs` using `ArgAliases`:
-
-```go
-argAliases []string = { "pods", "nodes", "services", "svc", "replicationcontrollers", "rc" }
-
-cmd := &cobra.Command{
- ...
- ValidArgs: validArgs,
- ArgAliases: argAliases
-}
-```
-
-The aliases are not shown to the user on tab completion, but they are accepted as valid nouns by
-the completion algorithm if entered manually, e.g. in:
-
-```bash
-# kubectl get rc [tab][tab]
-backend frontend database
-```
-
-Note that without declaring `rc` as an alias, the completion algorithm would show the list of nouns
-in this example again instead of the replication controllers.
-
-## Mark flags as required
-
-Most of the time completions will only show subcommands. But if a flag is required to make a subcommand work, you probably want it to show up when the user types [tab][tab]. Marking a flag as 'Required' is incredibly easy.
-
-```go
-cmd.MarkFlagRequired("pod")
-cmd.MarkFlagRequired("container")
-```
-
-and you'll get something like
-
-```bash
-# kubectl exec [tab][tab][tab]
--c --container= -p --pod=
-```
-
-# Specify valid filename extensions for flags that take a filename
-
-In this example we use --filename= and expect to get a json or yaml file as the argument. To make this easier we annotate the --filename flag with valid filename extensions.
-
-```go
- annotations := []string{"json", "yaml", "yml"}
- annotation := make(map[string][]string)
- annotation[cobra.BashCompFilenameExt] = annotations
-
- flag := &pflag.Flag{
- Name: "filename",
- Shorthand: "f",
- Usage: usage,
- Value: value,
- DefValue: value.String(),
- Annotations: annotation,
- }
- cmd.Flags().AddFlag(flag)
-```
-
-Now when you run a command with this filename flag you'll get something like
-
-```bash
-# kubectl create -f
-test/ example/ rpmbuild/
-hello.yml test.json
-```
-
-So while there are many other files in the CWD it only shows me subdirs and those with valid extensions.
-
-# Specifiy custom flag completion
-
-Similar to the filename completion and filtering using cobra.BashCompFilenameExt, you can specifiy
-a custom flag completion function with cobra.BashCompCustom:
-
-```go
- annotation := make(map[string][]string)
- annotation[cobra.BashCompFilenameExt] = []string{"__kubectl_get_namespaces"}
-
- flag := &pflag.Flag{
- Name: "namespace",
- Usage: usage,
- Annotations: annotation,
- }
- cmd.Flags().AddFlag(flag)
-```
-
-In addition add the `__handle_namespace_flag` 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
-}
-```
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