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diff --git a/vendor/github.com/spf13/cobra/bash_completions.md b/vendor/github.com/spf13/cobra/bash_completions.md new file mode 100644 index 000000000..e79d4769d --- /dev/null +++ b/vendor/github.com/spf13/cobra/bash_completions.md @@ -0,0 +1,221 @@ +# 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" + + "k8s.io/kubernetes/pkg/kubectl/cmd" + "k8s.io/kubernetes/pkg/kubectl/cmd/util" +) + +func main() { + kubectl := cmd.NewKubectlCommand(util.NewFactory(nil), 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. + +# Specify custom flag completion + +Similar to the filename completion and filtering using cobra.BashCompFilenameExt, you can specify +a custom flag completion function with cobra.BashCompCustom: + +```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 `__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}[*]" -- "$cur" ) ) + fi +} +``` +# Using bash aliases for commands + +You can also configure the `bash aliases` for the commands and they will also support completions. + +```bash +alias aliasname=origcommand +complete -o default -F __start_origcommand aliasname + +# and now when you run `aliasname` completion will make +# suggestions as it did for `origcommand`. + +$) aliasname <tab><tab> +completion firstcommand secondcommand +``` |