Add bash completion custom functions

These functions call out to kubectl to get information about running
resources.  They give us completions which are kubernetes aware and thus
obviously better than just cobra subcommands and flags.

contrib/completions/bash/kubectl

@@ -149,6 +149,73 @@ __handle_word()
     __handle_word
 }
 
+# call kubectl get $1,
+# use the first column in compgen
+# we could use templates, but then would need a template per resource
+__kubectl_parse_get()
+{
+    local kubectl_output out
+    if kubectl_output=$(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
+}
+
+# $1 is the name of the pod we want to get the list of containers inside
+__kubectl_get_containers()
+{
+    local template
+    template="{{ range .desiredState.manifest.containers  }}{{ .name }} {{ end }}"
+    __debug ${FUNCNAME} "nouns are ${nouns[@]}"
+
+    local len="${#nouns[@]}"
+    if [[ ${len} -ne 1 ]]; then
+        return
+    fi
+    local last=${nouns[${len} -1]}
+    local kubectl_out
+    if kubectl_out=$(kubectl get -o template --template="${template}" pods "${last}" 2>/dev/null); then
+        COMPREPLY=( $( compgen -W "${kubectl_out[*]}" -- "$cur" ) )
+    fi
+}
+
+# Require both a pod and a container to be specified
+__kubectl_require_pod_and_container()
+{
+    if [[ ${#nouns[@]} -eq 0 ]]; then
+        __kubectl_parse_get pods
+        return 0
+    fi;
+    __kubectl_get_containers
+    return 0
+}
+
+__custom_func() {
+    case ${last_command} in
+        kubectl_get | kubectl_describe | kubectl_delete | kubectl_stop)
+	    __kubectl_get_resource
+            return
+            ;;
+	kubectl_log)
+	    __kubectl_require_pod_and_container
+	    return
+	    ;;
+        *)
+            ;;
+    esac
+}
+
 _kubectl_get()
 {
     last_command="kubectl_get"

pkg/kubectl/cmd/cmd.go

@@ -26,6 +26,76 @@ import (
 	"github.com/spf13/cobra"
 )
 
+const (
+	bash_completion_func = `# call kubectl get $1,
+# use the first column in compgen
+# we could use templates, but then would need a template per resource
+__kubectl_parse_get()
+{
+    local kubectl_output out
+    if kubectl_output=$(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
+}
+
+# $1 is the name of the pod we want to get the list of containers inside
+__kubectl_get_containers()
+{
+    local template
+    template="{{ range .desiredState.manifest.containers  }}{{ .name }} {{ end }}"
+    __debug ${FUNCNAME} "nouns are ${nouns[@]}"
+
+    local len="${#nouns[@]}"
+    if [[ ${len} -ne 1 ]]; then
+        return
+    fi
+    local last=${nouns[${len} -1]}
+    local kubectl_out
+    if kubectl_out=$(kubectl get -o template --template="${template}" pods "${last}" 2>/dev/null); then
+        COMPREPLY=( $( compgen -W "${kubectl_out[*]}" -- "$cur" ) )
+    fi
+}
+
+# Require both a pod and a container to be specified
+__kubectl_require_pod_and_container()
+{
+    if [[ ${#nouns[@]} -eq 0 ]]; then
+        __kubectl_parse_get pods
+        return 0
+    fi;
+    __kubectl_get_containers
+    return 0
+}
+
+__custom_func() {
+    case ${last_command} in
+        kubectl_get | kubectl_describe | kubectl_delete | kubectl_stop)
+	    __kubectl_get_resource
+            return
+            ;;
+	kubectl_log)
+	    __kubectl_require_pod_and_container
+	    return
+	    ;;
+        *)
+            ;;
+    esac
+}
+`
+)
+
 // NewKubectlCommand creates the `kubectl` command and its nested children.
 func NewKubectlCommand(f *cmdutil.Factory, in io.Reader, out, err io.Writer) *cobra.Command {
 	// Parent command to which all subcommands are added.
@@ -36,6 +106,7 @@ func NewKubectlCommand(f *cmdutil.Factory, in io.Reader, out, err io.Writer) *co
 
 Find more information at https://github.com/GoogleCloudPlatform/kubernetes.`,
 		Run: runHelp,
+		BashCompletionFunction: bash_completion_func,
 	}
 
 	f.BindFlags(cmds.PersistentFlags())