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main.go
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main.go
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// Copyright © 2018 The Knative Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"fmt"
"math/rand"
"os"
"regexp"
"strings"
"time"
"github.com/pkg/errors"
"github.com/spf13/cobra"
"knative.dev/client/pkg/kn/config"
"knative.dev/client/pkg/kn/plugin"
"knative.dev/client/pkg/kn/root"
)
func init() {
rand.Seed(time.Now().UnixNano())
}
func main() {
err := run(os.Args[1:])
if err != nil && len(os.Args) > 1 {
printError(err)
// This is the only point from where to exit when an error occurs
os.Exit(1)
}
}
// runError is used when during the execution of a command/plugin an error occurs and
// so no extra usage message should be shown.
type runError struct {
err error
}
// Error implements the error() interface
func (e *runError) Error() string {
return e.err.Error()
}
// Run the main program. Args are the args as given on the command line (excluding the program name itself)
func run(args []string) error {
// Parse config & plugin flags early to read in configuration file
// and bind to viper. After that you can access all configuration and
// global options via methods on config.GlobalConfig
err := config.BootstrapConfig()
if err != nil {
return err
}
// Strip of all flags to get the non-flag commands only
commands, err := stripFlags(args)
if err != nil {
return err
}
// Find plugin with the commands arguments
pluginManager := plugin.NewManager(config.GlobalConfig.PluginsDir(), config.GlobalConfig.LookupPluginsInPath())
plugin, err := pluginManager.FindPlugin(commands)
if err != nil {
return err
}
// Create kn root command and all sub-commands
rootCmd, err := root.NewRootCommand(pluginManager.HelpTemplateFuncs())
if err != nil {
return err
}
if plugin != nil {
// Validate & Execute plugin
err = validatePlugin(rootCmd, plugin)
if err != nil {
return err
}
err := plugin.Execute(argsWithoutCommands(args, plugin.CommandParts()))
if err != nil {
return &runError{err: err}
}
return nil
} else {
// Validate args for root command
err = validateRootCommand(rootCmd)
if err != nil {
return err
}
// Execute kn root command, args are taken from os.Args directly
return rootCmd.Execute()
}
}
// Get only the args provided but no options. The extraction
// process is a bit tricky as Cobra doesn't provide such
// functionality out of the box
func stripFlags(args []string) ([]string, error) {
// Store all command
commandsFound := &[]string{}
// Use a canary command that allows all options and only extracts
// commands. Doesn't work with arbitrary boolean flags but is good enough
// for us here
extractCommand := cobra.Command{
Run: func(cmd *cobra.Command, args []string) {
for _, arg := range args {
*commandsFound = append(*commandsFound, arg)
}
},
SilenceErrors: true,
SilenceUsage: true,
}
// No help and usage functions to prin
extractCommand.SetHelpFunc(func(*cobra.Command, []string) {})
extractCommand.SetUsageFunc(func(*cobra.Command) error { return nil })
// Filter out --help and -h options to avoid special treatment which we don't
// need here
extractCommand.SetArgs(filterHelpOptions(args))
// Adding all global flags here
config.AddBootstrapFlags(extractCommand.Flags())
// Allow all options
extractCommand.FParseErrWhitelist = cobra.FParseErrWhitelist{UnknownFlags: true}
// Execute to get to the command args
err := extractCommand.Execute()
if err != nil {
return nil, err
}
return *commandsFound, nil
}
// Strip all plugin commands before calling out to the plugin
func argsWithoutCommands(cmdArgs []string, pluginCommandsParts []string) []string {
var ret []string
for _, arg := range cmdArgs {
if len(pluginCommandsParts) > 0 && pluginCommandsParts[0] == arg {
pluginCommandsParts = pluginCommandsParts[1:]
continue
}
ret = append(ret, arg)
}
return ret
}
// Remove all help options
func filterHelpOptions(args []string) []string {
var ret []string
for _, arg := range args {
if arg != "-h" && arg != "--help" {
ret = append(ret, arg)
}
}
return ret
}
// Check if the plugin collides with any command specified in the root command
func validatePlugin(root *cobra.Command, plugin plugin.Plugin) error {
// Check if a given plugin can be identified as a command
cmd, args, err := root.Find(plugin.CommandParts())
if err == nil {
if !cmd.HasSubCommands() || // a leaf command can't be overridden
cmd.HasSubCommands() && len(args) == 0 { // a group can't be overridden either
return errors.Errorf("plugin %s is overriding built-in command '%s' which is not allowed", plugin.Path(), strings.Join(plugin.CommandParts(), " "))
}
}
return nil
}
// Check whether an unknown sub-command is addressed and return an error if this is the case
// Needs to be called after the plugin has been extracted (as a plugin name can also lead to
// an unknown sub command error otherwise)
func validateRootCommand(cmd *cobra.Command) error {
foundCmd, innerArgs, err := cmd.Find(os.Args[1:])
if err == nil && foundCmd.HasSubCommands() && len(innerArgs) > 0 {
argsWithoutFlags, err := stripFlags(innerArgs)
if len(argsWithoutFlags) > 0 || err != nil {
return errors.Errorf("unknown sub-command '%s' for '%s'. Available sub-commands: %s", innerArgs[0], foundCmd.CommandPath(), strings.Join(root.ExtractSubCommandNames(foundCmd.Commands()), ", "))
}
// If no args where given (only flags), then fall through to execute the command itself, which leads to
// a more appropriate error message
}
return nil
}
// printError prints out any given error
func printError(err error) {
fmt.Fprintf(os.Stderr, "Error: %s\n", cleanupErrorMessage(err.Error()))
var runError *runError
if !errors.As(err, &runError) {
// Print help hint only if its not a runError occurred when executing a command
fmt.Fprintf(os.Stderr, "Run '%s --help' for usage\n", extractCommandPathFromErrorMessage(err.Error(), os.Args[0]))
}
}
// extractCommandPathFromErrorMessage tries to extract the command name from an error message
// by checking a pattern like 'kn service' in the error message. If not found, return the
// base command name.
func extractCommandPathFromErrorMessage(errorMsg string, arg0 string) string {
extractPattern := regexp.MustCompile(fmt.Sprintf("'(%s\\s.+?)'", arg0))
command := extractPattern.FindSubmatch([]byte(errorMsg))
if command != nil {
return string(command[1])
}
return arg0
}
// cleanupErrorMessage remove any redundance content of an error message
func cleanupErrorMessage(msg string) string {
regexp := regexp.MustCompile("(?i)^error:\\s*")
return string(regexp.ReplaceAll([]byte(msg), []byte("")))
}