fn-serverless/cli/init.go

package main

/*
usage: fn init <name>

If there's a Dockerfile found, this will generate the basic file with just the image name. exit
It will then try to decipher the runtime based on the files in the current directory, if it can't figure it out, it will ask.
It will then take a best guess for what the entrypoint will be based on the language, it it can't guess, it will ask.

*/

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"

	"strings"

	"github.com/fnproject/fn/cli/langs"
	"github.com/funcy/functions_go/models"
	"github.com/urfave/cli"
)

var (
	fileExtToRuntime = map[string]string{
		".go":   "go",
		".js":   "node",
		".rb":   "ruby",
		".py":   "python",
		".php":  "php",
		".rs":   "rust",
		".cs":   "dotnet",
		".fs":   "dotnet",
		".java": "java",
	}

	fnInitRuntimes []string
)

func init() {
	for rt := range fileExtToRuntime {
		fnInitRuntimes = append(fnInitRuntimes, rt)
	}
}

type initFnCmd struct {
	name       string
	force      bool
	runtime    string
	entrypoint string
	cmd        string
	version    string
}

func initFlags(a *initFnCmd) []cli.Flag {
	fgs := []cli.Flag{
		cli.BoolFlag{
			Name:        "force",
			Usage:       "overwrite existing func.yaml",
			Destination: &a.force,
		},
		cli.StringFlag{
			Name:        "runtime",
			Usage:       "choose an existing runtime - " + strings.Join(fnInitRuntimes, ", "),
			Destination: &a.runtime,
		},
		cli.StringFlag{
			Name:        "entrypoint",
			Usage:       "entrypoint is the command to run to start this function - equivalent to Dockerfile ENTRYPOINT.",
			Destination: &a.entrypoint,
		},
		cli.StringFlag{
			Name:        "version",
			Usage:       "function version",
			Destination: &a.version,
			Value:       initialVersion,
		},
	}

	return append(fgs, routeFlags...)
}

func initFn() cli.Command {
	a := initFnCmd{}

	return cli.Command{
		Name:        "init",
		Usage:       "create a local func.yaml file",
		Description: "Creates a func.yaml file in the current directory.  ",
		ArgsUsage:   "<DOCKERHUB_USERNAME/FUNCTION_NAME>",
		Action:      a.init,
		Flags:       initFlags(&a),
	}
}

func (a *initFnCmd) init(c *cli.Context) error {

	rt := &models.Route{}
	routeWithFlags(c, rt)

	if !a.force {
		ff, err := loadFuncfile()
		if _, ok := err.(*notFoundError); !ok && err != nil {
			return err
		}
		if ff != nil {
			return errors.New("Function file already exists")
		}
	}

	runtimeSpecified := a.runtime != ""

	err := a.buildFuncFile(c)
	if err != nil {
		return err
	}

	if runtimeSpecified {
		err := a.generateBoilerplate()
		if err != nil {
			return err
		}
	}

	ff := &funcfile{
		*rt,
		a.name,
		a.version,
		&a.runtime,
		a.entrypoint,
		a.cmd,
		[]string{},
		[]fftest{},
	}

	_, path := appNamePath(ff.FullName())
	ff.Path = path

	if err := encodeFuncfileYAML("func.yaml", ff); err != nil {
		return err
	}

	fmt.Println("func.yaml created")
	return nil
}

func (a *initFnCmd) generateBoilerplate() error {
	helper := langs.GetLangHelper(a.runtime)
	if helper != nil && helper.HasBoilerplate() {
		if err := helper.GenerateBoilerplate(); err != nil {
			if err == langs.ErrBoilerplateExists {
				return nil
			}
			return err
		}
		fmt.Println("function boilerplate generated.")
	}
	return nil
}

func (a *initFnCmd) buildFuncFile(c *cli.Context) error {
	pwd, err := os.Getwd()
	if err != nil {
		return fmt.Errorf("error detecting current working directory: %s", err)
	}

	a.name = c.Args().First()
	if a.name == "" || strings.Contains(a.name, ":") {
		return errors.New("please specify a name for your function in the following format <DOCKERHUB_USERNAME>/<FUNCTION_NAME>.\nTry: fn init <DOCKERHUB_USERNAME>/<FUNCTION_NAME>")
	}

	if exists("Dockerfile") {
		fmt.Println("Dockerfile found. Let's use that to build...")
		return nil
	}

	var rt string
	if a.runtime == "" {
		rt, err = detectRuntime(pwd)
		if err != nil {
			return err
		}
		a.runtime = rt
		fmt.Printf("Found %v, assuming %v runtime.\n", rt, rt)
	} else {
		fmt.Println("Runtime:", a.runtime)
	}
	helper := langs.GetLangHelper(a.runtime)
	if helper == nil {
		fmt.Printf("init does not support the %s runtime, you'll have to create your own Dockerfile for this function", a.runtime)
	}

	if a.entrypoint == "" {
		if helper != nil {
			a.entrypoint = helper.Entrypoint()
		}
	}
	if a.cmd == "" {
		if helper != nil {
			a.cmd = helper.Cmd()
		}
	}
	if a.entrypoint == "" && a.cmd == "" {
		return fmt.Errorf("could not detect entrypoint or cmd for %v, use --entrypoint and/or --cmd to set them explicitly", a.runtime)
	}

	return nil
}

func detectRuntime(path string) (runtime string, err error) {
	for ext, runtime := range fileExtToRuntime {
		filenames := []string{
			filepath.Join(path, fmt.Sprintf("func%s", ext)),
			filepath.Join(path, fmt.Sprintf("Func%s", ext)),
			filepath.Join(path, fmt.Sprintf("src/main%s", ext)), // rust
		}
		for _, filename := range filenames {
			if exists(filename) {
				return runtime, nil
			}
		}
	}
	return "", fmt.Errorf("no supported files found to guess runtime, please set runtime explicitly with --runtime flag.")
}