Allow to specify template when running dagger project init

Adds the ability to select a template which will create a new file
in the CWD with the template name. Templates present in the
"cmd/dagger/project/templates" directory are automatically embedded in the dagger
binary when building and then listed in the `dagger project init` help output.

Usage:

    dagger project init -t <template_name>

One idea that we had while pairing on this is to eventually try
improving this UX by extending the `dagger project` command by adding
sub-commands like `dagger project templates [list, new, output, ...]`.

Pair: gerhard

Signed-off-by: Marcos Lilljedahl <marcosnils@gmail.com>

cmd/dagger/cmd/project/init.go

@@ -33,8 +33,17 @@ var initCmd = &cobra.Command{
 			dir = args[0]
 		}
 
-		name := viper.GetString("name")
+		// TODO @gerhard suggested maybe eventually having a
+		// `dagger project template [list, new]`
+		t := viper.GetString("template")
+		if len(t) > 0 {
+			err := createTemplate(t)
+			if err != nil {
+				lg.Fatal().Err(err).Msg("failed to initialize template")
+			}
+		}
 
+		name := viper.GetString("name")
 		doneCh := common.TrackCommand(ctx, cmd)
 		err := pkg.CueModInit(ctx, dir, name)
 		<-doneCh
@@ -46,6 +55,11 @@ var initCmd = &cobra.Command{
 
 func init() {
 	initCmd.Flags().StringP("name", "n", "", "project name")
+	t, err := getTemplateNames()
+	if err != nil {
+		panic(err)
+	}
+	initCmd.Flags().StringP("template", "t", "", fmt.Sprintf("Template name %s", t))
 	if err := viper.BindPFlags(initCmd.Flags()); err != nil {
 		panic(err)
 	}

cmd/dagger/cmd/project/template.go

@@ -0,0 +1,50 @@
+package project
+
+import (
+	"embed"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+//go:embed templates/*.cue
+var templateFS embed.FS
+
+func createTemplate(name string) error {
+	filename := fmt.Sprintf("%s.cue", name)
+	f, err := templateFS.Open(fmt.Sprintf("templates/%s", filename))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	fout, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+
+	defer fout.Close()
+
+	_, err = io.Copy(fout, f)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func getTemplateNames() ([]string, error) {
+	r := []string{}
+	e, err := templateFS.ReadDir("templates")
+	if err != nil {
+		return nil, err
+	}
+
+	for _, f := range e {
+		r = append(r, strings.TrimSuffix(f.Name(), filepath.Ext(f.Name())))
+	}
+
+	return r, nil
+}

cmd/dagger/cmd/project/templates/hello.cue

@@ -0,0 +1,28 @@
+// The first time you run the hello
+// action as `dagger do hello --log-format plain`,
+// make sure to run `dagger project update` first,
+// so that all required dependencies are available.
+
+package hello
+
+import (
+	"dagger.io/dagger"
+	"universe.dagger.io/bash"
+	"universe.dagger.io/alpine"
+
+)
+
+dagger.#Plan & {
+	actions: {
+		_alpine: alpine.#Build & {
+			packages: bash: _
+		}
+
+		// Hello world
+		hello: bash.#Run & {
+			input: _alpine.output
+			script: contents: "echo Hello World"
+			always: true
+		}
+	}
+}

tests/package.json

@@ -4,7 +4,7 @@
     "test": "bats --jobs 4 --print-output-on-failure --verbose-run ."
   },
   "devDependencies": {
-    "bats": "https://github.com/bats-core/bats-core#master",
+    "bats": "https://github.com/bats-core/bats-core#v1.6.0",
     "bats-assert": "https://github.com/bats-core/bats-assert",
     "bats-support": "https://github.com/bats-core/bats-support"
   }

tests/project.bats

@@ -8,7 +8,7 @@ setup() {
 }
 
 @test "project init and update and info" {
-	cd "$TEMPDIR" || exit
+	cd "$TEMPDIR" || exit 1
 
 	"$DAGGER" project init ./ --name "github.com/foo/bar"
 	test -d ./cue.mod/pkg
@@ -39,3 +39,27 @@ setup() {
 	assert_failure
 	assert_output --partial "dagger project not found. Run \`dagger project init\`"
 }
+
+
+@test "project init with template" {
+  cd "$TEMPDIR" || exit 1
+
+  if test -f ./hello.cue
+  then
+    echo "./hello.cue should not exist"
+    exit 1
+  fi
+
+  run "$DAGGER" project init -t hello
+
+  assert_success
+
+  if test ! -f ./hello.cue
+  then
+    echo "./hello.cue file was not created by the template flag"
+    exit 1
+  fi
+
+  cd -
+  diff --unified "$TEMPDIR/hello.cue" "$TESTDIR/../cmd/dagger/cmd/project/templates/hello.cue"
+}