From 122288ee4798f7b975f8f19fdfd29c38f73bc368 Mon Sep 17 00:00:00 2001
From: Yusuke Kuoka <ykuoka@gmail.com>
Date: Tue, 11 Feb 2020 10:28:59 +0900
Subject: [PATCH] feat: `variant export binary SRC_DIR DST_FILE` to build a
 single executable binary at DST_FILE

---
 Makefile            |  5 +++++
 README.md           | 18 ++++++++++++++++++
 export_binary.go    | 26 ++++++++++++++++++++++++++
 pkg/app/app_shim.go | 27 +++++++++++++++++++++++++++
 variant.go          |  1 +
 5 files changed, 77 insertions(+)
 create mode 100644 export_binary.go

diff --git a/Makefile b/Makefile
index 87111b3..816a61c 100644
--- a/Makefile
+++ b/Makefile
@@ -33,3 +33,8 @@ smoke: build
 	go build -o build/simple/simple ./build/simple
 	build/simple/simple -h | tee smoke.log
 	grep "Namespace to interact with" smoke.log
+
+	rm build/simple/simple
+	./variant export binary examples/simple build/simple
+	build/simple/simple -h | tee smoke2.log
+	grep "Namespace to interact with" smoke2.log
diff --git a/README.md b/README.md
index 7edb86e..55e482c 100644
--- a/README.md
+++ b/README.md
@@ -123,6 +123,24 @@ As you've seen in the help output, `variant run deploy` runs the `deploy` job, w
 $ variant run deploy
 ```
 
+Once you're finished developing the command, let's build a single executable binary of the command for easy distribution:
+
+```console
+$ variant export binary ./ build/myapp
+```
+
+The exported executable binary accepts the same arguments as `variant run`:
+
+```console
+$ ./build/myapp -h
+
+$ ./build/myapp run deploy
+```
+
+Congratulations! You're now ready to dive deep and solve your own problems with Variant.
+
+Still curious how Variant helps developing your own command as it grows?
+
 Head over to the following per-topic sections for more features:
 
 - [Generating Shims](#generating-shims) to make your Variant command look native
diff --git a/export_binary.go b/export_binary.go
new file mode 100644
index 0000000..c6703e1
--- /dev/null
+++ b/export_binary.go
@@ -0,0 +1,26 @@
+package variant
+
+import (
+	"github.com/spf13/cobra"
+)
+
+func newExportBinary(r *Runner) *cobra.Command {
+	return &cobra.Command{
+		Use:   "binary SRC_DIR DST_FILE",
+		Short: "Builds the single executable binary of the Variant command defined in SRC_DIR. Basically `variant export go SRC_DIR TMP_DIR && go build -o DST_FILE TMP_DIR`",
+		Example: `$ variant export binary examples/simple build/simple
+
+$ build/simple -h
+
+$ build/simple app deploy -n default
+`,
+		Args: cobra.ExactArgs(2),
+		RunE: func(c *cobra.Command, args []string) error {
+			err := r.ap.ExportBinary(args[0], args[1])
+			if err != nil {
+				c.SilenceUsage = true
+			}
+			return err
+		},
+	}
+}
diff --git a/pkg/app/app_shim.go b/pkg/app/app_shim.go
index 2a96dc9..494f2b4 100644
--- a/pkg/app/app_shim.go
+++ b/pkg/app/app_shim.go
@@ -13,6 +13,33 @@ import (
 	"github.com/mumoshu/variant2/pkg/conf"
 )
 
+func (app *App) ExportBinary(srcDir, dstFile string) error {
+	tmpDir, err := ioutil.TempDir("", "variant-"+filepath.Base(srcDir))
+	if err != nil {
+		return err
+	}
+
+	defer os.RemoveAll(tmpDir)
+
+	if err := app.ExportGo(srcDir, tmpDir); err != nil {
+		return err
+	}
+
+	if err := os.MkdirAll(filepath.Dir(dstFile), 0755); err != nil {
+		return err
+	}
+
+	absDstFile, err := filepath.Abs(dstFile)
+
+	if err != nil {
+		return err
+	}
+
+	_, err = app.execCmd("sh", []string{"-c", fmt.Sprintf("cd %s; go mod init %s && go build -o %s %s", tmpDir, filepath.Base(srcDir), absDstFile, tmpDir)}, map[string]string{}, true)
+
+	return err
+}
+
 func (app *App) ExportGo(srcDir, dstDir string) error {
 	if err := os.MkdirAll(dstDir, 0755); err != nil {
 		return err
diff --git a/variant.go b/variant.go
index 7eeac0b..f3c3255 100644
--- a/variant.go
+++ b/variant.go
@@ -764,6 +764,7 @@ func (r *Runner) createVariantRootCommand() *cobra.Command {
 
 		exportCmd.AddCommand(shimCmd)
 		exportCmd.AddCommand(newExportGo(r))
+		exportCmd.AddCommand(newExportBinary(r))
 	}
 
 	generateCmd := &cobra.Command{