New --exec-pipe output option

Signed-off-by: Dave Henderson <dhenderson@gmail.com>

3 files changed, 54 insertions, 1 deletions

diff --git a/cmd/gomplate/main.go b/cmd/gomplate/main.go
index a11ea931..8a0dffb7 100644
--- a/cmd/gomplate/main.go
+++ b/cmd/gomplate/main.go
@@ -5,6 +5,7 @@ The gomplate command
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"os"
 	"os/exec"
@@ -19,8 +20,11 @@ import (
 var (
 	printVer bool
 	verbose  bool
+	execPipe bool
 	opts     gomplate.Config
 	includes []string
+
+	postRunInput *bytes.Buffer
 )
 
 func printVersion(name string) {
@@ -34,7 +38,11 @@ func postRunExec(cmd *cobra.Command, args []string) error {
 		args = args[1:]
 		// nolint: gosec
 		c := exec.Command(name, args...)
-		c.Stdin = os.Stdin
+		if execPipe {
+			c.Stdin = postRunInput
+		} else {
+			c.Stdin = os.Stdin
+		}
 		c.Stderr = os.Stderr
 		c.Stdout = os.Stdout
 
@@ -101,6 +109,10 @@ func newGomplateCmd() *cobra.Command {
 			// support --include
 			opts.ExcludeGlob = processIncludes(includes, opts.ExcludeGlob)
 
+			if execPipe {
+				postRunInput = &bytes.Buffer{}
+				opts.Out = postRunInput
+			}
 			err := gomplate.RunTemplates(&opts)
 			cmd.SilenceErrors = true
 			cmd.SilenceUsage = true
@@ -140,6 +152,8 @@ func initFlags(command *cobra.Command) {
 	command.Flags().StringVar(&opts.OutputMap, "output-map", "", "Template `string` to map the input file to an output path")
 	command.Flags().StringVar(&opts.OutMode, "chmod", "", "set the mode for output file(s). Omit to inherit from input file(s)")
 
+	command.Flags().BoolVar(&execPipe, "exec-pipe", false, "pipe the output to the post-run exec command")
+
 	ldDefault := env.Getenv("GOMPLATE_LEFT_DELIM", "{{")
 	rdDefault := env.Getenv("GOMPLATE_RIGHT_DELIM", "}}")
 	command.Flags().StringVar(&opts.LDelim, "left-delim", ldDefault, "override the default left-`delimiter` [$GOMPLATE_LEFT_DELIM]")
diff --git a/cmd/gomplate/validate.go b/cmd/gomplate/validate.go
index 68c132b8..f4c73133 100644
--- a/cmd/gomplate/validate.go
+++ b/cmd/gomplate/validate.go
@@ -47,6 +47,10 @@ func validateOpts(cmd *cobra.Command, args []string) (err error) {
 		err = fmt.Errorf("must provide same number of --out (%d) as --file (%d) options", len(opts.OutputFiles), len(opts.InputFiles))
 	}
 
+	if err == nil && cmd.Flag("exec-pipe").Changed && len(args) == 0 {
+		err = fmt.Errorf("--exec-pipe may only be used with a post-exec command after --")
+	}
+
 	if err == nil {
 		err = mustTogether(cmd, "output-dir", "input-dir")
 	}
diff --git a/cmd/gomplate/validate_test.go b/cmd/gomplate/validate_test.go
index 91f16767..54f4ba01 100644
--- a/cmd/gomplate/validate_test.go
+++ b/cmd/gomplate/validate_test.go
@@ -42,6 +42,41 @@ func TestValidateOpts(t *testing.T) {
 	))
 	assert.Error(t, err)
 
+	err = validateOpts(parseFlags("--exec-pipe"))
+	assert.Error(t, err)
+
+	err = validateOpts(parseFlags("--exec-pipe", "--"))
+	assert.Error(t, err)
+
+	err = validateOpts(parseFlags(
+		"--exec-pipe",
+		"--", "echo", "foo",
+	))
+	assert.NoError(t, err)
+
+	err = validateOpts(parseFlags(
+		"--exec-pipe",
+		"--out", "foo",
+		"--", "echo",
+	))
+	assert.Error(t, err)
+
+	err = validateOpts(parseFlags(
+		"--input-dir", "in",
+		"--exec-pipe",
+		"--output-dir", "foo",
+		"--", "echo",
+	))
+	assert.Error(t, err)
+
+	err = validateOpts(parseFlags(
+		"--input-dir", "in",
+		"--exec-pipe",
+		"--output-map", "foo",
+		"--", "echo",
+	))
+	assert.Error(t, err)
+
 	err = validateOpts(parseFlags(
 		"--input-dir", "in",
 		"--output-map", "bar",