backend: Add realtime output on building phase

The realtime output could be configured through
LUET_GENERAL__SHOW_BUILD_OUTPUT environment
variable or related config option or through
`--live-output` option.

cmd/build.go

@@ -83,6 +83,8 @@ Build packages specifying multiple definition trees:
 		LuetCfg.Viper.BindPFlag("solver.discount", cmd.Flags().Lookup("solver-discount"))
 		LuetCfg.Viper.BindPFlag("solver.rate", cmd.Flags().Lookup("solver-rate"))
 		LuetCfg.Viper.BindPFlag("solver.max_attempts", cmd.Flags().Lookup("solver-attempts"))
+		LuetCfg.Viper.BindPFlag("general.show_build_output", cmd.Flags().Lookup("live-output"))
+
 	},
 	Run: func(cmd *cobra.Command, args []string) {
 
@@ -155,6 +157,8 @@ Build packages specifying multiple definition trees:
 		LuetCfg.GetSolverOptions().Discount = float32(discount)
 		LuetCfg.GetSolverOptions().MaxAttempts = attempts
 
+		LuetCfg.GetGeneral().ShowBuildOutput = LuetCfg.Viper.GetBool("general.show_build_output")
+
 		Debug("Solver", LuetCfg.GetSolverOptions().CompactString())
 
 		opts := compiler.NewDefaultCompilerOptions()
@@ -317,6 +321,7 @@ func init() {
 	buildCmd.Flags().Float32("solver-discount", 1.0, "Solver discount rate")
 	buildCmd.Flags().Int("solver-attempts", 9000, "Solver maximum attempts")
 	buildCmd.Flags().Bool("solver-concurrent", false, "Use concurrent solver (experimental)")
+	buildCmd.Flags().Bool("live-output", LuetCfg.GetGeneral().ShowBuildOutput, "Enable live output of the build phase.")
 
 	buildCmd.Flags().Bool("pretend", false, "Just print what packages will be compiled")
 

pkg/compiler/backend/common.go

@@ -16,8 +16,15 @@
 package backend
 
 import (
-	"github.com/google/go-containerregistry/pkg/crane"
+	"fmt"
+	"os/exec"
+
 	"github.com/mudler/luet/pkg/compiler"
+	"github.com/mudler/luet/pkg/config"
+	. "github.com/mudler/luet/pkg/logger"
+
+	"github.com/google/go-containerregistry/pkg/crane"
+	"github.com/pkg/errors"
 )
 
 const (
@@ -41,3 +48,45 @@ func NewBackend(s string) compiler.CompilerBackend {
 	}
 	return compilerBackend
 }
+
+func runCommand(cmd *exec.Cmd) (string, error) {
+	ans := ""
+	writer := NewBackendWriter(!config.LuetCfg.GetGeneral().ShowBuildOutput)
+
+	if config.LuetCfg.GetGeneral().ShowBuildOutput {
+		// We have realtime output from command. Quiet spinner.
+		SpinnerStop()
+	}
+
+	cmd.Stdout = writer
+	cmd.Stderr = writer
+
+	err := cmd.Start()
+	if err != nil {
+		return "", errors.Wrap(err, "Failed starting build")
+	}
+
+	err = cmd.Wait()
+	if err != nil {
+		return "", errors.Wrap(err, "Failed waiting for building command")
+	}
+
+	res := cmd.ProcessState.ExitCode()
+	if res != 0 {
+		errMsg := fmt.Sprintf("Failed building image (exiting with %d)", res)
+		if !config.LuetCfg.GetGeneral().ShowBuildOutput {
+			errMsg = fmt.Sprintf("Failed building image (exiting with %d): %s",
+				res, writer.GetCombinedOutput())
+		}
+
+		return "", errors.Wrap(err, errMsg)
+	}
+
+	if config.LuetCfg.GetGeneral().ShowBuildOutput {
+		Spinner(22)
+	} else {
+		ans = writer.GetCombinedOutput()
+	}
+
+	return ans, nil
+}

pkg/compiler/backend/simpledocker.go

@@ -56,10 +56,11 @@ func (*SimpleDocker) BuildImage(opts compiler.CompilerBackendOptions) error {
 	Info(":whale2: Building image " + name)
 	cmd := exec.Command("docker", buildarg...)
 	cmd.Dir = path
-	out, err := cmd.CombinedOutput()
+	_, err := runCommand(cmd)
 	if err != nil {
-		return errors.Wrap(err, "Failed building image: "+string(out))
+		return err
 	}
+
 	Info(":whale: Building image " + name + " done")
 
 	if os.Getenv("DOCKER_SQUASH") == "true" {
@@ -77,12 +78,6 @@ func (*SimpleDocker) BuildImage(opts compiler.CompilerBackendOptions) error {
 		Info(":whale: Squashing image " + name + " done")
 	}
 
-	if config.LuetCfg.GetGeneral().ShowBuildOutput {
-		Info(string(out))
-	} else {
-		Debug(string(out))
-	}
-
 	return nil
 }
 

pkg/compiler/backend/simpleimg.go

@@ -44,17 +44,17 @@ func (*SimpleImg) BuildImage(opts compiler.CompilerBackendOptions) error {
 	dockerfileName := opts.DockerFileName
 
 	buildarg := []string{"build", "-f", dockerfileName, "-t", name, context}
-	Spinner(22)
-	defer SpinnerStop()
+
 	Info(":tea: Building image " + name)
 	cmd := exec.Command("img", buildarg...)
 	cmd.Dir = path
-	out, err := cmd.CombinedOutput()
-
+	_, err := runCommand(cmd)
 	if err != nil {
-		return errors.Wrap(err, "Failed building image: "+string(out))
+		return err
 	}
+
 	Info(":tea: Building image " + name + " done")
+
 	return nil
 }
 

pkg/compiler/backend/writer.go

@@ -0,0 +1,45 @@
+// Copyright © 2021 Daniele Rondina <geaaru@sabayonlinux.org>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, see <http://www.gnu.org/licenses/>.
+
+package backend
+
+import (
+	"bytes"
+
+	. "github.com/mudler/luet/pkg/logger"
+)
+
+type BackendWriter struct {
+	BufferedOutput bool
+	Buffer         bytes.Buffer
+}
+
+func NewBackendWriter(buffered bool) *BackendWriter {
+	return &BackendWriter{
+		BufferedOutput: buffered,
+	}
+}
+
+func (b *BackendWriter) Write(p []byte) (int, error) {
+	if b.BufferedOutput {
+		return b.Buffer.Write(p)
+	} else {
+		Msg("info", false, false, (string(p)))
+	}
+	return len(p), nil
+}
+
+func (b *BackendWriter) Close() error              { return nil }
+func (b *BackendWriter) GetCombinedOutput() string { return b.Buffer.String() }