tfexec: Add (Terraform).SetLog() method

tfexec/cmd.go

@@ -149,8 +149,7 @@ func (tf *Terraform) buildEnv(mergeEnv map[string]string) []string {
 		env[logPathEnvVar] = ""
 	} else {
 		env[logPathEnvVar] = tf.logPath
-		// Log levels other than TRACE are currently unreliable, the CLI recommends using TRACE only.
-		env[logEnvVar] = "TRACE"
+		env[logEnvVar] = tf.log
 	}
 
 	// constant automation override env vars

tfexec/terraform.go

@@ -48,9 +48,14 @@ type Terraform struct {
 	skipProviderVerify bool
 	env                map[string]string
 
-	stdout  io.Writer
-	stderr  io.Writer
-	logger  printfer
+	stdout io.Writer
+	stderr io.Writer
+	logger printfer
+
+	// TF_LOG environment variable, defaults to TRACE if logPath is set.
+	log string
+
+	// TF_LOG_PATH environment variable
 	logPath string
 
 	versionLock  sync.Mutex
@@ -122,10 +127,29 @@ func (tf *Terraform) SetStderr(w io.Writer) {
 	tf.stderr = w
 }
 
+// SetLog sets the TF_LOG environment variable for Terraform CLI execution.
+// This must be combined with a call to SetLogPath to take effect.
+//
+// This is only compatible with Terraform CLI 0.15.0 or later as setting the
+// log level was unreliable in earlier versions. It will default to TRACE for
+// those earlier versions when SetLogPath is called.
+func (tf *Terraform) SetLog(log string) error {
+	err := tf.compatible(context.Background(), tf0_15_0, nil)
+	if err != nil {
+		return err
+	}
+	tf.log = log
+	return nil
+}
+
 // SetLogPath sets the TF_LOG_PATH environment variable for Terraform CLI
 // execution.
 func (tf *Terraform) SetLogPath(path string) error {
 	tf.logPath = path
+	// Prevent setting the log path without enabling logging
+	if tf.log == "" {
+		tf.log = "TRACE"
+	}
 	return nil
 }
 

tfexec/terraform_test.go

@@ -5,6 +5,8 @@ import (
 	"errors"
 	"io/ioutil"
 	"os"
+	"path/filepath"
+	"runtime"
 	"testing"
 
 	"github.com/hashicorp/terraform-exec/tfexec/internal/testutil"
@@ -61,6 +63,215 @@ func TestSetEnv(t *testing.T) {
 	}
 }
 
+func TestSetLog(t *testing.T) {
+	td := t.TempDir()
+
+	tf, err := NewTerraform(td, tfVersion(t, testutil.Latest_v1))
+
+	if err != nil {
+		t.Fatalf("unexpected NewTerraform error: %s", err)
+	}
+
+	// Required so all testing environment variables are not copied.
+	err = tf.SetEnv(map[string]string{
+		"CLEARENV": "1",
+	})
+
+	if err != nil {
+		t.Fatalf("unexpected SetEnv error: %s", err)
+	}
+
+	t.Run("case 1: SetLog <= 0.15 error", func(t *testing.T) {
+		if runtime.GOOS == "darwin" && runtime.GOARCH == "arm64" {
+			t.Skip("Terraform for darwin/arm64 is not available until v1")
+		}
+
+		td012 := t.TempDir()
+
+		tf012, err := NewTerraform(td012, tfVersion(t, testutil.Latest012))
+
+		if err != nil {
+			t.Fatalf("unexpected NewTerraform error: %s", err)
+		}
+
+		err = tf012.SetLog("TRACE")
+
+		if err == nil {
+			t.Fatal("expected SetLog error, got none")
+		}
+	})
+
+	t.Run("case 2: SetLog TRACE no SetLogPath", func(t *testing.T) {
+		err := tf.SetLog("TRACE")
+
+		if err != nil {
+			t.Fatalf("unexpected SetLog error: %s", err)
+		}
+
+		initCmd, err := tf.initCmd(context.Background())
+
+		if err != nil {
+			t.Fatalf("unexpected command error: %s", err)
+		}
+
+		assertCmd(t, []string{
+			"init",
+			"-no-color",
+			"-force-copy",
+			"-input=false",
+			"-backend=true",
+			"-get=true",
+			"-upgrade=false",
+		}, map[string]string{
+			"CLEARENV": "1",
+			"TF_LOG":   "",
+		}, initCmd)
+	})
+
+	t.Run("case 3: SetLog TRACE and SetLogPath", func(t *testing.T) {
+		tfLogPath := filepath.Join(td, "test.log")
+
+		err := tf.SetLog("TRACE")
+
+		if err != nil {
+			t.Fatalf("unexpected SetLog error: %s", err)
+		}
+
+		err = tf.SetLogPath(tfLogPath)
+
+		if err != nil {
+			t.Fatalf("unexpected SetLogPath error: %s", err)
+		}
+
+		initCmd, err := tf.initCmd(context.Background())
+
+		if err != nil {
+			t.Fatalf("unexpected command error: %s", err)
+		}
+
+		assertCmd(t, []string{
+			"init",
+			"-no-color",
+			"-force-copy",
+			"-input=false",
+			"-backend=true",
+			"-get=true",
+			"-upgrade=false",
+		}, map[string]string{
+			"CLEARENV":    "1",
+			"TF_LOG":      "TRACE",
+			"TF_LOG_PATH": tfLogPath,
+		}, initCmd)
+	})
+
+	t.Run("case 4: SetLog DEBUG and SetLogPath", func(t *testing.T) {
+		tfLogPath := filepath.Join(td, "test.log")
+
+		err := tf.SetLog("DEBUG")
+
+		if err != nil {
+			t.Fatalf("unexpected SetLog error: %s", err)
+		}
+
+		err = tf.SetLogPath(tfLogPath)
+
+		if err != nil {
+			t.Fatalf("unexpected SetLogPath error: %s", err)
+		}
+
+		initCmd, err := tf.initCmd(context.Background())
+
+		if err != nil {
+			t.Fatalf("unexpected command error: %s", err)
+		}
+
+		assertCmd(t, []string{
+			"init",
+			"-no-color",
+			"-force-copy",
+			"-input=false",
+			"-backend=true",
+			"-get=true",
+			"-upgrade=false",
+		}, map[string]string{
+			"CLEARENV":    "1",
+			"TF_LOG":      "DEBUG",
+			"TF_LOG_PATH": tfLogPath,
+		}, initCmd)
+	})
+}
+
+func TestSetLogPath(t *testing.T) {
+	td := t.TempDir()
+
+	tf, err := NewTerraform(td, tfVersion(t, testutil.Latest_v1))
+
+	if err != nil {
+		t.Fatalf("unexpected NewTerraform error: %s", err)
+	}
+
+	// Required so all testing environment variables are not copied.
+	err = tf.SetEnv(map[string]string{
+		"CLEARENV": "1",
+	})
+
+	if err != nil {
+		t.Fatalf("unexpected SetEnv error: %s", err)
+	}
+
+	t.Run("case 1: No SetLogPath", func(t *testing.T) {
+		initCmd, err := tf.initCmd(context.Background())
+
+		if err != nil {
+			t.Fatalf("unexpected command error: %s", err)
+		}
+
+		assertCmd(t, []string{
+			"init",
+			"-no-color",
+			"-force-copy",
+			"-input=false",
+			"-backend=true",
+			"-get=true",
+			"-upgrade=false",
+		}, map[string]string{
+			"CLEARENV":    "1",
+			"TF_LOG":      "",
+			"TF_LOG_PATH": "",
+		}, initCmd)
+	})
+
+	t.Run("case 2: SetLogPath sets TF_LOG and TF_LOG_PATH", func(t *testing.T) {
+		tfLogPath := filepath.Join(td, "test.log")
+
+		err = tf.SetLogPath(tfLogPath)
+
+		if err != nil {
+			t.Fatalf("unexpected SetLogPath error: %s", err)
+		}
+
+		initCmd, err := tf.initCmd(context.Background())
+
+		if err != nil {
+			t.Fatalf("unexpected command error: %s", err)
+		}
+
+		assertCmd(t, []string{
+			"init",
+			"-no-color",
+			"-force-copy",
+			"-input=false",
+			"-backend=true",
+			"-get=true",
+			"-upgrade=false",
+		}, map[string]string{
+			"CLEARENV":    "1",
+			"TF_LOG":      "TRACE",
+			"TF_LOG_PATH": tfLogPath,
+		}, initCmd)
+	})
+}
+
 func TestCheckpointDisablePropagation(t *testing.T) {
 	td := t.TempDir()