core: use same logging setup for acctests

We weren't doing any log setup for acceptance tests, which made it
difficult to wrangle log output in CI.

This moves the log setup functions we use in `main` over into a helper
package so we can use them for acceptance tests as well.

This means that acceptance tests will by default be a _lot_ quieter,
only printing out actual test output. Setting `TF_LOG=trace` will
restore the full prior noise level.

Only minor behavior change is to make `ioutil.Discard` the default
return value rather than a `nil` that needs to be checked for.

helper/logging/logging.go

@@ -1,7 +1,8 @@
-package main
+package logging
 
 import (
 	"io"
+	"io/ioutil"
 	"log"
 	"os"
 	"strings"
@@ -18,9 +19,9 @@ const (
 
 var validLevels = []logutils.LogLevel{"TRACE", "DEBUG", "INFO", "WARN", "ERROR"}
 
-// logOutput determines where we should send logs (if anywhere) and the log level.
+// LogOutput determines where we should send logs (if anywhere) and the log level.
-func logOutput() (logOutput io.Writer, err error) {
+func LogOutput() (logOutput io.Writer, err error) {
-	logOutput = nil
+	logOutput = ioutil.Discard
 	envLevel := os.Getenv(EnvLog)
 	if envLevel == "" {
 		return

helper/resource/testing.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/hashicorp/go-getter"
 	"github.com/hashicorp/terraform/config/module"
+	"github.com/hashicorp/terraform/helper/logging"
 	"github.com/hashicorp/terraform/terraform"
 )
 
@@ -103,6 +104,12 @@ func Test(t TestT, c TestCase) {
 		return
 	}
 
+	logWriter, err := logging.LogOutput()
+	if err != nil {
+		t.Error(fmt.Errorf("error setting up logging: %s", err))
+	}
+	log.SetOutput(logWriter)
+
 	// We require verbose mode so that the user knows what is going on.
 	if !testTesting && !testing.Verbose() {
 		t.Fatal("Acceptance tests must be run with the -v flag on tests")

main.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"sync"
 
+	"github.com/hashicorp/terraform/helper/logging"
 	"github.com/hashicorp/terraform/plugin"
 	"github.com/mitchellh/cli"
 	"github.com/mitchellh/panicwrap"
@@ -23,14 +24,11 @@ func realMain() int {
 
 	if !panicwrap.Wrapped(&wrapConfig) {
 		// Determine where logs should go in general (requested by the user)
-		logWriter, err := logOutput()
+		logWriter, err := logging.LogOutput()
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Couldn't setup log output: %s", err)
 			return 1
 		}
-		if logWriter == nil {
-			logWriter = ioutil.Discard
-		}
 
 		// We always send logs to a temporary file that we use in case
 		// there is a panic. Otherwise, we delete it.
@@ -42,10 +40,6 @@ func realMain() int {
 		defer os.Remove(logTempFile.Name())
 		defer logTempFile.Close()
 
-		// Tell the logger to log to this file
-		os.Setenv(EnvLog, "")
-		os.Setenv(EnvLogFile, "")
-
 		// Setup the prefixed readers that send data properly to
 		// stdout/stderr.
 		doneCh := make(chan struct{})