Discard log messages when initializing the provider (#4650)

Messages sent early to the "log" package end up being forwarded to
stderr, and Pulumi displays stderr by default to users, which is
undesirable.

Later in the provider life-cycle, Pulumi Terraform Bridge will reset
`log.SetOutput` again to capture and appropriately track diagnostic
logs, which should still work with this change.

Fixes #4645

A test is added to ensure we do not leak diagnostics again on a simple
program.

provider/provider_nodejs_test.go

@@ -313,6 +313,66 @@ func TestRegress4568(t *testing.T) {
 	})
 }
 
+// Tests that there are no diagnostics by default on simple programs.
+func TestNoExtranousLogOutput(t *testing.T) {
+	skipIfShort(t)
+	dir := filepath.Join("test-programs", "bucket-obj")
+	cwd, err := os.Getwd()
+	require.NoError(t, err)
+	providerName := "aws"
+	options := []opttest.Option{
+		opttest.LocalProviderPath(providerName, filepath.Join(cwd, "..", "bin")),
+	}
+	test := pulumitest.NewPulumiTest(t, dir, options...)
+	result := test.Preview(t)
+	assert.NotContainsf(t, result.StdOut, "Diagnostics:",
+		"No diagnostics should be emitted to stdout for simple programs")
+	assert.NotContainsf(t, result.StdErr, "Diagnostics:",
+		"No diagnostics should be emitted to stderr for simple programs")
+}
+
+// Since AWS is doing something non-standard with logging, double-check that `log.Printf` messages do get propagated
+// when TF_LOG=DEBUG is set. One such message is set by aws.s3.Bucketv2 when refresh finds that the bucket no longer
+// exists. Emulate this situation and assert that the message has propagated.
+func TestUpstreamWarningsPropagated(t *testing.T) {
+	skipIfShort(t)
+	dir := filepath.Join("test-programs", "disappearing-bucket-object")
+	cwd, err := os.Getwd()
+	require.NoError(t, err)
+	providerName := "aws"
+	options := []opttest.Option{
+		opttest.LocalProviderPath(providerName, filepath.Join(cwd, "..", "bin")),
+		opttest.YarnLink("@pulumi/aws"),
+		opttest.Env("TF_LOG", "DEBUG"),
+	}
+	test := pulumitest.NewPulumiTest(t, dir, options...)
+
+	t.Logf("Creating the bucket object")
+	test.Up(t)
+
+	state := test.ExportStack(t)
+
+	t.Logf("Deleting the bucket object")
+	test.SetConfig(t, "bucket-object", "exclude")
+	test.Up(t)
+
+	t.Logf("Resetting the state back")
+	test.ImportStack(t, state)
+
+	t.Logf("Refreshing the stack and expecting bucket to be deleted from the state")
+	rr := test.Refresh(t)
+	t.Logf("%v%v", rr.StdOut, rr.StdErr)
+
+	// Upstream code has this line:
+	//
+	//     log.Printf("[WARN] S3 Object (%s) not found, removing from state", d.Id())
+	//
+	assert.Containsf(t,
+		rr.StdErr+rr.StdOut,
+		"warning: S3 Object (index.ts) not found, removing from state",
+		"Expected upstream log.Printf to propagate under TF_LOG=DEBUG")
+}
+
 func getJSBaseOptions(t *testing.T) integration.ProgramTestOptions {
 	envRegion := getEnvRegion(t)
 	baseJS := integration.ProgramTestOptions{

provider/test-programs/disappearing-bucket-object/Pulumi.yaml

@@ -0,0 +1,2 @@
+name: disappearing-bucket-object
+runtime: nodejs

provider/test-programs/disappearing-bucket-object/index.ts

@@ -0,0 +1,13 @@
+import * as aws from "@pulumi/aws";
+import * as pulumi from "@pulumi/pulumi";
+
+const cfg = new pulumi.Config();
+const b = new aws.s3.BucketV2("my-bucket", {});
+
+if (cfg.get("bucket-object") !== "exclude") {
+    const o = new aws.s3.BucketObjectv2("obj", {
+        bucket: b.bucket,
+        key: "index.ts",
+        source: new pulumi.asset.FileAsset("index.ts"),
+    });
+}

provider/test-programs/disappearing-bucket-object/package.json

@@ -0,0 +1,15 @@
+{
+    "name": "disappearing-bucket-object",
+    "version": "0.1.0",
+    "license": "Apache-2.0",
+    "scripts": {
+        "build": "tsc"
+    },
+    "dependencies": {
+        "@pulumi/pulumi": "^3.0.0",
+        "@pulumi/aws": "^6.0.0"
+    },
+    "devDependencies": {
+        "@types/node": "^8.0.0"
+    }
+}

provider/test-programs/disappearing-bucket-object/tsconfig.json

@@ -0,0 +1,18 @@
+{
+    "compilerOptions": {
+        "outDir": "bin",
+        "target": "es2016",
+        "module": "commonjs",
+        "moduleResolution": "node",
+        "sourceMap": true,
+        "experimentalDecorators": true,
+        "pretty": true,
+        "noFallthroughCasesInSwitch": true,
+        "noImplicitReturns": true,
+        "forceConsistentCasingInFileNames": true,
+        "strictNullChecks": true
+    },
+    "files": [
+        "index.ts"
+    ]
+}

provider/upstream_provider.go

@@ -16,6 +16,9 @@ package provider
 
 import (
 	"context"
+	"io"
+	"log"
+	"os"
 
 	awsShim "github.com/hashicorp/terraform-provider-aws/shim"
 	"github.com/pulumi/pulumi-aws/provider/v6/pkg/rds"
@@ -30,6 +33,9 @@ import (
 // runtime startup is somewhat performance sensitive. Therefore any modifications undertaken here should complete
 // quickly.
 func newUpstreamProvider(ctx context.Context) awsShim.UpstreamProvider {
+	log.SetOutput(io.Discard)      // ignore logging from upstream constructors
+	defer log.SetOutput(os.Stderr) // revert to default
+
 	upstreamProvider, err := awsShim.NewUpstreamProvider(ctx)
 	contract.AssertNoErrorf(err, "NewUpstreamProvider failed to initialize")
 	rds.ReconfigureResources(upstreamProvider.SDKV2Provider)