From 7a865b2e151f54a0edf37c1884e362fc155214a3 Mon Sep 17 00:00:00 2001
From: Cameron Diver <cameron@balena.io>
Date: Wed, 18 Sep 2019 13:13:35 +0100
Subject: [PATCH] Send all debug output to stderr

Change-type: patch
Signed-off-by: Cameron Diver <cameron@balena.io>
---
 automation/build-bin.ts   | 14 +++++++++++++-
 lib/actions/push.ts       |  2 +-
 lib/utils/logger.ts       |  4 +++-
 lib/utils/remote-build.ts |  6 +++---
 4 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/automation/build-bin.ts b/automation/build-bin.ts
index f5d6149f..5c2716bc 100644
--- a/automation/build-bin.ts
+++ b/automation/build-bin.ts
@@ -22,6 +22,7 @@ import { execFile, spawn } from 'child_process';
 import { stripIndent } from 'common-tags';
 import * as filehound from 'filehound';
 import * as fs from 'fs-extra';
+import * as _ from 'lodash';
 import * as path from 'path';
 import { exec as execPkg } from 'pkg';
 import * as rimraf from 'rimraf';
@@ -348,7 +349,18 @@ async function getSubprocessStdout(
 		child.stderr.on('data', (data: Buffer) => {
 			try {
 				const stderr = data.toString();
-				reject(new Error(`"${execPath}": non-empty stderr "${stderr}"`));
+
+				// ignore any debug lines, but ensure that we parse
+				// every line provided to the stderr stream
+				const lines = _.filter(
+					stderr.trim().split(/\r?\n/),
+					line => !line.startsWith('[debug]'),
+				);
+				if (lines.length > 0) {
+					reject(
+						new Error(`"${execPath}": non-empty stderr "${lines.join('\n')}"`),
+					);
+				}
 			} catch (err) {
 				reject(err);
 			}
diff --git a/lib/actions/push.ts b/lib/actions/push.ts
index 3973d362..cd8eb950 100644
--- a/lib/actions/push.ts
+++ b/lib/actions/push.ts
@@ -268,7 +268,7 @@ export const push: CommandDefinition<
 
 		const source = options.source || '.';
 		if (process.env.DEBUG) {
-			console.log(`[debug] Using ${source} as build source`);
+			console.error(`[debug] Using ${source} as build source`);
 		}
 
 		const dockerfilePath = validateSpecifiedDockerfile(
diff --git a/lib/utils/logger.ts b/lib/utils/logger.ts
index a5fc54dd..b8005dc3 100644
--- a/lib/utils/logger.ts
+++ b/lib/utils/logger.ts
@@ -63,8 +63,10 @@ class Logger {
 		};
 
 		_.forEach(this.streams, function(stream, key) {
-			if (key !== 'debug' || process.env.DEBUG) {
+			if (key !== 'debug') {
 				stream.pipe(process.stdout);
+			} else if (process.env.DEBUG) {
+				stream.pipe(process.stderr);
 			}
 		});
 
diff --git a/lib/utils/remote-build.ts b/lib/utils/remote-build.ts
index c6879502..a22531e4 100644
--- a/lib/utils/remote-build.ts
+++ b/lib/utils/remote-build.ts
@@ -222,7 +222,7 @@ function getBuilderMessageHandler(
 ): (obj: BuilderMessage) => void {
 	return (obj: BuilderMessage) => {
 		if (DEBUG_MODE) {
-			console.log(`[debug] handling message: ${JSON.stringify(obj)}`);
+			console.error(`[debug] handling message: ${JSON.stringify(obj)}`);
 		}
 		if (obj.type != null && obj.type === 'metadata') {
 			return handleBuilderMetadata(obj, build);
@@ -318,7 +318,7 @@ function createRemoteBuildRequest(
 ): request.Request {
 	const zlib = require('zlib');
 	if (DEBUG_MODE) {
-		console.log(`[debug] Connecting to builder at ${builderUrl}`);
+		console.error(`[debug] Connecting to builder at ${builderUrl}`);
 	}
 	return request
 		.post({
@@ -331,7 +331,7 @@ function createRemoteBuildRequest(
 		.once('response', (response: request.RequestResponse) => {
 			if (response.statusCode >= 100 && response.statusCode < 400) {
 				if (DEBUG_MODE) {
-					console.log(
+					console.error(
 						`[debug] received HTTP ${response.statusCode} ${
 							response.statusMessage
 						}`,