From adb1b1992937b7c0e1c3297fe969aca852c4dfcf Mon Sep 17 00:00:00 2001
From: David O'Sullivan <davidos@vmware.com>
Date: Thu, 12 Aug 2021 11:29:05 +0100
Subject: [PATCH] Adds support for buildpack log level environment variable
 'BP_LOG_LEVEL' which currently accepts 'INFO' (default) or 'DEBUG'

---
 poet/logger.go      | 18 +++++++++++++++---
 poet/logger_test.go | 15 +++++++++++++++
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/poet/logger.go b/poet/logger.go
index 3799b0a..9ab6b54 100644
--- a/poet/logger.go
+++ b/poet/logger.go
@@ -57,13 +57,25 @@ func NewLoggerWithOptions(writer io.Writer, options ...Option) Logger {
 func NewLogger(writer io.Writer) Logger {
 	var options []Option
 
-	if _, ok := os.LookupEnv("BP_DEBUG"); ok {
-		options = append(options, WithDebug(writer))
-	}
+	// check for presence and value of log level environment variable
+	options = LogLevel(options, writer)
 
 	return NewLoggerWithOptions(writer, options...)
 }
 
+func LogLevel(options []Option, writer io.Writer) []Option {
+
+	// Check for older log level env variable
+	_, dbSet := os.LookupEnv("BP_DEBUG")
+
+	// Then check for common buildpack log level env variable - if either are set to DEBUG/true, enable Debug Writer
+	if level, ok := os.LookupEnv("BP_LOG_LEVEL"); (ok && strings.ToLower(level) == "debug") || dbSet {
+
+		options = append(options, WithDebug(writer))
+	}
+	return options
+}
+
 // Debug formats using the default formats for its operands and writes to the configured debug writer. Spaces are added
 // between operands when neither is a string.
 func (l Logger) Debug(a ...interface{}) {
diff --git a/poet/logger_test.go b/poet/logger_test.go
index 49d7dc4..ebf0c13 100644
--- a/poet/logger_test.go
+++ b/poet/logger_test.go
@@ -64,6 +64,21 @@ func testLogger(t *testing.T, context spec.G, it spec.S) {
 		})
 	})
 
+	context("with BP_LOG_LEVEL set to DEBUG", func() {
+		it.Before(func() {
+			Expect(os.Setenv("BP_LOG_LEVEL", "DEBUG")).To(Succeed())
+			l = poet.NewLogger(b)
+		})
+
+		it.After(func() {
+			Expect(os.Unsetenv("BP_LOG_LEVEL")).To(Succeed())
+		})
+
+		it("configures debug", func() {
+			Expect(l.IsDebugEnabled()).To(BeTrue())
+		})
+	})
+
 	context("with debug disabled", func() {
 		it.Before(func() {
 			l = poet.NewLoggerWithOptions(b)