From c1b0384777bcf2c2d7a406dcbb5a0e85e3df6b41 Mon Sep 17 00:00:00 2001
From: Adam Shannon <adamkshannon@gmail.com>
Date: Fri, 18 May 2018 10:43:14 -0500
Subject: [PATCH] config: basic_auth doesn't need to require a username

Issue: https://github.com/prometheus/prometheus/issues/4173

Signed-off-by: Adam Shannon <adamkshannon@gmail.com>
---
 config/http_config.go                         |  3 ---
 config/http_config_test.go                    | 26 +++++++++++++++++++
 .../http.conf.basic-auth.no-username.yaml     |  2 ++
 3 files changed, 28 insertions(+), 3 deletions(-)
 create mode 100644 config/testdata/http.conf.basic-auth.no-username.yaml

diff --git a/config/http_config.go b/config/http_config.go
index 59a12e95..da5d5901 100644
--- a/config/http_config.go
+++ b/config/http_config.go
@@ -85,9 +85,6 @@ func (c *HTTPClientConfig) Validate() error {
 	if c.BasicAuth != nil && (len(c.BearerToken) > 0 || len(c.BearerTokenFile) > 0) {
 		return fmt.Errorf("at most one of basic_auth, bearer_token & bearer_token_file must be configured")
 	}
-	if c.BasicAuth != nil && c.BasicAuth.Username == "" {
-		return fmt.Errorf("basic_auth requires a username")
-	}
 	if c.BasicAuth != nil && (string(c.BasicAuth.Password) != "" && c.BasicAuth.PasswordFile != "") {
 		return fmt.Errorf("at most one of basic_auth password & password_file must be configured")
 	}
diff --git a/config/http_config_test.go b/config/http_config_test.go
index bd377185..4639ae47 100644
--- a/config/http_config_test.go
+++ b/config/http_config_test.go
@@ -476,6 +476,32 @@ func TestBasicAuthNoPassword(t *testing.T) {
 	}
 }
 
+func TestBasicAuthNoUsername(t *testing.T) {
+	cfg, _, err := LoadHTTPConfigFile("testdata/http.conf.basic-auth.no-username.yaml")
+	if err != nil {
+		t.Errorf("Error loading HTTP client config: %v", err)
+	}
+	client, err := NewClientFromConfig(*cfg, "test")
+	if err != nil {
+		t.Errorf("Error creating HTTP Client: %v", err)
+	}
+
+	rt, ok := client.Transport.(*basicAuthRoundTripper)
+	if !ok {
+		t.Fatalf("Error casting to basic auth transport, %v", client.Transport)
+	}
+
+	if rt.username != "" {
+		t.Errorf("Got unexpected username: %s", rt.username)
+	}
+	if string(rt.password) != "secret" {
+		t.Errorf("Unexpected HTTP client password: %s", string(rt.password))
+	}
+	if string(rt.passwordFile) != "" {
+		t.Errorf("Expected empty HTTP client passwordFile: %s", rt.passwordFile)
+	}
+}
+
 func TestBasicAuthPasswordFile(t *testing.T) {
 	cfg, _, err := LoadHTTPConfigFile("testdata/http.conf.basic-auth.good.yaml")
 	if err != nil {
diff --git a/config/testdata/http.conf.basic-auth.no-username.yaml b/config/testdata/http.conf.basic-auth.no-username.yaml
new file mode 100644
index 00000000..86e29037
--- /dev/null
+++ b/config/testdata/http.conf.basic-auth.no-username.yaml
@@ -0,0 +1,2 @@
+basic_auth:
+  password: secret