PUPPETDB SD: Validate HTTP config

Related-to #12810

Signed-off-by: Jayapriya Pai <janantha@redhat.com>

config/config_test.go

@@ -1825,6 +1825,10 @@ var expectedErrors = []struct {
 		filename: "puppetdb_no_scheme.bad.yml",
 		errMsg:   "URL scheme must be 'http' or 'https'",
 	},
+	{
+		filename: "puppetdb_token_file.bad.yml",
+		errMsg:   "at most one of bearer_token & bearer_token_file must be configured",
+	},
 	{
 		filename: "hetzner_role.bad.yml",
 		errMsg:   "unknown role",

config/testdata/puppetdb_token_file.bad.yml

@@ -0,0 +1,7 @@
+scrape_configs:
+- job_name: puppetdb
+  puppetdb_sd_configs:
+  - url: http://puppet
+    query: 'resources { type = "Package" and title = "httpd" }'
+    bearer_token: foo
+    bearer_token_file: foo

discovery/puppetdb/puppetdb.go

@@ -115,7 +115,7 @@ func (c *SDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	if c.Query == "" {
 		return fmt.Errorf("query missing")
 	}
-	return nil
+	return c.HTTPClientConfig.Validate()
 }
 
 // Discovery provides service discovery functionality based