honor CONSUL_HTTP_SSL environment variable

Instead of configuring the consul client with scheme = http, if not scheme is
provider via the query string, pass an empty scheme.
This allows to configure the scheme via the CONSUL_HTTP_SSL environment
variable, that the consul client parses if no scheme is set.

Author: Fabian Holler

README.md

@@ -25,7 +25,7 @@ The default for `<consul-server>` is `127.0.0.1:8500`.
 
 | OPT        | Format                          | Default  | Description                                                                                                                                                      |
 |------------|---------------------------------|----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| scheme     | `http\|https`                   | http     | Establish connection to consul via http or https.                                                                                                                |
+| scheme     | `http\|https`                   |          | Establish connection to consul via http or https.                                                                                                                |
 | tags       | `<tag>,[,<tag>]...`             |          | Filter service by tags                                                                                                                                           |
 | health     | `healthy\|fallbackToUnhealthy`  | healthy  | `healthy` resolves only to services with a passing health status.<br>`fallbackToUnhealthy` resolves to unhealthy ones if none exist with passing healthy status. |
 | token      | `string`                        |          | Authenticate Consul API Request with the token.                                                                                                                  |

consul/builder.go

@@ -16,7 +16,7 @@
 // OPT is one of:
 //
 //   - scheme=http|https specifies if the connection to Consul is established
-//     via HTTP or HTTPS. Default: http
+//     via HTTP or HTTPS.
 //   - tags=<tag>[,<tag>]... only resolves to instances that have the given
 //     tags. Default: empty
 //   - health=healthy|fallbackToUnhealthy filters Services by their health status.
@@ -88,7 +88,6 @@ func extractOpts(opts url.Values) (scheme string, tags []string, health healthFi
 }
 
 func parseEndpoint(url *url.URL) (serviceName, scheme string, tags []string, health healthFilter, token string, err error) {
-	const defScheme = "http"
 	const defHealthFilter = healthFilterOnlyHealthy
 
 	// url.Path contains a leading "/", when the URL is in the form
@@ -103,10 +102,6 @@ func parseEndpoint(url *url.URL) (serviceName, scheme string, tags []string, hea
 		return "", "", nil, health, "", err
 	}
 
-	if scheme == "" {
-		scheme = defScheme
-	}
-
 	if health == healthFilterUndefined {
 		health = defHealthFilter
 	}