Add scale_from_zero flag

Added scale_from_zero to config, docs and wrote unit test for the
value.

Signed-off-by: Alex Ellis (VMware) <alexellis2@gmail.com>

gateway/README.md

@@ -56,3 +56,4 @@ The gateway can be configured through the following environment variables:
 | `direct_functions_suffix`     | Provide a DNS suffix for invoking functions directly over overlay network  |
 | `basic_auth`              | Set to `true` or `false` to enable embedded basic auth on the /system and /ui endpoints (recommended) |
 | `secret_mount_path`       | Set a location where you have mounted `basic-auth-user` and `basic-auth-password`, default: `/run/secrets/`. |
+| `scale_from_zero`       | Enables an intercepting proxy which will scale any function from 0 replicas to the desired amount |

gateway/types/readconfig.go

@@ -112,6 +112,7 @@ func (ReadConfig) Read(hasEnv HasEnv) GatewayConfig {
 		secretPath = "/run/secrets/"
 	}
 	cfg.SecretMountPath = secretPath
+	cfg.ScaleFromZero = parseBoolValue(hasEnv.Getenv("scale_from_zero"))
 
 	return cfg
 }
@@ -149,11 +150,16 @@ type GatewayConfig struct {
 	// If set this will be used to resolve functions directly
 	DirectFunctionsSuffix string
 
+<<<<<<< HEAD
 	// If set, reads secrets from file-system for enabling basic auth.
 	UseBasicAuth bool
 
 	// SecretMountPath specifies where to read secrets from for embedded basic auth
 	SecretMountPath string
+=======
+	// Enable the gateway to scale any service from 0 replicas to its configured "min replicas"
+	ScaleFromZero bool
+>>>>>>> Add scale_from_zero flag
 }
 
 // UseNATS Use NATSor not

gateway/types/readconfig_test.go

@@ -68,6 +68,29 @@ func TestRead_DirectFunctionsOverride(t *testing.T) {
 	}
 }
 
+func TestRead_ScaleZeroDefaultAndOverride(t *testing.T) {
+	defaults := NewEnvBucket()
+	readConfig := ReadConfig{}
+	// defaults.Setenv("scale_from_zero", "true")
+	config := readConfig.Read(defaults)
+
+	want := false
+	if config.ScaleFromZero != want {
+		t.Logf("ScaleFromZero should be %v, got: %v", want, config.ScaleFromZero)
+		t.Fail()
+	}
+
+	defaults.Setenv("scale_from_zero", "true")
+	config = readConfig.Read(defaults)
+	want = true
+
+	if config.ScaleFromZero != want {
+		t.Logf("ScaleFromZero was overriden - should be %v, got: %v", want, config.ScaleFromZero)
+		t.Fail()
+	}
+
+}
+
 func TestRead_EmptyTimeoutConfig(t *testing.T) {
 	defaults := NewEnvBucket()
 	readConfig := ReadConfig{}