Automatic Port Numbers (#105)

Add automatic port numbers assignment in configuration file. The string `${PORT}` will be substituted in model.cmd and model.proxy for an actual port number. This also allows model.proxy to be omitted from the configuration.

proxy/config_test.go

@@ -44,6 +44,7 @@ models:
     checkEndpoint: "/"
   model4:
     cmd: path/to/cmd --arg1 one
+    proxy: "http://localhost:8082"
     checkEndpoint: "/"
 
 healthCheckTimeout: 15
@@ -74,6 +75,7 @@ groups:
 	}
 
 	expected := Config{
+		StartPort: 5800,
 		Models: map[string]ModelConfig{
 			"model1": {
 				Cmd:           "path/to/cmd --arg1 one",
@@ -98,6 +100,7 @@ groups:
 			},
 			"model4": {
 				Cmd:           "path/to/cmd --arg1 one",
+				Proxy:         "http://localhost:8082",
 				CheckEndpoint: "/",
 			},
 		},
@@ -166,8 +169,9 @@ groups:
 `
 	// Load the config and verify
 	_, err := LoadConfigFromReader(strings.NewReader(content))
-	assert.Equal(t, "model member model2 is used in multiple groups: group1 and group2", err.Error())
 
+	// a Contains as order of the map is not guaranteed
+	assert.Contains(t, err.Error(), "model member model2 is used in multiple groups:")
 }
 
 func TestConfig_ModelAliasesAreUnique(t *testing.T) {
@@ -186,10 +190,12 @@ models:
       - m1
       - m2
 `
-
 	// Load the config and verify
 	_, err := LoadConfigFromReader(strings.NewReader(content))
-	assert.Equal(t, "duplicate alias m1 found in model: model2", err.Error())
+
+	// this is a contains because it could be `model1` or `model2` depending on the order
+	// go decided on the order of the map
+	assert.Contains(t, err.Error(), "duplicate alias m1 found in model: model")
 }
 
 func TestConfig_ModelConfigSanitizedCommand(t *testing.T) {
@@ -279,3 +285,77 @@ func TestConfig_SanitizeCommand(t *testing.T) {
 	assert.Error(t, err)
 	assert.Nil(t, args)
 }
+
+func TestConfig_AutomaticPortAssignments(t *testing.T) {
+
+	t.Run("Default Port Ranges", func(t *testing.T) {
+		content := ``
+		config, err := LoadConfigFromReader(strings.NewReader(content))
+		if !assert.NoError(t, err) {
+			t.Fatalf("Failed to load config: %v", err)
+		}
+
+		assert.Equal(t, 5800, config.StartPort)
+	})
+	t.Run("User specific port ranges", func(t *testing.T) {
+		content := `startPort: 1000`
+		config, err := LoadConfigFromReader(strings.NewReader(content))
+		if !assert.NoError(t, err) {
+			t.Fatalf("Failed to load config: %v", err)
+		}
+
+		assert.Equal(t, 1000, config.StartPort)
+	})
+
+	t.Run("Invalid start port", func(t *testing.T) {
+		content := `startPort: abcd`
+		_, err := LoadConfigFromReader(strings.NewReader(content))
+		assert.NotNil(t, err)
+	})
+
+	t.Run("start port must be greater than 1", func(t *testing.T) {
+		content := `startPort: -99`
+		_, err := LoadConfigFromReader(strings.NewReader(content))
+		assert.NotNil(t, err)
+	})
+
+	t.Run("Automatic port assignments", func(t *testing.T) {
+		content := `
+startPort: 5800
+models:
+  model1:
+    cmd: svr --port ${PORT}
+  model2:
+    cmd: svr --port ${PORT}
+    proxy: "http://172.11.22.33:${PORT}"
+  model3:
+    cmd: svr --port 1999
+    proxy: "http://1.2.3.4:1999"
+`
+		config, err := LoadConfigFromReader(strings.NewReader(content))
+		if !assert.NoError(t, err) {
+			t.Fatalf("Failed to load config: %v", err)
+		}
+
+		assert.Equal(t, 5800, config.StartPort)
+		assert.Equal(t, "svr --port 5800", config.Models["model1"].Cmd)
+		assert.Equal(t, "http://localhost:5800", config.Models["model1"].Proxy)
+
+		assert.Equal(t, "svr --port 5801", config.Models["model2"].Cmd)
+		assert.Equal(t, "http://172.11.22.33:5801", config.Models["model2"].Proxy)
+
+		assert.Equal(t, "svr --port 1999", config.Models["model3"].Cmd)
+		assert.Equal(t, "http://1.2.3.4:1999", config.Models["model3"].Proxy)
+
+	})
+
+	t.Run("Proxy value required if no ${PORT} in cmd", func(t *testing.T) {
+		content := `
+models:
+  model1:
+    cmd: svr --port 111
+`
+		_, err := LoadConfigFromReader(strings.NewReader(content))
+		assert.Equal(t, "model model1 requires a proxy value when not using automatic ${PORT}", err.Error())
+	})
+}