From cf998978a8b94db03be98f72f795582e4b920ba9 Mon Sep 17 00:00:00 2001
From: Josh Curl <josh@curl.me>
Date: Thu, 15 Sep 2016 16:12:15 -0700
Subject: [PATCH] Refactor how consoles and engines are loaded

---
 cmd/control/engine.go               |  5 +--
 cmd/switchconsole/switch_console.go |  5 +--
 compose/reload.go                   | 48 ++++++++++++++++++++++++-----
 3 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/cmd/control/engine.go b/cmd/control/engine.go
index 3fa22d25..7e100afc 100644
--- a/cmd/control/engine.go
+++ b/cmd/control/engine.go
@@ -10,7 +10,6 @@ import (
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/codegangsta/cli"
-	composeConfig "github.com/docker/libcompose/config"
 	"github.com/docker/libcompose/project/options"
 	"github.com/rancher/os/compose"
 	"github.com/rancher/os/config"
@@ -68,9 +67,7 @@ func engineSwitch(c *cli.Context) error {
 		log.Fatal(err)
 	}
 
-	project.ServiceConfigs.Add("docker", &composeConfig.ServiceConfig{})
-
-	if err = compose.LoadService(project, cfg, true, newEngine); err != nil {
+	if err = compose.LoadSpecialService(project, cfg, "docker", newEngine); err != nil {
 		log.Fatal(err)
 	}
 
diff --git a/cmd/switchconsole/switch_console.go b/cmd/switchconsole/switch_console.go
index 21905d17..71a45f0c 100644
--- a/cmd/switchconsole/switch_console.go
+++ b/cmd/switchconsole/switch_console.go
@@ -4,7 +4,6 @@ import (
 	"os"
 
 	log "github.com/Sirupsen/logrus"
-	composeConfig "github.com/docker/libcompose/config"
 	"github.com/docker/libcompose/project/options"
 	"github.com/rancher/os/compose"
 	"github.com/rancher/os/config"
@@ -25,9 +24,7 @@ func Main() {
 	}
 
 	if newConsole != "default" {
-		project.ServiceConfigs.Add("console", &composeConfig.ServiceConfig{})
-
-		if err = compose.LoadService(project, cfg, true, newConsole); err != nil {
+		if err = compose.LoadSpecialService(project, cfg, "console", newConsole); err != nil {
 			log.Fatal(err)
 		}
 	}
diff --git a/compose/reload.go b/compose/reload.go
index 8163d4f4..492b3012 100644
--- a/compose/reload.go
+++ b/compose/reload.go
@@ -37,6 +37,37 @@ func LoadService(p *project.Project, cfg *config.CloudConfig, useNetwork bool, s
 	return nil
 }
 
+func LoadSpecialService(p *project.Project, cfg *config.CloudConfig, serviceName, serviceValue string) error {
+	// Save config in case load fails
+	previousConfig, ok := p.ServiceConfigs.Get(serviceName)
+
+	p.ServiceConfigs.Add(serviceName, &composeConfig.ServiceConfig{})
+
+	if err := LoadService(p, cfg, true, serviceValue); err != nil {
+		// Rollback to previous config
+		if ok {
+			p.ServiceConfigs.Add(serviceName, previousConfig)
+		}
+		return err
+	}
+
+	return nil
+}
+
+func loadConsoleService(cfg *config.CloudConfig, p *project.Project) error {
+	if cfg.Rancher.Console == "" || cfg.Rancher.Console == "default" {
+		return nil
+	}
+	return LoadSpecialService(p, cfg, "console", cfg.Rancher.Console)
+}
+
+func loadEngineService(cfg *config.CloudConfig, p *project.Project) error {
+	if cfg.Rancher.Docker.Engine == "" || cfg.Rancher.Docker.Engine == cfg.Rancher.Defaults.Docker.Engine {
+		return nil
+	}
+	return LoadSpecialService(p, cfg, "docker", cfg.Rancher.Docker.Engine)
+}
+
 func projectReload(p *project.Project, useNetwork *bool, loadConsole bool, environmentLookup *docker.ConfigEnvironment, authLookup *docker.ConfigAuthLookup) func() error {
 	enabled := map[interface{}]interface{}{}
 	return func() error {
@@ -62,17 +93,18 @@ func projectReload(p *project.Project, useNetwork *bool, loadConsole bool, envir
 			enabled[service] = service
 		}
 
-		if loadConsole && cfg.Rancher.Console != "" && cfg.Rancher.Console != "default" {
-			if err := LoadService(p, cfg, *useNetwork, cfg.Rancher.Console); err != nil && err != network.ErrNoNetwork {
-				log.Error(err)
+		if !*useNetwork {
+			return nil
+		}
+
+		if loadConsole {
+			if err := loadConsoleService(cfg, p); err != nil {
+				log.Errorf("Failed to load console: %v", err)
 			}
 		}
 
-		if cfg.Rancher.Docker.Engine != "" && cfg.Rancher.Docker.Engine != cfg.Rancher.Defaults.Docker.Engine {
-			p.ServiceConfigs.Add("docker", &composeConfig.ServiceConfig{})
-			if err := LoadService(p, cfg, *useNetwork, cfg.Rancher.Docker.Engine); err != nil && err != network.ErrNoNetwork {
-				log.Error(err)
-			}
+		if err := loadEngineService(cfg, p); err != nil {
+			log.Errorf("Failed to load engine: %v", err)
 		}
 
 		return nil