feat: add custom loading page (#15)

* add option for custom loading and error pages
* document custom landing pages
* link to example templates
* update loading page template to match template actually in-use

README.md

@@ -23,18 +23,26 @@ Traefik middleware to start containers on demand.
 
 ### Plugin configuration
 
+**Custom loading/error pages**
+The `loadingpage` and `errorpage` keys in the plugin configuration can be used to override the default loading and error pages. The value should be a path where a template that can be parsed by Go's [html/template](https://pkg.go.dev/html/template) package can be found in the Traefik container. An example of both a loading page and an error page template can be found in the [pkg/pages/](pkg/pages/) directory in [loading.html](pkg/pages/loading.html) and [error.html](pkg/pages/error.html) respectively. The plugin will default to the built-in loading and error pages if these fields are omitted.
+
+**Example Configuration**
 ```yml
 testData:
   serviceUrl: http://ondemand:10000
   name: TRAEFIK_HACKATHON_whoami
   timeout: 1m
+  loadingpage: /opt/on-demand/loading.html
+  errorpage: /opt/on-demand/error.html
 ```
 
-| Parameter    | Type            | Example                    | Description                                                             |
-| ------------ | --------------- | -------------------------- | ----------------------------------------------------------------------- |
-| `serviceUrl` | `string`        | `http://ondemand:10000`    | The docker container name, or the swarm service name                    |
-| `name`       | `string`        | `TRAEFIK_HACKATHON_whoami` | The container/service to be stopped (docker ps                          | docker service ls) |
-| `timeout`    | `time.Duration` | `1m30s`                    | The duration after which the container/service will be scaled down to 0 |
+| Parameter    | Type            | Example                       | Description                                                             |
+| ------------ | --------------- | --------------------------    | ----------------------------------------------------------------------- |
+| `serviceUrl` | `string`        | `http://ondemand:10000`       | The docker container name, or the swarm service name                    |
+| `name`       | `string`        | `TRAEFIK_HACKATHON_whoami`    | The container/service to be stopped (docker ps                          | docker service ls) |
+| `timeout`    | `time.Duration` | `1m30s`                       | The duration after which the container/service will be scaled down to 0 |
+| `loadingpage`| `string`        | `/opt/on-demand/loading.html` | The path in the traefik container for the loading page template         |
+| `errorpage`  | `string`        | `/opt/on-demand/error.html`   | The path in the traefik container for the error page template           |
 
 ### Traefik-Ondemand-Service
 

ondemand.go

@@ -19,9 +19,11 @@ var netClient = &http.Client{
 
 // Config the plugin configuration
 type Config struct {
-	Name       string `yaml:"name"`
-	ServiceUrl string `yaml:"serviceurl"`
-	Timeout    string `yaml:"timeout"`
+	Name        string `yaml:"name"`
+	ServiceUrl  string `yaml:"serviceurl"`
+	Timeout     string `yaml:"timeout"`
+	ErrorPage   string `yaml:"errorpage"`
+	LoadingPage string `yaml:"loadingpage"`
 }
 
 // CreateConfig creates a config with its default values
@@ -33,10 +35,12 @@ func CreateConfig() *Config {
 
 // Ondemand holds the request for the on demand service
 type Ondemand struct {
-	request string
-	name    string
-	next    http.Handler
-	timeout time.Duration
+	request     string
+	name        string
+	next        http.Handler
+	timeout     time.Duration
+	errorpage   string
+	loadingpage string
 }
 
 func buildRequest(url string, name string, timeout time.Duration) (string, error) {
@@ -67,10 +71,12 @@ func New(ctx context.Context, next http.Handler, config *Config, name string) (h
 	}
 
 	return &Ondemand{
-		next:    next,
-		name:    config.Name,
-		request: request,
-		timeout: timeout,
+		next:        next,
+		name:        config.Name,
+		request:     request,
+		timeout:     timeout,
+		errorpage:   config.ErrorPage,
+		loadingpage: config.LoadingPage,
 	}, nil
 }
 
@@ -83,7 +89,7 @@ func (e *Ondemand) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 
 	if err != nil {
 		rw.WriteHeader(http.StatusInternalServerError)
-		rw.Write([]byte(pages.GetErrorPage(e.name, err.Error())))
+		rw.Write([]byte(pages.GetErrorPage(e.errorpage, e.name, err.Error())))
 	}
 
 	if status == "started" {
@@ -93,11 +99,11 @@ func (e *Ondemand) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	} else if status == "starting" {
 		// Service starting, notify client
 		rw.WriteHeader(http.StatusAccepted)
-		rw.Write([]byte(pages.GetLoadingPage(e.name, e.timeout)))
+		rw.Write([]byte(pages.GetLoadingPage(e.loadingpage, e.name, e.timeout)))
 	} else {
 		// Error
 		rw.WriteHeader(http.StatusInternalServerError)
-		rw.Write([]byte(pages.GetErrorPage(e.name, status)))
+		rw.Write([]byte(pages.GetErrorPage(e.errorpage, e.name, status)))
 	}
 }
 

pkg/pages/error.go

@@ -3,6 +3,7 @@ package pages
 import (
 	"bytes"
 	"html/template"
+	"path"
 )
 
 var errorPage = `<!doctype html>
@@ -175,15 +176,26 @@ type ErrorData struct {
 	Error string
 }
 
-func GetErrorPage(name string, e string) string {
-	tpl, err := template.New("error").Parse(errorPage)
+func GetErrorPage(template_path string, name string, e string) string {
+	var tpl *template.Template
+	var err error
+	if template_path != "" {
+		tpl, err = template.New(path.Base(template_path)).ParseFiles(template_path)
+	} else {
+		tpl, err = template.New("loading").Parse(loadingPage)
+	}
 	if err != nil {
 		return err.Error()
 	}
+
 	b := bytes.Buffer{}
-	tpl.Execute(&b, ErrorData{
+	err = tpl.Execute(&b, ErrorData{
 		Name:  name,
 		Error: e,
 	})
+	if err != nil {
+		return err.Error()
+	}
+
 	return b.String()
 }

pkg/pages/loading.go

@@ -2,6 +2,7 @@ package pages
 
 import (
 	"bytes"
+	"path"
 
 	"fmt"
 	"html/template"
@@ -251,16 +252,27 @@ type LoadingData struct {
 	Timeout string
 }
 
-func GetLoadingPage(name string, timeout time.Duration) string {
-	tpl, err := template.New("loading").Parse(loadingPage)
+func GetLoadingPage(template_path string, name string, timeout time.Duration) string {
+	var tpl *template.Template
+	var err error
+	if template_path != "" {
+		tpl, err = template.New(path.Base(template_path)).ParseFiles(template_path)
+	} else {
+		tpl, err = template.New("loading").Parse(loadingPage)
+	}
 	if err != nil {
 		return err.Error()
 	}
+
 	b := bytes.Buffer{}
-	tpl.Execute(&b, LoadingData{
+	err = tpl.Execute(&b, LoadingData{
 		Name:    name,
 		Timeout: humanizeDuration(timeout),
 	})
+	if err != nil {
+		return err.Error()
+	}
+
 	return b.String()
 }
 

pkg/pages/loading.html

@@ -214,7 +214,7 @@
   </header>
 
   <section class="panel">
-    <h2 class="headline" id="headline">{{name}} is loading...</h2>
+    <h2 class="headline" id="headline">{{ .Name }} is loading...</h2>
     <div class="lds-ellipsis"><div></div><div></div><div></div><div></div></div>
 
     <p class="message text" id="message">Your instance is loading, and will be
@@ -222,7 +222,7 @@
 
 
     <div class="support text">
-      Your instance will shutdown automatically after {{duration}} of
+      Your instance will shutdown automatically after {{ .Timeout }} of
       inactivity.
     </div>
   </section>
@@ -233,4 +233,4 @@
   </footer>
 </body>
 
-</html>
+</html>