imagestorage: fix templating of public_url option for webdav (#74885)

* spelling in error message

* imguploader: fix template for webdav url

Since a few years ago, when loading the config file, the  template gets replaced in the expanding
env var phase (see ##25075) and introduced a bug in the webdav public_url config option. This commit
changes the template syntax to be {{file}}. This doesn't get expanded and removed when the config file
is loaded.

* devenv: add a block for a WebDAV server

* Adding alerting as codeowners for webdav

---------

Co-authored-by: Timur Olzhabayev <timur.olzhabayev@grafana.com>

.github/CODEOWNERS

@@ -209,6 +209,7 @@
 /devenv/docker/blocks/tempo/ @grafana/observability-traces-and-profiling
 /devenv/docker/blocks/traefik/ @mckn
 /devenv/docker/blocks/zipkin/ @grafana/observability-traces-and-profiling
+/devenv/docker/blocks/webdav/ @grafana/alerting-backend-product
 /devenv/docker/buildcontainer/ @bergquist
 /devenv/docker/compose_header.yml @grafana/backend-platform
 /devenv/docker/debtest/ @bergquist

devenv/docker/blocks/webdav/README.md

@@ -0,0 +1,26 @@
+# README for the image storage WebDAV docker block
+
+This block is used for testing the [WebDAV](https://grafana.com/docs/grafana/latest/setup-grafana/configure-grafana/#external_image_storagewebdav) option for external image storage which is used in [alert notifications](https://grafana.com/docs/grafana/latest/alerting/manage-notifications/images-in-notifications/). This uses the simplest WebDav server that is still being maintained, a project called [Dufs](https://github.com/sigoden/dufs).
+
+## Using Dufs
+
+Dufs has a web UI that can be accessed at http://localhost:5000 to easily see which files have been uploaded by Grafana. The config has disabled authentication and allows everyone to read and write files.
+
+## Configuring image storage in Grafana to use Dufs
+
+An example config for external image storage with webdav enabled:
+
+```ini
+[external_image_storage]
+provider = webdav
+
+[external_image_storage.webdav]
+url = http://127.0.0.1:5000/images
+public_url = http://127.0.0.1:5000/images/{{file}}
+
+; as auth is not configured in Dufs, these are just dummy values
+username = test
+password = test
+```
+
+Note: As everything runs on localhost, the image in an email notification will be broken but the link will work if you click on it and open it in your browser.

devenv/docker/blocks/webdav/docker-compose.yaml

@@ -0,0 +1,10 @@
+  webdav:
+    image: sigoden/dufs
+    ports:
+      - "5000:5000"
+    volumes:
+      - "webdav-data:/data"
+    command: "/data -A"
+
+volumes:
+  webdav-data: {}

docs/sources/setup-grafana/configure-grafana/_index.md

@@ -1983,7 +1983,7 @@ Basic auth password.
 
 ### public_url
 
-Optional URL to send to users in notifications. If the string contains the sequence `${file}`, it is replaced with the uploaded filename. Otherwise, the file name is appended to the path part of the URL, leaving any query string unchanged.
+Optional URL to send to users in notifications. If the string contains the sequence `{{file}}`, it is replaced with the uploaded filename. Otherwise, the file name is appended to the path part of the URL, leaving any query string unchanged.
 
 <hr>
 

pkg/components/imguploader/webdavuploader.go

@@ -37,8 +37,8 @@ var netClient = &http.Client{
 }
 
 func (u *WebdavUploader) PublicURL(filename string) string {
-	if strings.Contains(u.public_url, "${file}") {
-		return strings.ReplaceAll(u.public_url, "${file}", filename)
+	if strings.Contains(u.public_url, "{{file}}") {
+		return strings.ReplaceAll(u.public_url, "{{file}}", filename)
 	}
 
 	publicURL, _ := url.Parse(u.public_url)

pkg/components/imguploader/webdavuploader_test.go

@@ -2,10 +2,10 @@ package imguploader
 
 import (
 	"context"
-	"net/url"
 	"strings"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -35,11 +35,10 @@ func TestUploadToWebdav(t *testing.T) {
 func TestPublicURL(t *testing.T) {
 	t.Run("Given a public URL with parameters, and no template", func(t *testing.T) {
 		webdavUploader, _ := NewWebdavImageUploader("http://localhost:8888/webdav/", "test", "test", "http://cloudycloud.me/s/DOIFDOMV/download?files=")
-		parsed, _ := url.Parse(webdavUploader.PublicURL("fileyfile.png"))
-		require.True(t, strings.HasSuffix(parsed.Path, "fileyfile.png"))
+		assert.Equal(t, "http://cloudycloud.me/s/DOIFDOMV/download/fileyfile.png?files=", webdavUploader.PublicURL("fileyfile.png"))
 	})
 	t.Run("Given a public URL with parameters, and a template", func(t *testing.T) {
-		webdavUploader, _ := NewWebdavImageUploader("http://localhost:8888/webdav/", "test", "test", "http://cloudycloud.me/s/DOIFDOMV/download?files=${file}")
-		require.True(t, strings.HasSuffix(webdavUploader.PublicURL("fileyfile.png"), "fileyfile.png"))
+		webdavUploader, _ := NewWebdavImageUploader("http://localhost:8888/webdav/", "test", "test", "http://cloudycloud.me/s/DOIFDOMV/download?files={{file}}")
+		assert.Equal(t, "http://cloudycloud.me/s/DOIFDOMV/download?files=fileyfile.png", webdavUploader.PublicURL("fileyfile.png"))
 	})
 }

pkg/setting/expanders.go

@@ -57,7 +57,7 @@ func expandConfig(file *ini.File) error {
 	for _, expander := range expanders {
 		err := expander.expander.SetupExpander(file)
 		if err != nil {
-			return fmt.Errorf("got error during initilazation of expander '%s': %w", expander.name, err)
+			return fmt.Errorf("got error during initialization of expander '%s': %w", expander.name, err)
 		}
 
 		for _, section := range file.Sections() {