If asked via a CLI flag in the pusher call, delete dashboards which files were removed

README.md

 
 It will then call the puller to have all the files up to date. This is mainly done to update the version number of each dashboard, as Grafana updates them automatically when a new or updated dashboard is pushed.
 
-Please note that the pusher currently only pushes new or modified dashboards to the Grafana API. If the file for a dashboard is removed from the Git repository, the dashboard won't be deleted on the Grafana instance.
+Please note that the pusher currently only pushes new or modified dashboards to the Grafana API. If the file for a dashboard is removed from the Git repository, the dashboard won't be deleted on the Grafana instance, unless specifically asked (see below for more details).
 
 Because it hosts a webserver, the pusher runs as a daemon and never exists unless it `panic`s because of an error, or it is killed (e.g. with `Ctrl+C`).
 
 
 If the `--config` flag isn't present in the command line call, it will default to a `config.yaml` file located in the directory from where the call is made.
 
+The pusher can also be called with the `--delete-removed` flag which will allows it to check for dashboards which files were removed from the Git repository and delete them from Grafana.
+
 ## Configure
 
 To run either the puller or the pusher, you will need a configuration file first. The simplest way to create one is to copy the `config.example.yaml` file at the root of this repository and replace all of the placeholder values with your own.

src/grafana/dashboards.go

 
 	return
 }
+
+// DeleteDashboard deletes the dashboard identified by a given slug on the
+// Grafana API.
+// Returns an error if the process failed.
+func (c *Client) DeleteDashboard(slug string) (err error) {
+	_, err = c.request("DELETE", "dashboards/db/"+slug, nil)
+	return
+}

src/pusher/main.go

 	"logger"
 )
 
-// The Grafana API client and the config need to be global to the package since
-// we need them in the webhook handlers.
+// Some variables need to be global to the package since we need them in the
+// webhook handlers.
 // TODO: Find a better way to pass it to the handlers
 var (
 	grafanaClient *grafana.Client
 	cfg           *config.Config
+	deleteRemoved = flag.Bool("delete-removed", false, "For each file removed from Git, delete the corresponding dashboard on the Grafana API")
 )
 
 func main() {

src/pusher/webhook.go

 		return
 	}
 
-	// Files to push are stored in a map before being pushed to the Grafana API.
-	// We don't push them in the loop iterating over commits because, in the
-	// case a file is successively updated by two commits pushed at the same
-	// time, it would push the same file several time, which isn't an optimised
-	// behaviour.
+	// Files to push and their contents are stored in a map before being pushed
+	// to the Grafana API. We don't push them in the loop iterating over commits
+	// because, in the case a file is successively updated by two commits pushed
+	// at the same time, it would push the same file several time, which isn't
+	// an optimised behaviour.
 	filesToPush := make(map[string][]byte)
 
 	// Iterate over the commits descriptions from the payload
 			}
 		}
 
-		// TODO: Remove a dashboard when its file gets deleted?
+		// If a file describing a dashboard gets removed from the Git repository,
+		// delete the corresponding dashboard on Grafana, but only if the user
+		// mentionned they want to do so with the correct command line flag.
+		if *deleteRemoved {
+			for _, removedFile := range commit.Removed {
+				if err = deleteDashboard(removedFile); err != nil {
+					logrus.WithFields(logrus.Fields{
+						"error":    err,
+						"filename": removedFile,
+					}).Error("Failed to delete the dashboard")
+				}
+
+				continue
+			}
+		}
 	}
 
 	// Push all files to the Grafana API
 	return
 }
 
+// deleteDashboard reads the dashboard described in a given file and, if the file
+// isn't set to be ignored, delete the corresponding dashboard from Grafana.
+// Returns an error if there was an issue reading the file's content, checking
+// if the dashboard is to be ignored, computing its slug or deleting it from
+// Grafana.
+func deleteDashboard(filename string) (err error) {
+	// Don't delete versions.json
+	if strings.HasSuffix(filename, "versions.json") {
+		return
+	}
+
+	// Read the file's content
+	fileContent, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return
+	}
+
+	// Check if dashboard is ignored
+	ignored, err := isIgnored(fileContent)
+	if err != nil {
+		return
+	}
+
+	if !ignored {
+		// Retrieve dashboard slug because we need it in the deletion request.
+		var slug string
+		slug, err = helpers.GetDashboardSlug(fileContent)
+		if err != nil {
+			return
+		}
+
+		// Delete the dashboard
+		err = grafanaClient.DeleteDashboard(slug)
+	}
+
+	return
+}
+
 // isIgnored checks whether the file must be ignored, by checking if there's an
 // prefix for ignored files set in the configuration file, and if the dashboard
 // described in the file has a name that starts with this prefix. Returns an