MM-57013 Added download button for downloading logs from server logs page in system console (#26389)

* added download system logs

* download all logs

* download all logs check-lint fix

* check lint fix

* download logs api

* download logs api working

* download logs working with error log

* linting issues and code cleanup

* CI check fix

* documented the api and logs from file with error handling

* test and final changes done

* final changes done

* Fix order of server-side translations

* Fix incorrect indentation of logs.yaml

---------

Co-authored-by: Harrison Healey <harrisonmhealey@gmail.com>

server/channels/api4/system.go

@@ -50,6 +50,7 @@ func (api *API) InitSystem() {
 	api.BaseRoutes.APIRoot.Handle("/caches/invalidate", api.APISessionRequired(invalidateCaches)).Methods("POST")
 
 	api.BaseRoutes.APIRoot.Handle("/logs", api.APISessionRequired(getLogs)).Methods("GET")
+	api.BaseRoutes.APIRoot.Handle("/logs/download", api.APISessionRequired(downloadLogs)).Methods("GET")
 	api.BaseRoutes.APIRoot.Handle("/logs/query", api.APISessionRequired(queryLogs)).Methods("POST")
 	api.BaseRoutes.APIRoot.Handle("/logs", api.APIHandler(postLog)).Methods("POST")
 
@@ -414,6 +415,36 @@ func getLogs(c *Context, w http.ResponseWriter, r *http.Request) {
 	w.Write([]byte(model.ArrayToJSON(lines)))
 }
 
+func downloadLogs(c *Context, w http.ResponseWriter, r *http.Request) {
+	auditRec := c.MakeAuditRecord("downloadLogs", audit.Fail)
+	defer c.LogAuditRec(auditRec)
+	if *c.App.Config().ExperimentalSettings.RestrictSystemAdmin {
+		c.Err = model.NewAppError("downloadLogs", "api.restricted_system_admin", nil, "", http.StatusForbidden)
+		return
+	}
+	if !c.App.SessionHasPermissionTo(*c.AppContext.Session(), model.PermissionGetLogs) {
+		c.SetPermissionError(model.PermissionGetLogs)
+		return
+	}
+
+	fileData, err := c.App.GetMattermostLog(c.AppContext)
+	if err != nil {
+		c.Err = model.NewAppError("downloadLogs", "api.system.logs.download_bytes_buffer.app_error", nil, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	reader := bytes.NewReader(fileData.Body)
+	web.WriteFileResponse("mattermost.log",
+		"text/plain",
+		int64(len(fileData.Body)),
+		time.Now(),
+		*c.App.Config().ServiceSettings.WebserverMode,
+		reader,
+		true,
+		w,
+		r)
+}
+
 func postLog(c *Context, w http.ResponseWriter, r *http.Request) {
 	forceToDebug := false