Give group write permissions on nextcloud.log -- and keep them

I notice that permissions to nextcloud.log keep resetting to rw-r-----. I can give write permissions to the group but the perms don’t last. This is most inconvenient during testing with phpunit, which is run by a different user than the webserver, as only the first test passes and the next fails due to insufficient write privileges.

I tried setting the file permissions to rw-rw---- with the webserver stopped but there seems to be some logic that removes group write permissions right on the first file access. I also could not find a likely setting in config.php.

Any clue, anybody?

Suffering from a similar issue locally on my dev instance I have this patch applied:

diff --git a/lib/private/Log/File.php b/lib/private/Log/File.php
index a33667c9b6..472fa6b60e 100644
--- a/lib/private/Log/File.php
+++ b/lib/private/Log/File.php
@@ -80,10 +80,13 @@ class File extends LogDetails implements IWriter, IFileBased {
         * @param int $level
        public function write(string $app, $message, int $level) {
+//             if (strpos($message, 'Failed to open stream: Permission denied at')) {
+//                     return;
+//             }
                $entry = $this->logDetailsAsJSON($app, $message, $level);
                $handle = @fopen($this->logFile, 'a');
                if ($this->logFileMode > 0 && is_file($this->logFile) && (fileperms($this->logFile) & 0777) != $this->logFileMode) {
-                       @chmod($this->logFile, $this->logFileMode);
+//                     @chmod($this->logFile, $this->logFileMode);
                if ($handle) {
                        fwrite($handle, $entry."\n");

@nickvergessen: thanks, that seems a good solution

Meanwhile I helped myself with sudo -u www gmake test

I think it is not a good idea to use a different user for testing. Perhaps other parts of webserver/nextcloud do use different user/group-rights, too. What do you want to test? Webserver/Nextcloud or a test user?

And for security reason: Always use only a copy of the system.

You are probably right, I shall resolve to using sudo.
I am working my way into testing my own app on NC and just want to get it right.