Provide a FileSystemLogger in the framework

[luettmaSICKAG]

Currently the logs of a Theia application are only printed to the console.
The "@theia/plugin-ext" extension creates a log directory for each session in $CONFIG_DIR/logs/{TIMESTAMP}.
This seems to be used solely for Theia plugins/VSCode extension (vscode.ExtensionContext.logUri);

We created our own FileSystem logger which writes to $CONFIG_DIR/logs/application-{TIMESTAMP}.log.
The problem here is that we couldn't get the path to the logdir of the current session, because the timestamp is created on the fly and not exposed.

Feature Description:

It would be a great core feature if Theia provided a default implementation of a Logger that stores the messages on the file system.
Either by providing a default implementation or configuration.

[vince-fugnitto]

@luettmaSICKAG thank you for the issue 👍

The problem here is that we couldn't get the path to the logdir of the current session, because the timestamp is created on the fly and not exposed.

I'm not sure I follow as to why moving this logger to the framework would fix the problem, rather this seems to be an issue with the custom implementation included in your application?

[luettmaSICKAG]

I'm not sure I follow as to why moving this logger to the framework would fix the problem, rather this seems to be an issue with the custom implementation included in your application?

The problem was actually that there is no constant / variable exposed that points to the log directory.
The best I could do was to get the CONFIG_DIR and by implicit knowledge the "logs" directory.

@theia/plugin-ext creates a subfolder for the session using a timestamp. I though it'd make sense to store the application log and plugin logs in that "session directory".

Right now this logs directory is only created for plugins.

theia/packages/plugin-ext/src/main/node/paths/plugin-paths-service.ts

Line 53 in 7d3b1d3

const pluginDirPath = path.join(parentLogsDir, this.generateTimeFolderName(), 'host');

The problems are:

• A custom logger extension should not require a dependency to @theia/plugin-ext to get the log path
• Even if we used PluginPathsService.getHostLogPath() it would create a new path

Anyway, it was just a very quick implementation on our side, since we hoped that the logging mechanisms (including log rotation etc) would make it to the framework.