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Debugging at Mattermost

Debugging in the Main Process 

The simplest way to debug the main process is to simply insert logging statements wherever needed and have the application output logs of whatever is necessary.

If you’d like to make use of better debugging tools, you can use the Chrome Dev Tools or the debugger in VSCode by following the steps here:

Debugging in the Renderer Process 

The renderer processes are controller by Chrome instances, so each of them will have their own Developer Tools instance.

You can access these instances by going to the View menu (under the 3-dot menu on Windows/Linux, and in the top bar on macOS) and selecting:

  • Developer Tools for Application Wrapper for anything involving the top bar.
  • Developer Tools for Current Tab for anything involving the Mattermost view or the preload script.
    • Note: For this one, make sure you’re currently on the tab where you want to load the Developer Tools. You can have instances open for tabs you aren’t currently viewing, but to open them in the first place requires it to be opened.

There are other BrowserViews that are governed seperately from the main application wrapper, including:

  • Dropdown Menu
    • You can open this one by adding a line in the main/teamDropdownView.ts file. In the constructor, at the end, add:
      this.view.webContents.openDevTools({mode: 'detach'});
  • Modals
    • You can open these by setting an environment variable when running the Desktop App called MM_DEBUG_MODALS.
      // macOS/Linux
      export MM_DEBUG_MODALS=1
      // Windows PowerShell
      $env:MM_DEBUG_MODALS = 1
  • URL View
    • You can open this one by adding a line in the main/viewManager.ts file. In the function showURLView, at the end, add:
      urlView.webContents.openDevTools({mode: 'detach'});
    • Note: This view is ephemeral and based on whether a link is hovered with the mouse, so it might be best to use some logging instead here.

Debugging the Mattermost Server/Webapp 

Some issues are only reproducible on the Desktop App, though the code that is causing the issue may not live in the Desktop App.

Here are some ways of determining whether this is true:

  • Does the issue reproduce on the browser? Specifically Chrome?
  • Does the issue surround a piece of code on the server/webapp that only applies to the Desktop App? You can check this by seeing if there is a call to isDesktopApp in the webapp.

If you have determined that the issue doesn’t apply to the Desktop App code base directly, you can file a ticket in the appropriate repository, such as the server or webapp repository.

If you are having trouble determining where the issue lies, feel free to post in the Developers: Desktop App on Mattermost Community, or you can file a ticket in the server repository and it will be triaged and transferred to the appropriate location.