FAQ / troubleshooting

Frequently asked questions for administering the race server.

My server is running but pages are unstyled

This can happen if Webpack has failed. Webpack depends on node.js, and is a pre-processor that bundles all the static assets (JavaScript, images, and — the first thing you notice if it’s not working — CSS (stylesheets)). If you have access to the command line where your server is running, try running npm run build and look for diagnostic/error messages.

I see “There was a problem at start-up” (and code 500)

Check the message that accompanies the warning. There are two distinct kinds of problem — notice which of these two you’re seeing:

• “probably a failure to connect: check DATABASE_URL and error logs”
• “app had unpopulated database (missing table): need to run migrations first, or schema.sql?”

In the first case, check that your DATABASE_URL is correct. If you’re using something like Postgres or mySQL, check that you really can (manually) connect to the database using the authorisation criteria you’ve included in the URL. Remember that the username and password here are for the database, and nothing to do with (for example) any passwords or auth codes on the race server.

There are a couple of special config settings which affect the way that DATABASE_URL is used, so if you’re sure the username and password you’ve provided in that string are correct, these might help: see more about database-related environment variables.

You can see examples of what the DATABASE_URL should look like for different kinds of database (including the SQLite one: see note below) by looking inside env.example.

In the second case — where you see the “unpopulated database” message — the connection (and hence DATABASE_URL) is OK but you’ve managed to run the race server before you’ve populated the database. Specifically, the tables the app expected to find in there don’t exist yet. These are usually set up by running Flask’s database migration. You won’t be able to run your set-up phase until you’ve fixed this.

If you’re using Docker or Heroku, the start-up process automatically runs Flask’s database migrations before it launches the webserver, which takes care of this (the migrations make the tables). If that’s not working for you — which is unexpected, so get in touch — there will be failure messages in the build or release logs that should help with diagnosis.

You can explicitly run the database migrations using:

 flask db upgrade

If you can’t run the Flask database schema migrations, but you know your way around SQL, then there’s a schema.sql in the server repo that you can use to populate the database manually instead.

An extra tip: if you’re having database problems, one thing to try is switching your DATABASE_URL to use SQLite — just as a test — and see if you get the same problem. This can be handy because SQLite doesn’t use any authorisation credentials, which is why that’s a good smoke test: you can’t get a password or username wrong.

Server responds to every request with unknown key error (and code 500)

This used to be the behaviour of the server if the database connection was missing at start-up — we’ve since changed this, so now you get the more informative warning described above. If you’re still seeing this message then maybe the database connection has gone down while the app has been running. Try restarting the database, check it’s running, and that the connection criteria in your DATABASE_URL setting still work. Once you know the database is good again, restart the race server.

Error: Could not locate a Flask application

If you see this error and you’re trying to launch the app — or the database migrations — from the command line, then perhaps your FLASK_APP environment variable is wrong (maybe from another project entirely?), you haven’t set one at all, or you’re trying to launch from the “wrong” directory.

First, cd to the directory that contains the application files and try again.

If that doesn’t work, then the error message probably goes on to suggest setting FLASK_APP or using the --app option. How you do that depends a little which platform you’re on: see set or export env variables. Provided you are in the right directory (because the values here are relative), either one of these values should work: autoapp.py or buggy_race_server/app.py.

Can I delete a user?

Yes, and if you delete a user their buggy and task texts will be deleted too. If you delete a user, you can’t get them back, so only do it if you’re sure you don’t want their data (for example, if they were added by mistake). See Deleting a user.

If you want to suspend a user, you can mark them as inactive, which is like deletion without destroying the data. Go to Admin → Users, pick the user and Edit. For Is active?, select No. This hides the user and also prevents them logging in. Inactive users’ buggies are excluded from race files: when you download a race file for a race, only buggies belonging to active users are included.

You can also disable a user’s login if you just want to prevent them logging in or changing anything on the server.

I’ve forgotten the authorisation code

You can reset this by setting it as an environment variable and restarting the race server. You should then remove the environment declaration (because the value you’ve just set is now saved in the database).

I’ve forgotten my password and can’t log in

An administrator who knows the authorisation code can set any user’s password (typically you do that and then invite the user to change it to one only they know as soon as they’ve got back in). Note the authorisation code is needed to change another admin user’s password.

If you’re a Teaching Assistant, you may be able to reset students’ passwords (if the config setting IS_TA_PASSWORD_CHANGE_ENABLED is Yes).

If nobody can log in as an administrator, see I’ve accidentally demoted/deactivated the only admin account.

Change passwords by going to Admin → Users → Change passwords.

I’ve accidentally demoted/deactivated the only admin account

Set the environment variable IS_PUBLIC_REGISTRATION_ALLOWED to 1 (true). Restart the server and go to /admin/users/new. Create a new admin user with a known password. You’ll need the current authentication code. If you’ve lost that too, then set a new one as an environment variable too: AUTHORISATION_CODE.

Once you’ve got a new admin user, log in with the new credentials. Go to Admin → Config → Server and set IS_PUBLIC_REGISTRATION_ALLOWED back to No. Remove the environment variable setting you used to bypass that (do not forget this step: otherwise, you’ll have public registration again next time you restart). Promote or register the user that was lost — and once you’ve done that, maybe deactivate or delete the new one.

Oops! An announcement with bad HTML is breaking every page

Announcements are uniquely dangerous because if you accidentally fail to “balance your tags” they can have a destructive effect on page layout (including the pages for fixing it). You can resolve this by editing the announcement to remove the offending HTML. Specifically, you can disable the HTML to get to the edit-announcements pages.

Why can’t I replay this race?

If you are looking at a race on the server and you can’t see a Replay button, it may be because the race hasn’t been run yet (no results have been uploaded) or the race still has the results hidden from students (go to Admin → Races → Race:Details Edit, and fix Are results visible?). If it’s neither of those, check that there is a URL for race_file_url (described as “URL of race file (JSON)”). If there’s no race file URL to replay, the server won’t show the Replay button.

If the Replay button is there but the problem is that the race won’t run — if it says there are no events, for example — then maybe you’ve uploaded the wrong race file. It must be a race file with events in it for the player to show them. See running races for more information.

The route of a race is defined by the path inside an SVG file: if that won’t load, the race can’t be replayed. If that’s the problem, see Racetrack not working: “Problem getting SVG”.

I made a task text but it’s not showing up! Where is it?

You can access you own task texts by clicking on Settings → List your task texts. This is where you can find all the texts you’ve made, as well as editing (or even deleting) them.

If you’re not an enrolled student (for example, you’re a Teaching Assistant or admin) then your texts will not appear on the main text matrix. That only shows the texts for active (that is, not suspended) students.

This is why, while you’re setting up the course, it’s OK to set staff users to also be “enrolled students”, so you can experiment with things like this and see how it looks. Just remember to edit the user to remove enrolled student status from any staff accounts before the course starts.

Note that task texts can be disabled entirely by setting IS_STORING_STUDENT_TASK_TEXTS to No: see the ‘Tasks’ config settings.

What’s the difference between an external ID and an external username?

Very little — both are optional settings (with string values) that you can save with each of your users if that’s helpful. We used both at Royal Holloway because students had both a college username (which we were using for the more complex VSCode distribution method) and an underlying Moodle ID which helped us when doing our assessments/marking.

You can enable either or both of these, together with giving them descriptive names and example values, via the “Users” group of config settings.

Racetrack not working: “Problem getting SVG”

If you look at a race or a racetrack as an admin and you see “Problem getting SVG”, there are a couple of things to check. If you have this problem, it probably means the race won’t replay on the race player either.

First, try hitting the racetrack SVG’s URL in the browser (view either the race or the racetrack in the admin): you should not get a 404. If you do, then either the URL is wrong, or the SVG file has been deleted since the URL was added.

If it’s not that, the other reason might be a CORS problem. This can happen if the SVG is coming from a different domain than your race server. If that’s the case, look in your browser’s console for messages such as Cross-Origin Request Blocked. If that’s what you see, you need to either modify the server that’s sending the SVG file to send the correct CORS headers or, if you can’t do that, host it on a server that does. SVG files served from GitHub Pages sites have wildcarded CORS headers, so those should work. The most certain way to avoid CORS problems is to serve the SVG file from the same domain as the requester — in this context, that’s almost certainly the race server whose race player you are running. If you’re hosting your own race server consider adding static files such as the racetrack SVG to the repo you’ve forked. Look in buggy_race_server/race/assets/tracks to see the race server’s default racetracks, and add your own alongside those. You can access them on your server at /races/assets/tracks/filename.svg. Note that racetrack assets like this are treated differently from general static content (such as images or CSS) because they are not handled by Webpack.

How can I find out what version I’m running?

Go to Admin → Dashboard → System info where it’s at the top of the page.
Or look under the hamster on the /about page.