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dokku

Dokku: Error 521 when trying to view the Ruby demo app

I'm trying to learn Dokku and following the "Deploying an Application" tutorial, using their ruby-getting-started example project.

I've run git push dokku main without issues, and added an A record in Cloudflare to point from the ruby-getting-started subdomain to the IP address of the droplet.

When I visit the URL, I get Cloudflare's "Web Host is down" / 521 error screen.

Dokku's logs don't seem to show any access records or other errors. It's as if it's not receiving the request.

Solution

  • After lots of Googling, it turned out it was because my $5/mo 1-GB-of-RAM Digital Ocean droplet didn't have enough RAM to build the Ruby on Rails demo app.