Assigning a custom subdomain to a Fly app#

I deployed an app to Fly and decided to point a custom subdomain to it.

My fly app is https://datasette-apache-proxy-demo.fly.dev/

I wanted the URL to be https://datasette-apache-proxy-demo.datasette.io/ (see issue #1524).

Relevant documentation: SSL for Custom Domains.

Assign a CNAME#

First step was to add a CNAME to my datasette.io domain.

I pointed CNAME of datasette-apache-proxy-demo.datasette.io at datasette-apache-proxy-demo.fly.dev. using Vercel DNS:

Issuing a certificate#

Fly started serving from http://datasette-apache-proxy-demo.datasette.io/ as soon as the DNS change propagated. To get https:// to work I had to run this:

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% flyctl certs create datasette-apache-proxy-demo.datasette.io
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Your certificate for datasette-apache-proxy-demo.datasette.io is being issued. Status is Awaiting certificates.

I could then run this command periodically to see if it had been issued, which happened about 53 seconds later:

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apache-proxy % flyctl certs show datasette-apache-proxy-demo.datasette.io
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The certificate for datasette-apache-proxy-demo.datasette.io has been issued.
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Hostname                  = datasette-apache-proxy-demo.datasette.io
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DNS Provider              = constellix
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Certificate Authority     = Let's Encrypt
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Issued                    = ecdsa,rsa
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Added to App              = 53 seconds ago
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Source                    = fly