I saw an article on HN today called Back to basics: Writing an application using Go and PostgreSQL. It is generally great, but makes a common mistake – creating an unnecessary mega-interface that serves no purpose but to make the code harder to read and maintain. I see people doing this all the time, and it’s wrong, so I wrote a very long rant on HN about it. HN said “that comment is too long”, so here’s the comment!

After many years of jrock.us being served over HTTPS, I finally remembered to enable HTTP Strict Transport Security. There was never any reason not to – all traffic to any website or app at jrock.us goes through my reverse proxy, and it’s served with a wildcard *.jrock.us certficiate. If it doesn’t go through my reverse proxy, that’s a bug, and should be fixed.

Several days after making this change, I closed my GMail tab, and typed mail.jrock.us to get it back. Chrome responded with “Connection closed”. Google must be down! But that seems pretty unlikely, so I tried it in curl:

Like many people, I use cert-manager to automatically renew my website’s TLS certificates with Let’s Encrypt. Unlike many people, I don’t use an Ingress controller to get traffic into my cluster, I just have a few instances of Envoy that terminate TLS and route traffic to the appropriate backend. Cert-manager handles the mechanics of certificate renewal very efficiently; it runs a controller loop that checks all my Certificate objects for expiration, and when a certificate is close to expiring, it goes out and renews it. It then updates a Kubernetes Secret with the new key material, and Kubernetes then makes that new data available to pods that have mounted the Secret as a volume. From there, it’s up to the application to notice that some symlinks have moved around and reload the certificate. Up until very recently, Envoy did not bother to check. So at some point, you had to do a rolling restart of the Envoy deployment to pick up the new certificate. Because there is 30 days between when cert-manager renews the certificate and when the old certificate actually expired, this was rarely a problem in practice. If any of your machines went down, or you edited the config file to add a new route, or you upgraded Envoy itself, the pod containing Envoy would restart, pick up the new certificates, and you’d never notice that it wasn’t automatically reloading the certificate.