SSL Cert Checker

TL;DR

SSL Cert Checker lets you check the validity for a bunch of endpoints

Problem

Our previous CA software had reached EOL.

So we had to setup a new one and incrementally rollout new certs to application. During transition time two valid certs were used: old certs issued by trhe legacy CA. And new certs issued by the new CA software.

To assist ensuring all apps have valid certs i designed a small tool. This tool enabled us to see which apps already use new certs and which ones need attention.

Challenge

The number of involved certs and applications using them was humongous.

Every service and application was documented in excel.

My task was checking every https endpoint for valid certs:

• It had to be issued by the new CA
• It should not be expired

How did we tackle te problem?

We wrote scripts to consume those excel lists, transform them and process every system / endpoint.

I had done similar tasks in te past. But not at this scale.

My first attempt involved shell scripts and openssl: Gets the job done but required way to muc time.

Next iteration was implemented in python: much better. Faster, easier to maintain - but still room for improvement.

The solution

Then i decided to to try a Rust based approach.

Clean as python and fast as hell 🔥!

Rust SSL-Cert-Checker