For one interview, the take home challenge was to write a bit.ly clone. I decided I would show off my abilities to do load balancing on the web server and horizontally scale a database.

I wrote my application with a dockerfile for ease of deployment. I set up multiple A records to point to each docker container's IP for a simple DNS round robin load balancing. Each container had a unique hash string printed in the bottom right corner of the website so you could demonstrate to yourself that load balancing was occurring.

I set up 3 postgres databases with simple modulo hashing for each shard; I use an 8 character hashing function (forget which) and did a modulo on the number of shards. This directed each shortened link to its relevant shard, with the shortened form of the link as the key (note: this is not the best solution to the problem; look up consistent hashing if you want a better solution). Which database connection string to use depended on the result of this modulo

All this was deployed with relevant kubernetes service and deployment yaml files, with ci/cd hooks provided by my VPS (I think vultr or digitalocean)

When I was explaining all this in the interview, I was actually interviewing with someone who was lower ranked than the job I was interviewing for (she was a junior engineer with maybe 2 or 3 years of experience, I was interviewing for a mid level role with 5 years of experience)

She said "so, it seems like you're more interested in devops than application development?"

I said "no, I actually really hate devops, but these are the skills I get interviewed on most so its what I practice".

I didnt end up taking that job.