How to sync clocks across machines

Or: How to sync server and client clocks.

Problem:

I'd like to measure performance marks on the server (timestamp), and then compare it to perf marks on the client, but the clock drift between those two computers is inevitable.

So... How do you solve this? You have to either sync the clocks, or get the offset between the two to normalize the time.

Curl with network timing data

curl -v -L --output /dev/null --silent --show-error --write-out "lookup:        %{time_namelookup}\nconnect:       %{time_connect}\nappconnect:    %{time_appconnect}\npretransfer:   %{time_pretransfer}\nredirect:      %{time_redirect}\nstarttransfer: %{time_starttransfer}\ntotal:         %{time_total}\n" https://google.com

^ This will show headers, and timing data for the network request. And drop body response into black hole /dev/null.

https://netbeez.net/blog/http-transaction-timing-breakdown-with-curl/

Approaches to try

https://blog.risingstack.com/measuring-http-timings-node-js/

Options

https://expressjs.com/en/resources/middleware/response-time.html ?

Reading

https://www.liquid.fish/current/syncing-the-browser-time https://www.deconstructconf.com/2019/allison-kaptur-clock-skew-and-you (conf talk) https://infiniteundo.com/post/25326999628/falsehoods-programmers-believe-about-time

https://jvns.ca/blog/2016/02/09/til-clock-skew-exists/

Current next.js discussion https://github.com/vercel/next.js/discussions/62353

Open source

Just use this? https://github.com/NodeGuy/server-date

With next.js https://github.com/vercel/next.js/issues/12382

https://gist.github.com/ethaizone/6abb1d437dbe406fbed6

TIL > architecture-lang-agnostic >