For us, a `X-Request-ID` header is generated by any app if it doesn't receive it from upstream -- but normally nginx or the CDN will generate it. There's a few

For us, a `X-Request-ID` header is generated by any app if it doesn't receive it from upstream -- but normally nginx or the CDN will generate it. There's a few nginx modules to do it, we use https://github.com/newobj/nginx-x-rid-header https://github.com/newobj/nginx-x-rid-header Most languages/logging frameworks have some sort of per-thread context (eg. Filters in Python, MDC in log4j, etc) to be able to tag log messages with. If you're using postgresql, you can call `SET application_name='{requestID}';` and that can be output as part of logs too.