Add Trafficdump tool

[pstibrany]

What this PR does: This PR adds trafficdump tool, which can read packets from device or from captured tcpdump output, reassemble them into TCP streams and parse HTTP requests and responses. It then prints requests and responses as json (one request/response par per line) for further processing.

It has some Mimir-specific and generic HTTP features:

• filter requests based on Tenant (in Basic or X-Scope-OrgId header)
• filter requests based on URL path
• filter requests based on status code of the response
• decode Mimir push requests
• filter requests based on matching series in push requests

Trafficdump can be used to inspect both remote-write requests and queries.

Checklist

• [na] Tests updated
• Documentation added
• [na] CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[osg-grafana]

@jdbaldry, did we want to keep this doc in the README.md file? I think so, but cannot remember.

[jdbaldry]

I think it would be nice to have this in the technical documentation as "About mimirtool"

[osg-grafana]

Split that off into a subsequent issue or PR.

[osg-grafana]

I think it would be nice to have this in the technical documentation as "About mimirtool"

Relates to #1014.

[osg-grafana]

Unblocking, and can update docs later too.

[pstibrany]

I plan to write a documentation shortly describing all our tools.

[replay]

I think it would be useful to have a flag which makes it not show all the warnings and errors, but only the information which it parsed successfully.

For example I tested it by doing this:

./trafficdump.linux  -r ./tcpdump -request.decode-remote-write -select '{pod="distributor-5684946f49-gfclc"}' > parsed 2>&1

And it did successfully parse out the metrics of the specified selector, but there was also quite a lot of warning/error noise:

replay@mauro-workstation:~/go/src/github.com/grafana/mimir/tools/trafficdump$ wc -l parsed
84856 parsed
replay@mauro-workstation:~/go/src/github.com/grafana/mimir/tools/trafficdump$ grep 'dropping response' parsed | wc -l
34827
replay@mauro-workstation:~/go/src/github.com/grafana/mimir/tools/trafficdump$ grep 'malformed HTTP' parsed | wc -l
45125

[pracucci]

Impressing tooling! I'm 👍 : it's just a tooling that doesn't interfere with Mimir. You already successfully used it, in my opinion for such tooling there's no need for a deep review, especially if you already successfully used it, so let's get in, let's keep using it and improving over time based on hands-on experience.

[osg-grafana]

I plan to write a documentation shortly describing all our tools.

See #1098.