Rails controller code to dump raw HTTP headers from a request

http_headers_dump.rb

logger.warn "*** BEGIN RAW REQUEST HEADERS ***"
self.request.env.each do |header|
  logger.warn "HEADER KEY: #{header[0]}"
  logger.warn "HEADER VAL: #{header[1]}"
end
logger.warn "*** END RAW REQUEST HEADERS ***"

self.request.env.select {|k,v| k =~ /^HTTP_/}

Log all request header keys (even if they don't start with "HTTP_", but no internal rails env stuff, in rails 5.1.4:

request.env.to_hash.select{ |key,val| ! key.starts_with?("rack") && ! key.starts_with?("action_")}

Integrating with a remote server with poorly documented auth, I needed to be able to see what the auth header was, and couldn't assume anything about the name. But I wanted to avoid logging anything about the internal state of the Rails instance to plain-text logs - in case there's anything secure in the rails env. This gets request headers (regardless of their naming convention) but no internal stuff, in rails 5.1.4.

@neilsy The HTTP_ prefix gets added for all request headers by rails / rack AFAIK, it does not come from the actual client request.