`handle_connection handler error` is noisy and logs at `Logging.Error` level

[krynju]

This is the common case where a connection is established but then client drops
Very noisy in logs and there's no way to filter this reasonably without using LogginExtras.withlevel (which isn't documented I think)

We may want to change it to Debug

below is the simplest example where i start a server, curl and ctrl c and get the error after the ~10s sleep

julia> # HTTP.listen! and HTTP.serve! are the non-blocking versions of HTTP.listen/HTTP.serve
       server = HTTP.serve!() do request::HTTP.Request
          @show request
          @show request.method
          @show HTTP.header(request, "Content-Type")
          @show request.body
          sleep(10)
          try
              return HTTP.Response("Hello")
          catch e
              return HTTP.Response(400, "Error: $e")
          end
       end
[ Info: Listening on: 127.0.0.1:8081, thread id: 1
HTTP.Servers.Server{HTTP.Servers.Listener{Nothing, Sockets.TCPServer}}(HTTP.Servers.Listener{Nothing, Sockets.TCPServer}(Sockets.InetAddr{Sockets.IPv4}(ip"127.0.0.1", 8081), "127.0.0.1", "8081", nothing, Sockets.TCPServer(RawFD(21) active)), nothing, Set{HTTP.Connections.Connection}(), Task (runnable) @0x00007f7b9c528010)

julia> # now I curl localhost:8081 and ctrl+c 

julia> request = HTTP.Messages.Request:
"""
GET / HTTP/1.1
Host: localhost:8081
User-Agent: curl/8.4.0
Accept: */*

"""
request.method = "GET"
HTTP.header(request, "Content-Type") = ""
request.body = UInt8[]
┌ Error: handle_connection handler error. 
│ 
│ ===========================
│ HTTP Error message:
│ 
│ ERROR: IOError: write: broken pipe (EPIPE)
│ Stacktrace:
│   [1] uv_write(s::Sockets.TCPSocket, p::Ptr{UInt8}, n::UInt64)
│     @ Base ./stream.jl:1066
│   [2] unsafe_write(s::Sockets.TCPSocket, p::Ptr{UInt8}, n::UInt64)
│     @ Base ./stream.jl:1120
│   [3] unsafe_write
│     @ ~/.julia/packages/HTTP/SN7VW/src/Connections.jl:129 [inlined]
│   [4] write
│     @ ./strings/io.jl:244 [inlined]
│   [5] write
│     @ ./io.jl:676 [inlined]
│   [6] unsafe_write(http::HTTP.Streams.Stream{HTTP.Messages.Request, HTTP.Connections.Connection{Sockets.TCPSocket}}, p::Ptr{UInt8}, n::UInt64)
│     @ HTTP.Streams ~/.julia/packages/HTTP/SN7VW/src/Streams.jl:95
│   [7] write
│     @ ./strings/io.jl:244 [inlined]
│   [8] write(io::HTTP.Streams.Stream{HTTP.Messages.Request, HTTP.Connections.Connection{Sockets.TCPSocket}}, s::Base.CodeUnits{UInt8, String})
│     @ Base ./strings/basic.jl:761
│   [9] (::HTTP.Handlers.var"#1#2"{var"#9#10"})(stream::HTTP.Streams.Stream{HTTP.Messages.Request, HTTP.Connections.Connection{Sockets.TCPSocket}})
│     @ HTTP.Handlers ~/.julia/packages/HTTP/SN7VW/src/Handlers.jl:61
│  [10] #invokelatest#2
│     @ ./essentials.jl:819 [inlined]
│  [11] invokelatest
│     @ ./essentials.jl:816 [inlined]
│  [12] handle_connection(f::Function, c::HTTP.Connections.Connection{Sockets.TCPSocket}, listener::HTTP.Servers.Listener{Nothing, Sockets.TCPServer}, readtimeout::Int64, access_log::Nothing)
│     @ HTTP.Servers ~/.julia/packages/HTTP/SN7VW/src/Servers.jl:450
│  [13] macro expansion
│     @ ~/.julia/packages/HTTP/SN7VW/src/Servers.jl:386 [inlined]
│  [14] (::HTTP.Servers.var"#16#17"{HTTP.Handlers.var"#1#2"{var"#9#10"}, HTTP.Servers.Listener{Nothing, Sockets.TCPServer}, Set{HTTP.Connections.Connection}, Int64, Nothing, Base.Semaphore, HTTP.Connections.Connection{Sockets.TCPSocket}})()
│     @ HTTP.Servers ./task.jl:514
└ @ HTTP.Servers ~/.julia/packages/HTTP/SN7VW/src/Servers.jl:465

code ref

HTTP.jl/src/Servers.jl

Lines 461 to 465 in 5cd586d

	# The remote can close the stream whenever it wants to, but there's nothing
	# anyone can do about it on this side. No reason to log an error in that case.
	level = e isa Base.IOError && !isopen(c) ? Logging.Debug : Logging.Error
	msg = current_exceptions_to_string()
	@logmsgv 1 level "handle_connection handler error. $msg"

[Narik1]

Hi, just looking to bump this (sorry if this isn't the appropriate way to do it!). I am running into this issue consistently, and I would rather my logs are not populated with "expected error" messages. Not sure what the process is to get this changed?

[krynju]

You can use this to avoid these log messages.
I'll rebase that PR, there's some conflicts. There wasn't much interest in merging it though

    loglevel = Logging.current_logger().min_level
    httpserver = LoggingExtras.withlevel(loglevel; verbosity=0) do
        HTTP.listen!(...)
    end

[quinnj]

This is fixed in the 2.0 release where we have a new helper _classify_server_conn_error that will suppress these kind of noisy logging situations.