[TRACE] OTLP HTTP exporter console logs issues

[marcalff]

Using the OTLP HTTP exporter, and printing debug logs generated by otlp_http_client.cc leads to the following data:

2022-10-20T22:00:14.654921Z 0 [...] [OTEL DEBUG] /.../opentelemetry-cpp/opentelemetry-cpp-1.6.1/exporters/otlp/src/otlp_http_client.cc:126 [OTLP HTTP Client] Export success, Status:200Header:        Content-Length : 0^M,   Content-Type : application/x-protobuf^M,        Date : Thu, 20 Oct 2022 22:00:14 GMT^M,Body:

Note how "Status:200Header:" is printed, without spaces or comma to separate status from header.

Note how fields are printed sometime as "field:value", sometime as "field : value"
Because of this, logs are harder to parse that necessary.

If using spaces before and after ":", and a "," plus space to separate fields, then please use this consistently.

For example, print "Status : 200, Header :" instead.

The code printing this log is exporter::otlp::ResponseHandler::BuildResponseLogMessage

  std::string BuildResponseLogMessage(http_client::Response &response,
                                      const std::string &body) noexcept
  {
    std::stringstream ss;
    ss << "Status:" << response.GetStatusCode() << "Header:";
    response.ForEachHeader([&ss](opentelemetry::nostd::string_view header_name,
                                 opentelemetry::nostd::string_view header_value) {
      ss << "\t" << header_name.data() << " : " << header_value.data() << ",";
      return true;
    });
    ss << "Body:" << body;

    return ss.str();
  }

Also, as seen when reading the code in exporter::otlp::ResponseHandler::OnResponse,

      if (response.GetStatusCode() != 200 && response.GetStatusCode() != 202)
      {
        log_message = BuildResponseLogMessage(response, body_);

        OTEL_INTERNAL_LOG_ERROR("OTLP HTTP Client] Export failed, " << log_message);
        result = sdk::common::ExportResult::kFailure;
      }

      if (console_debug_)
      {
        if (log_message.empty())
        {
          log_message = BuildResponseLogMessage(response, body_);
        }
        OTEL_INTERNAL_LOG_DEBUG("[OTLP HTTP Client] Export success, " << log_message);
      }
    }

The OTEL_INTERNAL_LOG_DEBUG() log statement prints "Export success", including on failures.