接続検証サンプル（再現）

client_sample.rb

require 'net/http'
require 'openssl'

uri = URI('https://host.docker.internal:8443/')
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true

# 自己署名許可
http.verify_mode = OpenSSL::SSL::VERIFY_NONE

# OpenSSL::SSL::SSLContextに直接オプションを設定
# if OpenSSL::SSL.const_defined?(:OP_IGNORE_UNEXPECTED_EOF)
#   OpenSSL::SSL::SSLContext::DEFAULT_PARAMS[:options] |= OpenSSL::SSL::OP_IGNORE_UNEXPECTED_EOF
# end

begin
  response = http.get('/')
  puts "Response: #{response.code} #{response.body}"
rescue => e
  puts "Exception: #{e.class} - #{e.message}"
end

server_sample.rb

require 'socket'
require 'openssl'

PORT_NUM = 8443

tcp_server = TCPServer.new('127.0.0.1', PORT_NUM)

# openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 1 -nodes -subj "/CN=localhost"
context = OpenSSL::SSL::SSLContext.new
context.cert = OpenSSL::X509::Certificate.new(File.read('cert.pem'))
context.key = OpenSSL::PKey::RSA.new(File.read('key.pem'))
ssl_server = OpenSSL::SSL::SSLServer.new(tcp_server, context)

puts "server is listening at port #{PORT_NUM}"

loop do
  ssl_socket = ssl_server.accept

  begin
    response_body = "Hello World"
    response = <<~HTTP
      HTTP/1.1 200 OK\r
      Content-Type: text/html\r
      Connection: close\r
      \r
      #{response_body}
    HTTP

    ssl_socket.write(response)
    ssl_socket.flush

    ssl_socket.io.close  # TLSの終了処理を踏まずに切断
  rescue => e
    puts "サーバーエラー: #{e.message}"
  ensure
    ssl_socket.close rescue nil
  end
end