text: import re
  import subprocess
  
  import backoff
  import docker
  import pytest
  
  docker_client = docker.from_env()
  
  
  ###############################################################################
  #
  # Tests helpers
  #
  ###############################################################################
  
  @backoff.on_exception(backoff.constant, AssertionError, interval=2, max_tries=15, jitter=None)
  def assert_log_contains(expected_log_line):
      """
      Check that the nginx-proxy container log contains a given string.
      The backoff decorator will retry the check 15 times with a 2 seconds delay.
  
      :param expected_log_line: string to search for
      :return: None
      :raises: AssertError if the expected string is not found in the log
      """
      sut_container = docker_client.containers.get("nginxproxy")
      docker_logs = sut_container.logs(stdout=True, stderr=True, stream=False, follow=False)
      assert expected_log_line in docker_logs
  
  
  def require_openssl(required_version):
      """
      This function checks that the required version of OpenSSL is present, and skips the test if not.
      Use it as a test function decorator:
  
          @require_openssl("2.3.4")
          def test_something():
              ...
  
      :param required_version: minimal required version as a string: "1.2.3"
      """
  
      def versiontuple(v):
          clean_v = re.sub("[^\d\.]", "", v)
          return tuple(map(int, (clean_v.split("."))))
  
      try:
          command_output = subprocess.check_output(["openssl", "version"])
      except OSError:
          return pytest.mark.skip("openssl command is not available in test environment")
      else:
          if not command_output:
              raise Exception("Could not get openssl version")
          openssl_version = command_output.split()[1]
          return pytest.mark.skipif(
              versiontuple(openssl_version) < versiontuple(required_version),
              reason="openssl v%s is less than required version %s" % (openssl_version, required_version))
  
  
  ###############################################################################
  #
  # Tests
  #
  ###############################################################################
  
  def test_dhparam_is_not_generated_if_present(docker_compose):
      sut_container = docker_client.containers.get("nginxproxy")
      assert sut_container.status == "running"
  
      assert_log_contains("Custom dhparam.pem file found, generation skipped")
  
      # Make sure the dhparam in use is not the default, pre-generated one
      default_checksum = sut_container.exec_run("md5sum /app/dhparam.pem.default").split()
      current_checksum = sut_container.exec_run("md5sum /etc/nginx/dhparam/dhparam.pem").split()
      assert default_checksum[0] != current_checksum[0]
  
  
  def test_web5_https_works(docker_compose, nginxproxy):
      r = nginxproxy.get("https://web5.nginx-proxy.tld/port", allow_redirects=False)
      assert r.status_code == 200
      assert "answer from port 85\n" in r.text
  
  
  @require_openssl("1.0.2")
  def test_web5_dhparam_is_used(docker_compose):
      sut_container = docker_client.containers.get("nginxproxy")
      assert sut_container.status == "running"
  
      host = "%s:443" % sut_container.attrs["NetworkSettings"]["IPAddress"]
      r = subprocess.check_output(
          "echo '' | openssl s_client -connect %s -cipher 'EDH' | grep 'Server Temp Key'" % host, shell=True)
      assert "Server Temp Key: X25519, 253 bits\n" == r
  