A section of config/puma.rb that will automatically generate a self-signed X509 certificate and provide https in development

puma.rb

if Rails.env.development?
  FileUtils.mkdir_p(Rails.root.join('config', 'certs'))
  key_path = Rails.root.join('config', 'certs', 'development.key')
  crt_path = Rails.root.join('config', 'certs', 'development.crt')
  unless File.exist?(key_path) && File.exist?(crt_path)

    def cert_domain
      'localhost' # Setting[:cookie_domain] || 'localhost'
    end

    def generate_cert(key, subject)
      cert = OpenSSL::X509::Certificate.new
      cert.version = 2
      cert.serial = 0x0
      cert.subject = cert.issuer = subject
      cert.public_key = key.public_key
      cert.not_before = Time.now
      cert.not_after = Time.now + 2.years
      extend_and_sign(cert, key)
    end

    def extend_and_sign(cert, key)
      ef = OpenSSL::X509::ExtensionFactory.new
      ef.subject_certificate = ef.issuer_certificate = cert
      cert.add_extension(ef.create_extension('keyUsage', 'digitalSignature', true))
      cert.add_extension(ef.create_extension('extendedKeyUsage', 'serverAuth', true))
      cert.add_extension(ef.create_extension('subjectAltName', "DNS.1:#{cert_domain},DNS.2:*.#{cert_domain}", true))
      cert.sign(key, OpenSSL::Digest.new('SHA256'))
    end

    begin
      subject = OpenSSL::X509::Name.parse("/L=Los Angeles/C=US/O=AINZ/OU=TOP/ST=CA/CN=#{cert_domain}")
      key = OpenSSL::PKey::RSA.new(2048)
      FileUtils.rm key_path, force: true
      file = File.new(key_path, 'wb')
      file.write(key)
      file.close

      cert = generate_cert(key, subject)
      FileUtils.rm crt_path, force: true
      file = File.new(crt_path, 'wb')
      file.write(cert)
      file.close
    rescue StandardError => e
      Rails.logger.warn "An error occurred creating the SSL certificate in development: #{e.message}.. Skipping SSL!"
      FileUtils.rm key_path, force: true
      FileUtils.rm crt_path, force: true
    end
  end

  if File.exist?(key_path) && File.exist?(crt_path)
    ssl_bind '0.0.0.0', '3001', {
      key: key_path,
      cert: crt_path
    }
  end
end