Module: Kernel

Defined in:
lib/online.rb

Overview

Checks whether we are online now.

Author

Yegor Bugayenko ([email protected])

Copyright

Copyright © 2024-2025 Yegor Bugayenko

License

MIT

Defined Under Namespace

Modules: OnlineOrOffline

Instance Method Summary collapse

Instance Method Details

#online?(uri: 'https://www.google.com/generate_204', ttl: 300, timeout: 10) ⇒ Boolean

Note:

The method has a 10-second timeout to prevent hanging on slow connections

Note:

Returns false for any network-related errors including timeouts, DNS failures, and unreachable hosts

Note:

Results are cached with a default TTL of 5 minutes to reduce network requests

Checks whether the system has an active internet connection by attempting to connect to a specified URI.

This method performs an HTTP GET request to verify connectivity. It’s useful for checking internet availability before performing network-dependent operations or for implementing offline-mode functionality in applications.

Examples:

Basic usage - check internet connectivity

if online?
  puts "Connected to the internet!"
else
  puts "No internet connection available"
end

Check connectivity to a specific service

if online?('https://api.github.com')
  # Proceed with GitHub API calls
else
  # Use cached data or show offline message
end

Check with custom cache TTL (10 minutes)

if online?(ttl: 600)
  # Will use cached result for 10 minutes
end

Use in Minitest tests

require 'minitest/autorun'
require 'online'

class MyServiceTest < Minitest::Test
  def test_api_call_when_online
    skip("No internet connection") unless online?
    # Test code that requires internet
  end

  def test_offline_fallback
    unless online?
      assert_equal cached_data, service.fetch_data
    end
  end
end

Conditional feature loading

class WeatherWidget
  def display
    if online?('https://api.weather.com')
      show_live_weather
    else
      show_cached_weather
    end
  end
end

Parameters:

  • uri (String) (defaults to: 'https://www.google.com/generate_204') —

    the URI to check connectivity against (default: ‘www.google.com/generate_204’)

  • ttl (Integer) (defaults to: 300) —

    time-to-live for cached results in seconds (default: 300 seconds = 5 minutes)

  • timeout (Integer) (defaults to: 10) —

    open, read and write HTTP timeout (default: 10 seconds)

Returns:

  • (Boolean) —

    true if the URI is reachable and returns HTTP success, false otherwise



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# File 'lib/online.rb', line 89

def online?(uri: 'https://www.google.com/generate_204', ttl: 300, timeout: 10)
  raise 'The URI is nil' if uri.nil?
  raise 'The TTL is nil' if ttl.nil?
  key = uri.to_s
  OnlineOrOffline.mutex.synchronize do
    entry = OnlineOrOffline.cache[key]
    return entry[:status] if entry && (Time.now - entry[:time]) < ttl
    uri = URI(uri) unless uri.is_a?(URI)
    status =
      begin
        Net::HTTP.start(
          uri.hostname,
          uri.port,
          use_ssl: uri.scheme == 'https',
          open_timeout: timeout,
          read_timeout: timeout,
          write_timeout: timeout
        ) do |http|
          http.request_get(uri, {}).is_a?(Net::HTTPSuccess)
        end
      rescue \
        Socket::ResolutionError, Net::OpenTimeout, Net::ReadTimeout, Net::WriteTimeout,
        Errno::EHOSTUNREACH, Errno::EINVAL, Errno::EADDRNOTAVAIL, Errno::EBADF
        false
      end
    OnlineOrOffline.cache[key] = { status: status, time: Time.now }
    status
  end
end