Small ruby script that sends a text message to a Slack channel

send_message_slack.rb

require 'uri'
require 'json'
require 'net/http'

# Create a slack app https://api.slack.com/start
# More information in https://api.slack.com/messaging/sending

ACCESS_TOKEN = '<access token of your app>'
SLACK_URL_POST = 'https://slack.com/api/chat.postMessage'

def send_message(channel_id, text)
  headers = { 'Content-Type': 'application/json', 'Authorization': "Bearer #{ACCESS_TOKEN}" }
  
  request = Net::HTTP::Post.new(uri.request_uri, headers)
  request.body = { channel: channel_id, text: text }.to_json
  
  uri = URI(SLACK_URL_POST)

  https = Net::HTTP.new(uri.host, uri.port)
  https.use_ssl = true
  https.request(request)
end

# Put the channel id where desire send a message 
# https://www.wikihow.com/Find-a-Channel-ID-on-Slack-on-PC-or-Mac
response = send_message('<channel id>', 'Hello channel!')

puts 'Response:'
p JSON.parse(response.body)