title: How to configure jenkins slack plugin?
body: <p>I tried to configure jenkins slack plugin to send a notification to slack channel. But it doesn't work. I followed below instruction:</p>
  
  <pre><code>1. Get a Slack account: https://slack.com/
  2. Configure the Jenkins integration: https://my.slack.com/services/new/jenkins-ci
  3. Install this plugin on your Jenkins server.
  4. Configure it in your Jenkins job (and optionally as global configuration) and add it as a Post-build action.
  </code></pre>
  
  <p>After I install <code>jenkins</code> on slack app there is a instruction about how to configure jenkins. But the configuration fields mentioned on the instruction is a little different than my jenkins configuration.</p>
  
  <p>Below is the configuration screenshot from the instruction:</p>
  
  <p><a href="https://i.stack.imgur.com/qvm1v.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qvm1v.png" alt="enter image description here"></a></p>
  
  <p>the configuration for my jenkins server looks like below:</p>
  
  <p><a href="https://i.stack.imgur.com/xJYc6.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xJYc6.png" alt="enter image description here"></a></p>
  
  <p>how can I fill in the <code>Base URL</code> in my configuration? I have tried to fill in my <code>jenkins url</code> but it doesn't work. The test connection failed. </p>
  
  <p>I get below error in jenkins system log:</p>
  
  <pre><code>Slack post may have failed. Response: &lt;html&gt;&lt;head&gt;&lt;meta http-equiv='refresh' content='1;url=/login?from=%2FOPRc9G4zB2JX289VOnTvfeey'/&gt;&lt;script&gt;window.location.replace('/login?from=%2FOPRc9G4zB2JX289VOnTvfeey');&lt;/script&gt;&lt;/head&gt;&lt;body style='background-color:white; color:white;'&gt;
  
  
  Authentication required
  &lt;!--
  You are authenticated as: anonymous
  Groups that you are in:
  
  Permission you need to have (but didn't): hudson.model.Hudson.Read
   ... which is implied by: hudson.security.Permission.GenericRead
   ... which is implied by: hudson.model.Hudson.Administer
  --&gt;
  </code></pre>
  
  <p>I have tried to leave base url empty but still doesn't work</p>