Tip of the day: validating a Jenkinsfile from the CLI with HTTPie

An easily missed feature in Jenkins is the bundled linter for Jenkinsfiles.

While there are many examples about how to use it with cURL, I could not find any using HTTPie, which I find much more convenient in general than cURL. So, after some fumbling due to the little documented expectations of the validator, here is the solution showing how to validate a Jenkinsfile from the CLI:

http --form                                         \
     -a $USER:$PASS                                 \
     -pb                                            \
     POST                                           \
     $JENKINS_URL/pipeline-model-converter/validate \
     jenkinsfile=@$JENKINSFILE

Let's see what these arguments mean:

• --form specifies use of the application/x-www-form-urlencoded MIME type, as expected by the validator
• -a $USER:$PASS provides basic authentication credentials.
  • If you do not want to include the password, just use $USER: and HTTPie will request the password on the CLI.
  • This assumes these two variables contain your Jenkins username and password
• -pb asks HTTPie to only print the response body
• $JENKINS_URL is the absolute URL to the Jenkins root
• $JENKINSFILE is the path to the Jenkinsfile to validate. May be relative or absolute

That's it. Note that, as usual with HTTPie, the ordering is strict:

1. http the command itself
2. The options, like -a and --form
3. The method, in this case POST. HTTPie uses GET by default
4. The target URL
5. The so-called "fields", which translate to the request body. In this case, the jenkinsfile=@$JENKINSFILE requests HTTPie to load the contents of the file designated by $JENKINSFILE and load that content as the value of the jenkinsfile HTML form field

Hopefully, you will receive a result looking like this:

Jenkinsfile successfully validated.

More details in the HTTPie forms documentation.