Having the ability to call Jenkins jobs remotely is pretty slick and adds some extra flexibility and allows for some interesting applications. For example, you could use remote builds to call a script from a chat app or from some other web application. I have chosen to write a quick bash script as a proof of concept, but this could easily be extended or written in a different language via one of its language specific libraries.
The instructions for the method I am using assume that you are using the Jenkins freestyle build as I haven’t experimented much yet with pipelines for remote builds yet.
The first step is to enable remote builds for the Jenkins job that will be triggered. There is an option in the job for “Trigger builds remotely” which allows the job to be called from a script.
The authentication token can be any arbitrary string you choose. Also note the URL below, you will need that later as part of the script to call this job.
With the authentication token configured and the Jenkins URL recorded, you can begin writing the script. The first step is to populate some variables for kicking off the job. Below is an example of how you might do this.
jenkins_url="https://jenkins.example.com" job_name="my-jenkins-job" job_token="xxxxx" auth="username:token" my_repo="some_git_repo" git_tag="abcd123"
Be sure to fill in these variables with the correctly corresponding values. job_token should correspond to the string you entered above in the Jenkins job, auth should correspond to your github username/token combination. If you are not familiar with Github tokens you can find more information about setting them up here.
As part of the script, you will want to create a Jenkins “crumb” using your Github credentials that will be used to prevent cross-site scripting attacks. Here’s what the creation of the crumb looks like (borrowed from this Stackoverflow post).
crumb=$(curl -s 'https://'auth'@jenkins.example.com/crumbIssuer/api/xml?xpath=concat(//crumbRequestField,":",//crumb)')
Once you have your variables configured and your crumb all set up, you can test out the Jenkins job.
curl -X POST -H "$crumb" $jenkins_url/job/$job_name/build?token=$job_token \
--user $auth \
--data-urlencode json='
{"parameter":
[
{"name":"parameter1", "value":"test1"},
{"name":"parameter2", "value":"test2"},
{"name":"git_repo", "value":"'$my_repo'"},
{"name":"git_tag", "value":"'$git_tag'"}
]
}'
In the example job above, I am using several Jenkins parameters as part of the build. The json name values correspond to the parameters. Notice that I am using variables for a few of the values above, make sure those variables are wrapped in singe quotes to correctly escape the json. The syntax for variables is slightly different but allows for some additional flexibility in the job configuration and also allows the script to be called with dynamic values.
If you call this script now, it should kick off a Jenkins job for you with all of the values you have provided.
