Demo Jenkins REST API install a plugin

Leverage the Jenkins REST API to automate common CI/CD tasks—listing jobs, inspecting job details, triggering parameterized builds, and installing plugins programmatically. This tutorial demonstrates each step using curl commands, JSON/XML endpoints, and Jenkins API tokens.

Key Jenkins REST API Endpoints

1. Retrieving the List of Jobs

Fetch all jobs in JSON and limit the fields with the tree parameter to minimize payload:

curl http://JENKINS_URL/api/json?tree=jobs[name]

Sample response:

{
  "_class": "hudson.model.Hudson",
  "jobs": [
    {"_class":"hudson.model.FreeStyleProject","name":"ascii-build-job"},
    {"_class":"hudson.model.FreeStyleProject","name":"ascii-deploy-job"},
    {"_class":"hudson.model.FreeStyleProject","name":"ascii-test-job"},
    {"_class":"hudson.model.FreeStyleProject","name":"Generate ASCII Artwork"},
    {"_class":"org.jenkinsci.plugins.workflow.job.WorkflowJob","name":"hello-world-pipeline"},
    {"_class":"org.jenkinsci.plugins.workflow.multibranch.WorkflowMultiBranchProject","name":"jenkins-hello-world"},
    {"_class":"org.jenkinsci.plugins.workflow.job.WorkflowJob","name":"parameterized-pipeline-job"}
  ]
}

The tree=jobs[name] query reduces the JSON to just the name field of each job.

2. Retrieving Job Details

Query a specific job’s API endpoint with authentication. Using jq formats the JSON:

curl -u admin:API_TOKEN \
  http://JENKINS_URL/job/parameterized-pipeline-job/api/json | jq

Abbreviated example output:

{
  "name": "parameterized-pipeline-job",
  "url": "http://JENKINS_URL/job/parameterized-pipeline-job/",
  "buildable": true,
  "builds": [
    {"number":5,"url":".../job/parameterized-pipeline-job/5/"},
    {"number":4,"url":".../job/parameterized-pipeline-job/4/"}
  ],
  "nextBuildNumber": 6,
  "property": [
    {
      "_class": "hudson.model.ParametersDefinitionProperty",
      "parameterDefinitions": [
        {
          "name": "BRANCH_NAME",
          "defaultParameterValue": {"value": "main"},
          "description": "The Git branch to build"
        },
        {
          "name": "APP_PORT",
          "defaultParameterValue": {"value": "6767"},
          "description": "Application port for tests"
        }
      ]
    }
  ]
}

3. Triggering a Build with Parameters

Use the buildWithParameters endpoint to start a parameterized job. Always use the POST method:

curl -u admin:API_TOKEN \
  -X POST \
  http://JENKINS_URL/job/parameterized-pipeline-job/buildWithParameters \
  -d BRANCH_NAME=test \
  -d APP_PORT=6767

3.1 Obtaining and Using a Crumb

1. Fetch the crumb from Jenkins:

   CRUMB=$(curl -u admin:API_TOKEN \
     http://JENKINS_URL/crumbIssuer/api/json | jq -r .crumb)
   

2. Include the crumb in your build request:

   curl -u admin:API_TOKEN \
     -H "Jenkins-Crumb:$CRUMB" \
     -X POST \
     http://JENKINS_URL/job/parameterized-pipeline-job/buildWithParameters \
     -d BRANCH_NAME=test \
     -d APP_PORT=6767
   

After triggering, verify in the Jenkins UI that build #6 is “in progress”:

4. Installing a Plugin via REST API

You can install plugins by posting an XML payload to the installNecessaryPlugins endpoint.

curl -u admin:API_TOKEN \
  -X POST http://JENKINS_URL/pluginManager/installNecessaryPlugins \
  -H 'Content-Type: text/xml' \
  -d '<jenkins>
        <install plugin="[email protected]" />
        <!-- Add more <install plugin="groupId/artifactId@version" /> entries as needed -->
      </jenkins>'

Once the request completes, navigate to Manage Jenkins → Manage Plugins → Advanced to monitor download progress:

Conclusion

In this article, you have learned how to:

• List and filter jobs using the Jenkins REST API
• Retrieve detailed metadata for a given job
• Trigger parameterized builds, handling CSRF crumbs
• Install and manage Jenkins plugins programmatically

Use these API techniques to integrate Jenkins into your automation workflows and scale your CI/CD pipelines.

Links and References

• Jenkins REST API Reference
• Jenkins Pipeline Syntax
• Jenkins CSRF Protection