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The MettleCI Jenkins DataStage repository and shared library repository templates require the specification of Jenkins nodes, environment variables, and credentials. Some DataStage organisations have multiple development teams working on multiple DataStage development projects, each of which would typically require a dedicated Git repository associated with a dedicated Jenkins project and all its attendant Jenkins artefacts. Creating all of these artefacts manually for a large number of DataStage delivery streams could be very onerous and error prone. A better solution might be to automate this process using the the Jenkins Remote Access API which provides calls that can minimise the effort of creating multiple Jenkins projects (“Jobs”), Nodes, and Credentials when.

Guides

Table of Contents
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See Authenticating scripted clients (jenkins.io).

Prerequisites

In order to successfully make calls to the Jenkins REST API , you require…

  • a user with permissions to create pipelines, nodes and credentials,

  • an access token for that user, and

  • a session token, called a 'Jenkins Crumb'.

Generating the Jenkins Crumb

The following request returns the Crumb Request Field and the Crumb itself:

...

The response is in the format <JENKINS_CRUMB_REQUEST_FIELD>:<JENKINS_CRUMB>, for example:

Code Block
Jenkins-Crumb:f4a44af38ffc911d34c1c331bf292c9d57c81b3e81761b503bde0a97544a60d8

Creating a Jenkins Node

Jenkins provides a method for the creation of Nodes, including the environment variables required by the MettleCI pipeline and shared library.

JSON

Code Block
languagejson
{
  "name":"<NODE_NAME>",
  "nodeDescription":"<NODE_SESCRIPTION>",
  "numExecutors":"<NUM_EXECUTORS>",
  "remoteFS":"<REMOTE_ROOT_DIRECTORY>",
  "labelString":"<AGENT_LABELS>",
  "mode":"NORMAL",
  "":[
    "hudson.slaves.JNLPLauncher",
    "hudson.slaves.RetentionStrategy$Always"
  ],
  "launcher":{
    "stapler-class":"hudson.slaves.JNLPLauncher",
    "$class":"hudson.slaves.JNLPLauncher",
    "workDirSettings":{
      "disabled":false,
      "workDirPath":"",
      "internalDir":"remoting",
      "failIfWorkDirIsMissing":false
    },
    "webSocket":false,
    "tunnel":"",
    "vmargs":"",
    "oldCommand":""
  },
  "retentionStrategy":{
    "stapler-class":"hudson.slaves.RetentionStrategy$Always",
    "$class":"hudson.slaves.RetentionStrategy$Always"
  },
  "nodeProperties":{
    "stapler-class-bag":"true",
    "hudson-slaves-EnvironmentVariablesNodeProperty":{
      "env":[
        {
          "key":"AGENTMETTLECMD",
          "value":"<AGENT_METTLE_CMD>"
        },
        {
          "key":"AGENTMETTLEHOME",
          "value":"<AGENT_METTLE_HOME>"
        },
        {
          "key":"IISDOMAINNAME",
          "value":"<IIS_DOMAIN_NAME>"
        },
        {
          "key":"IISENGINENAME",
          "value":"<IIS_ENGINE_NAME>"
        },
        {
          "key":"IISUSERNAME",
          "value":"<IIS_USERNAME>"
        },
        {
          "key":"IISPASSWORD",
          "value":"<IIS_PASSWORD_CRED>"
        },
        {
          "key":"IISPROJECTTEMPLATEDIR",
          "value":"<DATASTAGE_PROJECT_TEMPLATE_DIR>"
        },
        {
          "key":"MCIUSERNAME",
          "value":"<MCI_USERNAME>"
        },
        {
          "key":"MCIPASSWORD",
          "value":"<MCI_PASSWORD_CRED>"
        },
        {
          "key":"ENGINEUNITTESTBASEDIR",
          "value":"ENGINE_UNITTEST_BASE_DIR>"
        }
      ]
    }
  },
  "type":"hudson.slaves.DumbSlave",
  "<JENKINS_CRUMB_REQUEST_FIELD>":"<JENKINS_CRUMB>"
}

...

Code Block
languagebash
$> curl -L -s \
   -o /dev/null \
   -w "%{http_code}" \
   -u <JENKINS_USER>:<ACCESS_TOKEN> \
   -H "Content-Type:application/x-www-form-urlencoded" \
   -H '<JENKINS_CRUMB_REQUEST_FIELD>:<JENKINS_CRUMB>' \
   -X POST \
   -d "json=<JSON_TEXT>" \
   '<JENKINS_URL>:<JENKINS_PORT>/computer/doCreateItem?name=<NODE_NAME>&type=hudson.slaves.DumbSlave'

Creating a Jenkins Pipeline

The process to create a new Jenkins Pipeline requires the input in XML. Here is the XML configuration file for a default MettleCI pipeline:

XML

Code Block
languagexml
<flow-definition plugin="workflow-job@1186.v8def1a_5f3944">
	<actions>
		<org.jenkinsci.plugins.pipeline.modeldefinition.actions.DeclarativeJobAction plugin="pipeline-model-definition@2.2086.v12b_420f036e5"/>
		<org.jenkinsci.plugins.pipeline.modeldefinition.actions.DeclarativeJobPropertyTrackerAction plugin="pipeline-model-definition@2.2086.v12b_420f036e5">
			<jobProperties/>
			<triggers/>
			<parameters/>
			<options/>
		</org.jenkinsci.plugins.pipeline.modeldefinition.actions.DeclarativeJobPropertyTrackerAction>
	</actions>
	<description>PIPELINE_DESCRIPTION</description>
	<keepDependencies>false</keepDependencies>
	<properties>
		<hudson.plugins.jira.JiraProjectProperty plugin="jira@3.7.1"/>
		<org.jenkinsci.plugins.workflow.job.properties.DisableConcurrentBuildsJobProperty>
			<abortPrevious>false</abortPrevious>
		</org.jenkinsci.plugins.workflow.job.properties.DisableConcurrentBuildsJobProperty>
		<org.jenkinsci.plugins.workflow.job.properties.PipelineTriggersJobProperty>
			<triggers>
				<hudson.triggers.SCMTrigger>
					<spec>SCM_POLLING_SCHEDULE</spec>
					<ignorePostCommitHooks>false</ignorePostCommitHooks>
				</hudson.triggers.SCMTrigger>
			</triggers>
		</org.jenkinsci.plugins.workflow.job.properties.PipelineTriggersJobProperty>
	</properties>
	<definition class="org.jenkinsci.plugins.workflow.cps.CpsScmFlowDefinition" plugin="workflow-cps@2725.v7b_c717eb_12ce">
		<scm class="hudson.plugins.git.GitSCM" plugin="git@4.11.3">
			<configVersion>2</configVersion>
			<userRemoteConfigs>
				<hudson.plugins.git.UserRemoteConfig>
					<url>GIT_PROJECT_REPOSITORY_URL</url>
					<credentialsId>GIT_PROJECT_REPOSITORY_CRED</credentialsId>
				</hudson.plugins.git.UserRemoteConfig>
			</userRemoteConfigs>
			<branches>
				<hudson.plugins.git.BranchSpec>
					<name>*/master</name>
				</hudson.plugins.git.BranchSpec>
			</branches>
			<doGenerateSubmoduleConfigurations>false</doGenerateSubmoduleConfigurations>
			<submoduleCfg class="empty-list"/>
			<extensions/>
		</scm>
		<scriptPath>Jenkinsfile</scriptPath>
		<lightweight>true</lightweight>
	</definition>
	<triggers/>
	<disabled>false</disabled>
</flow-definition>

...

Code Block
$> curl -L -s \
   -o /dev/null -w "%{http_code}" \
   -H "Content-Type:text/xml" \
   -H '<JENKINS_CRUMB_REQUEST_FIELD>:<JENKINS_CRUMB>' \
   -X POST \
   -u '<JENKINS_USER>:<ACCESS_TOKEN>' \
   '<JENKINS_URL>:<JENKINS_PORT>/createItem?name=<PIPELINE_NAME>' \
   --data-binary @NewPipeline.xml

Creating Jenkins Credentials

When setting up the Jenkins Nodes used by the MettleCI pipelines, there are two environment variables for storing passwords:

...

Unlike the other environment variables which contain text, these 2 variables actually store the Id of the Jenkins Credential that contains the password. This means that if we are creating multiple Nodes relating to different Information Server instances, we need to create credentials to match.

JSON

Code Block
languagejson
{
	"": "0",
	"credentials": { 
		"scope": "GLOBAL", 
		"id": "<CREDENTIAL_ID>", 
		"secret": "<PASSWORD>", 
		"description": "<CREDENTIAL_DESCRIPTION>", 
		"$class": "org.jenkinsci.plugins.plaincredentials.impl.StringCredentialsImpl" 
	} 
}

...