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Computing Facility

Jenkins on Theta

Jenkins at ALCF

The ALCF provides a tool for implementing CI processes named Jenkins. Using the Jenkins tool, ALCF projects can make use of CI functionality. The Jenkins CI tool enables projects to auto-compile their custom software code, automate testing cycles, provide a feedback loop, and submit jobs to HPC resources. The custom pipelines needed for each project can be defined in Jenkins by project users, and execution can be controlled through triggers.

Additional information, technical and user documentation, and community support can be found on the Jenkin's project website.

Projects Using Jenkins

Enabling a project to use Jenkins requires some additional steps and configuration to get started. Once enabled for a project, users can access the Jenkins CI environment and configure jobs or pipelines for building and testing their project code.

On-Boarding with Jenkins

To enable Jenkins for your project, send an email to support@alcf.anl.gov requesting Jenkins access for your project and include the ALCF project shortname and the PI’s name with the request.

The project’s PI will get an email with details and a new Jenkins account associated with the project. This is a service account that the Jenkins CI tool will use when executing tasks associated with your project. The CI account will be listed as a project member and added to the project’s group for access controls.

ALCF Jenkins

Log in to the ALCF Jenkins web portal using your ALCF credentials (ALCF username and cryptocard token password).

Folders

Each Jenkins project will have a top-level "folder" created with the project’s name. Please do not delete the project folder: it is used for organization in the multi-project environment and is required for implementing the needed level of security. The project folder is where all of the project objects are stored, you can additionally create any subfolders, jobs, pipelines, etc. within your project folder to meet your CI needs.

In the example below, we have a project named "TestFromJanet2" with an associated folder.

CI folders screenshot

CI folders screenshot

Nodes

Each Jenkins project will have an assigned node for execution. Nodes execute jobs defined within a project, typically on the target system’s login node. Currently there are Jenkins nodes configured for HPC systems Theta and Cooley, as well as non-HPC nodes with 32 cores (Intel Xeon Processor E5-2683 v4) and 128 GB RAM for generic x86 processing with access to the Mira shared filesystems.

In the example below, the node for this project is named ‘TestFromJanet2-Theta. Jobs and pipeline steps triggered from Jenkins will execute on the TestFromJanet2-Theta node which has been configured to use host: thetalogin1 and will use the project’s Jenkin's user ID (provided during on-boarding) to execute scripts or code just as if the end user had logged into the thetalogin1 node and executed the same set of actions manually from the command line.

CI slaves screenshot

CI slaves screenshot

Job Configuration

When configuring any new job within a project there are some guidelines to follow for setting permissions and nodes. Project data is kept secure by setting up permissions at the project level and node selection controls where the job will execute.

When creating jobs, enable project-based security, set the inheritance strategy, and add your project’s group name to the permission matrix table. The example below has enabled project-based security, set the inheritance strategy to Do not inherit permission grants from other ACLs, and added the project’s group name "TestFromJanet2" to the permission matrix granting all rights to the group.

CI permissions screenshot

CI permissions screenshot

To assign the node that the project will use to execute jobs, select the option Restrict where this project can be run and enter the project’s assigned node. The example below has assigned the jobs to node: TestFromJanet2-Theta so that any time the job is executed, it runs on host: thetalogin1.

Execute screenshot

Execute screenshot

Common Jenkins Features

Version Control Features

Jenkins can connect to most common version control systems (VCS), including git/svn. The ALCF Jenkins instance can connect with local VCS hosted at at ANL as well as with external VCS, such as that hosted at Github.

On the job configuration page, look for the section Source Code Management (SCM). If it is there already, add it to the job. The required fields for SCM are Repository URL and Credentials. The example below shows a connection to the ALCF internal Gitlab VCS and uses previously setup credentials.

Repository access

Repository access

To use the new connection to the Git repository interactively, configure the job to be parameterized and add a Git Parameter to the job. The example below shows the configuration to select a branch at build time.

Git parameter

Git parameter

On the build screen, select from the drop-down menu the branch to be referenced during this job execution. The example below shows the list of available branches from the configured repository. It is automatically populated during the Git connector configuration of the preceding steps. If a new branch is added to the Git repository, it will display in the populated list of available branches when the job runs in Jenkins.

Select branch

Select branch

Build Steps

Build steps are where users define executable tasks and jobs do something interesting within an environment. A core component of Jenkins, build steps can take a few different forms and are most commonly configured to call remote scripts for code building and deployment. A build step can even contain the shell script contents to execute on the remote machine.

Add build step

Add build step

The example below uses the Execute Shell build step type and codes the shell logic within the Jenkins portal.

Execute shell

Execute shell

Pipelines

Pipelines in Jenkins allow for more advanced execution logic and are written in Groovy. A pipeline can be added directly to your project as an object using the New Item link. More commonly, they are defined in a "Jenkinsfile" and stored in VCS along with the project code. The Jenkinsfile can be created and edited outside of the Jenkins system using any text editor.

To add a pipeline manually, select Pipeline from the new New Item dialog box.

New Item dialog box

New Item dialog box

The pipeline can then be configured and edited from the project folder in the same way as jobs, as shown in the example below.

Pipeline configuration

Pipeline configuration

To add a pipeline using a Jenkinsfile in SCM, add the pipeline object as shown below. On the pipeline configuration page, select Pipeline script from SCM and provide the SCM connection details along with the Script Path. The Script Path is the path-to and filename where the Jenkinsfile is located within the SCM repository. The example below uses a Jenkinsfile stored in the project source code from the ALCF Git repository, and the Jenkinsfile containing the Groovy code pipeline definition is located at scripts/Jenkinsfile from the repository root.

Pipeline script path

Pipeline script path

Triggers

Triggers are events that initiate tasks in Jenkins. Triggers can be called a few different ways, including directly by a user via the Build Now action (a time-based trigger similar to a Cron system), or based on commits made to source control.

The example below shows a time-based configuration to run the job on a regular schedule. Details on the scheduling syntax can be found by clicking the blue question mark to the right of the Schedule field.

Build triggers

Build triggers

Console Output

Jenkins provides console output and saves this history for each job run. During job execution you can view the live output from the tasks in a display similar to what would be seen if the commands were run directly in an interactive console.

Console output

Console output

Credentials

Credentials are stored in Jenkins and used when connecting to remote resources that require authentication in a non-interactive manner. Once defined, credentials can be used throughout the Jenkins system when configuring jobs, SCM connections, SSH connections, etc.

To add a set of credentials, click on Credentials from the available options on the left-hand navigation menu. Then select System and click on the link for Global credentials.

Credentials

Credentials

Click Add Credentials from the left-hand navigation menu and provide the required information. The example below configures a new credential set of type "SSH Username with private key." Make sure Scope is set to "Global." Provide the username, private key (copy and paste), and key passphrase, and then give a pertinent ID and detailed description to help identify and organize stored credentials in the system.

Add credentials

Add credentials

FAQS

Why does my project's execution node say it is offline? Node services for executing project tasks are initiated when there is demand for the node. The process of starting the node services can take up to one minute; the status change is displayed in the Jenkins web portal. When there is no longer demand for the node, the services will stop again after one minute of idle time.

Why is my shell environment different when executing tasks on a Jenkins node? Since Jenkins uses SSH with no tty, any shell scripts need to have this at the top so that login scripts are run against the session:

#!/bin/bash -1

Glossary

Continuous Integration (CI) - The process of automating the build and testing of code every time developers commit changes to version control.

Pipeline - A CI pipeline is a list of tasks or jobs that are defined and executed as a procedure within a project. Pipeline is analogous to workflow.

Source Control Management (SCM) - A term used in Jenkins to describe objects related to version control.

Version Control System (VCS) - Software that manages access, storage, and revision history for a code repository.

Appendix

Abbreviated Setup

  • Request Jenkins access for your project by emailing the ALCF Service Desk.
  • Add jobs and pipelines to the project folder space to handle code compiling and testing.
  • Configure jobs with credentials, SCM integrations, and trigger components depending on the intended behavior for your project.
  • Execute jobs and pipelines by invoking the configured triggers.