Best Practices in Using Jenkins to Run Terraform for IaC Management

Terraform is a well-known tool for Infrastructure-as-Code (IaC) management. It provides a host of functions that make it easy to manage infrastructure, especially with its declarative configuration, multi-cloud support, immutability, and idempotent operations. Terraform can also be used with complementing tools to build resilient infrastructures.

IaC management with Terraform benefits can be enhanced with the help of solutions that offer more capabilities. One of these notable solutions is Jenkins, an open-source automation server useful in building, testing, and deploying code. Jenkins is designed for continuous integration and continuous delivery (CI/CD), which makes it a perfect match for IaC configuration and management with Terraform.
Using Jenkins is not as straightforward as users hope it would be, though. There are pitfalls to avoid and methods to maximize efficiency. Here’s a rundown of the best practices to make the most out of Jenkins and Terraform.

Pay attention to role-based access control

One of the critical things to remember when using Jenkins for Terraform management is Jenkins’ lack of a robust native role-based access control (RBAC) system. Implementing RBAC in Jenkins is largely a manual process that also requires the installation of plugins such as the Role Strategy plugin. Users will have to dig deep into the software's access control functions to ascertain that only those who have explicit authority can access the different pipeline stages.

RBAC is a critical feature in securing an infrastructure and ensuring the integrity of operations. It provides a systematic way of determining which users have the authority to execute or approve changes in the pipeline. Without it, organizations will not only have problems with unauthorized or anomalous modifications. Even without malicious intentions, the lack of a systematic mechanism for authorized pipeline changes can result in chaotic operations. RBAC puts stability and order in operations to avoid configuration shifts and the emergence of system vulnerabilities.

Jenkins operates under a controlled environment, which means that it will produce the desired outcomes as long as there are no unexpected factors or interventions in how it is set to work. This is not how real-world scenarios proceed, though. Systems rarely work as intended unless there are stringent rules and guardrails put in place. Hence, role-based access control is important in using Jenkins, and it usually takes some effort and the installation of an additional plugin.

Set up automatic triggering

Efficient continuous integration and deployment is a key benefit of using Jenkins with Terraform. However, this may not be maximized without automatic triggering. Automatic triggering is not compulsory but it is preferable to have pipelines triggered automatically by specific events. For instance, whenever a commit is set for a certain branch, the pipeline should be actuated instantaneously to ensure the application of the changes carried out in the new commits.

Automatic triggering is an essential feature of a CI/CD workflow, wherein code changes need to be regularly merged into a shared repository. It enables the triggering of the Jenkins pipeline whenever there are code changes. This, in turn, executes the Terraform scripts written for infrastructure provisioning or updating.

Additionally, automatic triggering with Jenkins facilitates scheduled builds and deployments, parallel pipeline executions, and event-driven workflows. Jenkins can be set to trigger a Terraform deployment as a consequence of specific events like the generation of a new branch, completion of a pipeline stage, and the availability of new artifacts.

There are two main ways to set up automatic triggering. The first is by triggering events through a webhook. Another is by making Jenkins examine the source code regularly to find changes. Jenkins also provides several build trigger options such as periodic building, SCM polling, and GitHub hook trigger for GITScm polling. A “quiet period” can also serve as a build trigger.

Manage credentials cautiously

API keys, user logins, and other sensitive information needed in Terraform execution should be properly secured. This may sound like a standard practice but it is worth emphasizing given the complexity of IaC management. Jenkins features a native credential storage system to securely store and manage sensitive information. The feature is under the “Manage Jenkins” tab. It encrypts the stored secrets so that they can be used without exposing the actual information.

The built-in credential store in Jenkins provides most of the functions needed for secure secrets storage. However, some users may prefer more advanced features for their specific needs, so they turn to plugins or external credential managers. These are necessary to have fine-grained control over the stored secrets, to integrate with identity providers especially those that use single sign-on (SSO) systems, and to deal with advanced secrets such as certificates and tokens. Also, organizations may need a better way to comply with regulatory requirements like the need for comprehensive audit trails in monitoring access to and changes in stored secrets. 

The hardcoding of credentials or secrets into scripts or configuration files should be strictly avoided. There are different ways to secure them in Jenkins, as indicated above. Also, credentials should be regularly rotated, even those that are secured under the Jenkins credential store function.

Embrace Pipeline-as-Code

It is advisable to implement the concept of pipeline-as-code, wherein pipelined job processes are defined with code. This code is then stored and version-controlled in a source repository. This makes it easy for Jenkins users to find, manage, and execute jobs for various source repositories and branches to avoid the necessity of manually creating and managing jobs whenever they are needed. This is also highly useful in collaborative projects.

In Jenkins, pipeline-as-code is implemented through the Jenkinsfile file stored in the repository root. The presence of Jenkinsfile in the root repository indicates the automatic management and execution of jobs according to repository branches. The file must have a Pipeline script, which contains the instructions for job execution, including the execution of multiple steps with coordinated parallel execution.

Pipeline-as-code does not only provide the benefits of replicability, consistency, and efficient version control. It also supports code modularity and the reuse of code components. Additionally, it bolsters pipeline visibility and transparency, which are essential in quickly finding and addressing issues. Moreover, it is a boon for security, compliance, and ease of maintenance.

In conclusion

Jenkins and Terraform are a potent team-up when it comes to infrastructure-as-code management. To make the most out of them, it helps to observe some best practices, particularly the ones briefly discussed above, to ensure robust and secure workflows.  Greater efficiency can be achieved through automatic triggering and pipeline-as-code, while security can be ensured with prudent credential or secrets management and the implementation of role-based access control.