> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/continuous-integration/use-harness-ci/migrate-to-harness-ci/migrating-from-jenkins.md). # Migrate from Jenkins CI to Harness CI Harness CI and Jenkins both allow you to create pipelines that automatically build, test, publish, release, and deploy code. This guide describes the important differences between Harness CI and Jenkins so that you can migrate your existing Jenkins pipelines to Harness CI. ### What makes Harness CI unique? Harness CI provides proprietary technologies, like Cache Intelligence and Test Intelligence, which make Harness CI [four times faster](https://harness.io/blog/fastest-ci-tool) than other leading CI tools. * Harness [Test Intelligence (TI)](/continuous-integration/use-harness-ci/use-harness-ci/run-tests/ti-overview.md) is a proprietary technology that accelerates test cycles by running only the tests necessary to confirm the quality of the code changes that triggered a build. Visualizations show which code changes caused which tests to be selected, and TI can help you identify gaps in your test plan. TI also detects negative trends and provides actionable insights to improve quality. With TI, it's possible to reduce build cycle times by up to 90% without compromising application quality. * Harness [Cache Intelligence](/continuous-integration/use-harness-ci/use-harness-ci/caching-ci-data/cache-intelligence.md) is a proprietary technology that reduces pipeline execution time by automatically caching well-known directories for languages like Java and Node.js. In addition, you can [use plugins](/continuous-integration/use-harness-ci/use-harness-ci/use-drone-plugins/explore-ci-plugins.md) to include GitHub Actions, Bitrise Workflow Steps, Jira updates, and more in your Harness CI pipelines. Harness CI is part of The [Harness Platform](/harness-ai/new-to-harness-platform/overview.md), which is a self-service CI/CD platform that enables end-to-end software delivery. The Harness Platform includes features, functionality, and additional modules to help you build, test, deploy, and verify software. For example: * [Secrets management](/harness-ai/use-harness-platform/secrets/secrets-management.md) through the [Harness secrets manager](/harness-ai/use-harness-platform/secrets/secrets-management/harness-secret-manager-overview.md) or an [external secrets manager](/harness-ai/troubleshooting-and-resources/tutorials/add-secrets-manager.md). * Role-Based Access Control (RBAC) helps you control user and group access to Harness resources according to users' roles. Using RBAC increases security and improves efficiency. * Harness Policy as Code is a centralized policy management and rules service that leverages the Open Policy Agent (OPA) to meet compliance requirements across software delivery and enforce governance policies. * The Harness Enterprise Ready Self-Managed Edition is an end-to-end solution for continuous, self-managed delivery. You can install and update Harness Self-Managed Enterprise Edition using online or offline (air-gapped) methods. ### Comparison: Pipeline architecture Both Harness CI and Jenkins use pipelines to organize builds. In both products, pipelines are made up of one or more stages, which represent major segments of the workflow. Each stage includes one or more steps, which in turn contain individual commands. In Jenkins, pipelines are defined using either Declarative or Scripted Pipeline syntax in a `Jenkinsfile`. In Harness CI, pipelines are defined in YAML and can be stored inline or in Git repositories. The following truncated examples provide a simple comparison of stage and step structure in Jenkins and Harness CI. {% tabs %} {% tab title="Jenkins" %} ```groovy pipeline { agent any stages { stage('Build') { steps { sh 'echo "Building on default agent"' } } } } ``` {% endtab %} {% tab title="Harness" %} ```yaml - stage: name: Build ... steps: - step: type: Run name: build identifier: build spec: connectorRef: my-docker-hub-connector image: maven:3.8-openjdk-17 shell: Bash command: echo "Building on Harness" ``` {% endtab %} {% endtabs %} For more information about Harness terminology, features, and pipeline components, go to the [CI key concepts](/continuous-integration/new-to-harness-ci/key-concepts.md). #### Stages and steps Stages in Jenkins are similar to stages in Harness CI. In both products, stages contain steps with commands. An important difference is that Jenkins Declarative Pipeline runs stages sequentially by default (unless using `parallel` blocks), similar to Harness CI where stages and steps also run sequentially by default. However, you can enable [parallelism and other looping strategies](#comparison-matrix-and-parallelism) in Harness CI. {% hint style="info" %} **ROOT AND NON-ROOT USERS** Steps run as the root user, generally. For example, with Harness Cloud build infrastructure, steps run directly on the host and, therefore, run as the root user. For services running on containers (which are steps where you specify a **Container Registry** and **Image** to use to execute the step's commands), you can use the **Run as User** setting to specify a user to use for that container. With Kubernetes cluster build infrastructure, you can use the **Run as User** setting to specify a user to use for individual steps, or you can [set a default user for all steps](/continuous-integration/use-harness-ci/use-harness-ci/set-up-build-infrastructure/k8s-build-infrastructure/set-up-a-kubernetes-cluster-build-infrastructure.md#run-as-non-root-or-a-specific-user) and then override the default user as needed for individual steps. {% endhint %} #### Scripts in pipelines Both Harness CI and Jenkins support running scripts or shell commands in steps. In Jenkins, you use `sh`, `bat`, or `powershell` steps to run scripts. In Harness CI, scripts are supplied in the `command` key, and can be supplied for any step type that supports `command`. You specify the shell type using the `shell` key. #### Writing pipelines Jenkins pipelines are written in Groovy-based DSL (either Declarative or Scripted syntax) and are stored in a `Jenkinsfile` in your code repository. Harness CI pipelines are written in YAML, and Harness provides you a choice of inline pipeline storage or [importing pipelines from Git](/harness-ai/use-harness-platform/git-experience/import-a-pipeline.md). Harness also provides both visual and code-based pipeline editors. * The Harness YAML editor includes schema validation and auto-complete recommendations to simplify and expedite pipeline configuration. * The Harness visual editor provides a guided experience that enables anyone to easily build, debug, and run pipelines. * You can switch back and forth between editors.
Complete pipeline comparison Here are examples of complete pipelines in Jenkins and Harness CI. pipeline { agent any environment { POSTGRES\_USER = 'postgres' POSTGRES\_PASSWORD = credentials('postgres-password') POSTGRES\_DB = 'postgres' } stages { stage('Build') { agent { docker { image 'openjdk:17.0-jdk' } } steps { sh 'echo "Building on openjdk"' } } stage('Test') { agent { docker { image 'node:13.0.0' } } steps { sh ''' echo "project level var: ${PROJ\_VAR}" echo "pipeline var: ${PIPELINE\_VAR}" echo "secret example: ${DB\_PASSWORD}" ''' } } stage('Matrix Build') { matrix { axes { axis { name 'PLATFORM' values 'windows', 'mac', 'linux' } } stages { stage('Build Platform') { steps { sh 'echo "Testing on ${PLATFORM}"' } } } } } }}pipeline: name: jenkins migration test identifier: jenkins\_migration\_test projectIdentifier: jenkins\_test orgIdentifier: default tags: {} stages: - stage: name: Build identifier: build type: CI spec: cloneCodebase: true execution: steps: - step: type: Background name: Background\_1 identifier: Background\_1 spec: connectorRef: YOUR\_IMAGE\_REGISTRY\_CONNECTOR image: postgres:10.8 envVariables: POSTGRES\_USER: postgres POSTGRES\_PASSWORD: <+secrets.getValue("DbPasswordSecret")> POSTGRES\_DB: postgres - step: type: Run name: build identifier: build spec: connectorRef: myDockerHubConnector image: openjdk:17.0-jdk shell: Bash command: echo "Building on openjdk" platform: os: Linux arch: Amd64 runtime: type: Cloud spec: {} - stage: name: Test identifier: test type: CI spec: cloneCodebase: true execution: steps: - step: type: Run name: test identifier: test spec: connectorRef: myDockerHubConnector image: node:13.0.0 shell: Bash command: |- echo "pipeline var:" <+pipeline.variables.pipelinevar1> echo "project level var:" <+variable.proj\_var> echo "secret example:" <+secrets.getValue("DbPasswordSecret")> platform: os: Linux arch: Amd64 runtime: type: Cloud spec: {} variables: \[] - stage: name: matrix stage identifier: matrix\_stage type: CI spec: cloneCodebase: true execution: steps: - step: type: Run name: platform\_test identifier: platform\_test spec: shell: Bash command: echo "Testing on <+matrix.platform>" failureStrategies: \[] platform: os: Linux arch: Amd64 runtime: type: Cloud spec: {} strategy: matrix: platform: - windows - mac - linux maxConcurrency: 3 properties: ci: codebase: connectorRef: account.myscm repoName: test build: <+input> variables: - name: pipelinevar1 type: String description: "" value: someval
### Comparison: Specify a Docker image In Jenkins, you can specify Docker images using the `agent` directive with a `docker` block, for example: ```groovy pipeline { agent { docker { image 'openjdk:17.0-jdk' } } stages { stage('Build') { steps { sh 'echo "Running in Docker container"' } } } } ``` In Harness CI, you specify *connectors* and images for each step, if necessary. Depending on the step type, the commands you are running, and your build infrastructure, you may not need to specify an image. For example, if a binary is already available on your build farm, you may not need to pull an image for that binary. For example, the following step includes a `connectorRef` referencing a Docker connector. [Docker connectors](/harness-ai/use-harness-platform/connectors/cloud-providers/ref-cloud-providers/docker-registry-connector-settings-reference.md) are platform-agnostic and can be used to connect to any Docker container registry. ```yaml - step: type: Run name: build identifier: build spec: connectorRef: my-docker-hub-connector image: openjdk:17.0-jdk shell: Bash command: echo "Running in Docker container" ``` {% hint style="info" %} **WHAT ARE CONNECTORS?** Harness integrates with many different types of repositories and providers. A connection from Harness to other platforms is called a [connector](/harness-ai/use-harness-platform/connectors.md). Connectors can connect to source control providers, cloud providers, container registries, and more. {% endhint %} ### Comparison: Define a multi-stage pipeline Both Jenkins and Harness CI execute pipeline stages in a specific order based on the configuration. {% tabs %} {% tab title="Jenkins" %} ```groovy pipeline { agent any stages { stage('Test') { steps { sh 'run tests' } } stage('Build') { steps { sh 'run build' } } stage('Deploy') { steps { sh 'deploy application' } } } } ``` {% endtab %} {% tab title="Harness" %} ```yaml stages: - stage: name: Test ... - stage: name: Build ... - stage: name: Deploy ... ``` {% endtab %} {% endtabs %} The following examples compare Jenkins and Harness CI pipelines with multiple stages.
YAML examples: Multi-stage pipelines pipeline { agent any stages { stage('Test') { agent { docker { image 'golang:latest' } } steps { sh 'go fmt $(go list ./... | grep -v /vendor/)' sh 'go vet $(go list ./... | grep -v /vendor/)' sh 'go test -race $(go list ./... | grep -v /vendor/)' } } stage('Build') { agent { docker { image 'golang:latest' } } steps { sh 'mkdir -p mybinaries' sh 'go build -o mybinaries ./...' } post { success { archiveArtifacts artifacts: 'mybinaries/\*\*' } } } }} stages: - stage: name: test identifier: test description: "" type: CI spec: cloneCodebase: true platform: os: Linux arch: Amd64 runtime: type: Cloud spec: {} execution: steps: - step: type: Run name: test-step identifier: teststep spec: shell: Sh command: | go fmt $(go list ./... | grep -v /vendor/) go vet $(go list ./... | grep -v /vendor/) go test -race $(go list ./... | grep -v /vendor/) - stage: name: build identifier: build type: CI spec: cloneCodebase: true platform: os: Linux arch: Amd64 runtime: type: Cloud spec: {} execution: steps: - step: type: Run name: build-step identifier: buildstep spec: shell: Sh command: | mkdir -p mybinaries go build -o mybinaries ./... sharedPaths: - mybinaries
### Comparison: Environment variables In Jenkins, you can use environment variables to control the behavior of stages and pipelines, store values you want to reuse, or avoid hard-coding values in your `Jenkinsfile`. You can use predefined environment variables (like `BUILD_NUMBER`, `JOB_NAME`), define custom variables in the `environment` block, or use credentials. This range of variable definition is also possible in Harness CI. In addition to built-in variables, you can define variables within individual pipelines, stages, and steps as well as at the project, organization, and account levels. {% tabs %} {% tab title="Jenkins" %} This Jenkins example demonstrates use of pre-defined and custom variables. ```groovy pipeline { agent any environment { MY_VAR = 'my-value' DB_PASSWORD = credentials('db-password-credential') } stages { stage('Test') { steps { sh 'echo "Build Number: ${BUILD_NUMBER}"' sh 'echo "Custom Var: ${MY_VAR}"' sh 'echo "Secret: ${DB_PASSWORD}"' } } } } ``` {% endtab %} {% tab title="Harness" %} To reference project, organization, and account variables, you use variable expressions formatted as: `<+variable.[scope].[variable_id]>`. Here are the syntax formats for variables declared at different levels: * Account-level variable reference: `<+variable.account.[var_id]>` * Organization-level variable reference: `<+variable.org.[var_id]>` * Project-level variable reference: `<+variable.[var_id]>` In this example, a step references a project-level environment variable called `ENV_VAR`. ```yaml - step: type: Run name: test-variable identifier: test_variable spec: command: echo "environment variable: " <+variable.env_var> ``` Within a single pipeline, you can define variables at the step, stage, and pipeline levels. For example, this step includes environment variable definitions. ```yaml - step: type: Background name: Background_1 identifier: Background_1 spec: connectorRef: YOUR_IMAGE_REGISTRY_CONNECTOR image: postgres:10.8 envVariables: POSTGRES_USER: postgres POSTGRES_PASSWORD: <+secrets.getValue("DbPasswordSecret")> POSTGRES_DB: postgres ``` To learn more about defining and fetching variables go to: * [Use Harness expressions](/harness-ai/use-harness-platform/variables-and-expressions/harness-variables.md) * [Define variables](/harness-ai/use-harness-platform/variables-and-expressions/add-a-variable.md) {% endtab %} {% endtabs %} ### Comparison: Matrix and parallelism In Jenkins, you can use the `matrix` directive for matrix builds and `parallel` blocks for parallel execution. In Harness CI, steps and stages run sequentially unless you enable parallelism. For example, this Harness CI YAML example shows a pipeline with two stages that run in parallel, as indicated by `- parallel`, and two stages that run sequentially after the two parallel stages. ```yaml stages: - parallel: - stage: name: Stage1 ... - stage: name: Stage2 ... - stage: name: Stage3 ... - stage: name: Stage4 ... ``` In addition to parallelism, you can use Harness CI's [looping strategies](/harness-ai/use-harness-platform/pipelines/looping-strategies/looping-strategies-matrix-repeat-and-parallelism.md) to make your pipelines more dynamic and versatile. These strategies allow your pipelines to execute the same set of tasks multiple times for several different configurations without requiring you to intentionally create unique steps or stages for each iteration. This is achieved by mentioning user-defined tags and referencing them in the pipeline using the following expression syntax: `<+matrix.usertag>` As in Jenkins, you also can combine parallelism and matrix strategies in Harness CI, as shown in the following examples. {% tabs %} {% tab title="Jenkins" %} ```groovy pipeline { agent any stages { stage('Matrix Build') { matrix { axes { axis { name 'PLATFORM' values 'windows', 'mac', 'linux' } } stages { stage('Test') { steps { sh 'echo "Testing on ${PLATFORM}"' } } } } } } } ``` {% endtab %} {% tab title="Harness" %} The following example describes a stage in a Harness CI pipeline that includes one step with matrix and parallelism strategies. The looping strategies are defined in `strategy` at the stage level. One matrix strategy, called `testparam`, is defined in `matrix` and parallelism is defined by `maxConcurrency: 3`. The script in the `Run` step calls the inputs from the matrix strategy by using the expression `<+matrix.testparam>`. ```yaml stages: - stage: name: Stage1 identifier: Stage1 type: CI spec: cloneCodebase: true execution: steps: - step: type: Run name: step1 identifier: step1 spec: connectorRef: dockerconectorref image: dockerimage:tag shell: Bash command: echo "Testing on <+matrix.testparam>" strategy: matrix: testparam: - node - python - ubuntu maxConcurrency: 3 ``` {% endtab %} {% endtabs %} ### Comparison: Triggers Both Jenkins and Harness CI support various methods to trigger pipeline execution. In Jenkins, pipelines can be triggered through: * SCM polling * Webhooks * Timer/cron triggers (using `triggers { cron(...) }`) * Manual triggers * Upstream/downstream project triggers Harness CI supports webhook, artifact, manifest and schedule triggers. The two most commonly used triggers are webhook triggers based on Git events and scheduled triggers based on `cron` expressions. To learn more about creating a trigger, go to [Triggers](/harness-ai/use-harness-platform/triggers.md). {% tabs %} {% tab title="Jenkins" %} ```groovy pipeline { agent any triggers { cron('45 13 * * 2') pollSCM('H/5 * * * *') } stages { stage('Build') { steps { sh 'echo "Building..."' } } } } ``` {% endtab %} {% tab title="Harness" %} ```yaml trigger: name: scheduled build identifier: scheduled_build enabled: true orgIdentifier: default projectIdentifier: JenkinsCI pipelineIdentifier: Demo source: type: Scheduled spec: type: Cron spec: expression: 45 13 * * 2 inputYaml: | pipeline: identifier: Demo properties: ci: codebase: build: type: branch spec: branch: main ``` {% endtab %} {% endtabs %} ### Comparison: Plugins and shared libraries Jenkins uses plugins and shared libraries to extend functionality. Harness CI uses plugins to add functionality to pipelines. In Jenkins, you can: * Install plugins through the Jenkins Plugin Manager * Use shared libraries for reusable pipeline code * Use community-contributed plugins for various integrations In Harness CI: * You can [use plugins](/continuous-integration/use-harness-ci/use-harness-ci/use-drone-plugins/explore-ci-plugins.md) to include GitHub Actions, Bitrise Workflow Steps, Jira updates, and more * Drone plugins are supported natively * Custom plugins can be created using Docker containers ### Comparison: Agents and build infrastructure In Jenkins, you define where jobs run using `agent` directives, which can specify: * `any` - Run on any available agent * `none` - No global agent; each stage must define its own * `label` - Run on an agent with a specific label * `docker` - Run inside a Docker container * `kubernetes` - Run in a Kubernetes pod In Harness CI, you configure the build infrastructure at the stage level using the `platform` and `runtime` settings. Harness supports several build infrastructure options: * **Harness Cloud**: Harness-managed infrastructure * **Kubernetes cluster**: Your own Kubernetes cluster * **Local runner**: Docker runner on your own machine * **Self-managed VMs**: AWS, GCP, or Azure VMs {% tabs %} {% tab title="Jenkins" %} ```groovy pipeline { agent { kubernetes { yaml ''' apiVersion: v1 kind: Pod spec: containers: - name: maven image: maven:3.8.1-jdk-11 command: - cat tty: true ''' } } stages { stage('Build') { steps { container('maven') { sh 'mvn clean install' } } } } } ``` {% endtab %} {% tab title="Harness" %} ```yaml - stage: name: Build identifier: build type: CI spec: cloneCodebase: true platform: os: Linux arch: Amd64 runtime: type: Cloud spec: {} execution: steps: - step: type: Run name: maven-build identifier: maven_build spec: connectorRef: myDockerHubConnector image: maven:3.8.1-jdk-11 shell: Bash command: mvn clean install ``` {% endtab %} {% endtabs %} ### See also Review the following information before proceeding with migration: * [Harness CI pipeline creation overview](/continuous-integration/use-harness-ci/use-harness-ci/prep-ci-pipeline-components.md) * [Caching in Harness CI](/continuous-integration/use-harness-ci/use-harness-ci/caching-ci-data.md) * [Split tests in Run steps](/continuous-integration/use-harness-ci/use-harness-ci/run-tests/speed-up-ci-test-pipelines-using-parallelism.md) * [Harness Platform documentation](https://app.gitbook.com/s/3F2TpHXhur2QtQnORSM9/README)