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Custom Images

Harness provides the flexibility to use custom images in your IACM stage, which refers to individual Terraform plugin steps such as the terraform init step in an IaCM pipeline provision stage. This guide walks you through the process of creating your custom image and incorporating it into your Harness pipelines.

Create an image​

Harness allows you to create custom images based on a provided base image. This enables you to tailor the image to your specific needs and use it in your workflows.

Version lock-in

Once you create a custom image using our base image, it becomes version-locked. This means that if we release a new version of our base image, your custom image will not automatically update to the latest version. For instance, if you create an image today using our base image version "1.0.0" and we subsequently release version "1.1.0," your custom image will still be using version "1.0.0."

If your version is out-of-date, while it is unlikely to cause a pipeline failure, your current version may lack some features, be open to security vulnerabilities or run into compatibility issues. In such cases, follow the Mitigating versioning challenges section below:

Mitigating versioning challenges

To address this versioning challenge and ensure that your custom image stays up-to-date with our latest improvements and features, you can implement specific steps within your CI/CD pipelines. These steps may include periodically checking for updates to our base image and rebuilding the custom image as necessary. It's crucial to proactively monitor our releases and sync the custom images to take full advantage of the latest enhancements.

To help detect out-of-date versions, Harness log a warning if your image version is five versions behind the latest release.

Create a custom image​

The following example custom image includes the Harness Terraform Plugin (HTP) version and has the AWS kubectl and kustomize tools installed in the root image giving your steps access to them as needed.

FROM plugins/harness_terraform
RUN apk update
RUN apk add aws-cli
RUN aws --version
RUN curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
RUN install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl
RUN chmod +x kubectl
RUN mkdir -p ~/.local/bin
RUN mv ./kubectl ~/.local/bin/kubectl

Cloud v0.56 or later

For cloud environments, there was a change in version 0.56 and later images where the user is no longer root. If you need the image to use the root user, please use the following code:

    FROM plugins/harness_terraform_vm:0.62.0
    RUN curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
    RUN unzip awscliv2.zip
    RUN ./aws/install
    RUN aws --version
    RUN curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
    RUN install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl
    RUN chmod +x kubectl
    RUN mkdir -p ~/.local/bin
    RUN mv ./kubectl ~/.local/bin/kubectl
    RUN curl -LO "https://github.com/kubernetes-sigs/kustomize/releases/download/kustomize%2Fv5.3.0/kustomize_v5.3.0_linux_amd64.tar.gz" \
        && tar xzf kustomize_v5.3.0_linux_amd64.tar.gz \
        && mv kustomize /usr/local/bin/kustomize \
        && rm kustomize_v5.3.0_linux_amd64.tar.gz

Use your own image​

To use your custom image in a step, create a reference in the YAML configuration indicating that the step should use your image.

- step:
    type: IACMTerraformPlugin
    name: apply
    identifier: apply
    timeout: 2h
    spec:
        command: apply
        image: plugins/private_harness_terraform_plugin  # (1)
        connectorRef: privateConnector  # (2)
info

In this example, the image attribute (1) in the YAML points to the plugin image in the Elastic Container Registry (ECR) where it is hosted. If your image is hosted in a private ECR, you'll need to create a connector for that ECR and define the connectorRef (2) for the connector. This ensures that Harness can access the image. At this stage, the "apply" step in your pipeline will use the "private_harness_terraform_plugin" and have access to kubectl and kustomize for its operations.

IACM execution-config​

To use images from your repository in an IACM stage, you can use the execution-config API endpoints.

note

Although some images mentioned here are also used by CI, it's important to note that any overrides specified using the IACM execution-config APIs are not applied to CI stages and vice versa. The images that can be overridden are:

  • harness/ci-addon.
  • harness/ci-lite-engine.
  • harness/drone-git.
  • plugins/harness_terraform.

Set your Images with the update-config endpoint:

curl \
-X POST \
-H 'x-api-key: <pat>' \
'https://app.harness.io/gateway/iacm-manager/execution-config/update-config?accountIdentifier=<account>&infra=k8' \
--header 'Content-Type: application/json' \
--data-binary @- << EOF
[
    {
        "field": "addonTag",
        "value": "<your_repo>/ci-addon:1.16.44"
    },
    {
        "field": "liteEngineTag",
        "value": "<your_repo>/ci-lite-engine:1.16.37"
    },
    {
        "field": "gitCloneTag",
        "value": "<your_repo>/drone-git:1.5.0-rootless"
    },
    {
        "field": "IACMTerraformTag",
        "value": "<your_repo>/harness_terraform:latest"
    }
]
EOF