Carvel (CloudMonk.io)

Carvel



Carvel is an open-source project that offers a collection of reliable, single-purpose, and composable tools designed to streamline the building, configuration, and deployment of applications on Kubernetes. These tools are intended to simplify various aspects of the Kubernetes workflow, from templating and packaging to deployment and management, making it easier for developers and operators to work with Kubernetes resources.

Key Features



* **Templating and Configuration:** `ytt` (YAML Templating Tool) allows you to template and overlay Kubernetes YAML configurations, making it easier to customize and manage complex configurations.
* **Image Building and Management:** `kbld` (Kubernetes Image Builder) simplifies the process of building or referencing container images within Kubernetes configurations, promoting immutability and reproducibility.
* **Deployment and Management:** `kapp` (Kubernetes Application) provides a declarative way to deploy, upgrade, and delete multiple Kubernetes resources as a single application, ensuring consistency and simplifying rollbacks.
* **Packaging and Distribution:** `imgpkg` (Image Package) bundles and relocates application configuration and container images via Docker registries, facilitating distribution and deployment.
* **Other Tools:** Carvel also includes other useful tools, such as `vendir` for managing external dependencies and `secretgen-controller` for generating secrets based on templates.

Benefits



* **Simplified Configuration Management:** Carvel tools, especially `ytt` and `kustomize`, simplify the creation and management of complex Kubernetes configurations, making them more modular and reusable.
* **Improved Developer Experience:** The declarative approach and focus on composability make it easier for developers to work with Kubernetes resources and automate common tasks.
* **GitOps Compatibility:** Carvel tools align well with GitOps practices, where configuration changes are tracked and managed through Git repositories.
* **Extensibility:** The modular design of Carvel tools allows for easy integration and extension with other Kubernetes tools and workflows.

Code Examples



1. **Templating with `ytt`:**

```bash
ytt -f config.yaml -f values.yaml > output.yaml
```

This command uses `ytt` to template the `config.yaml` file with values from `values.yaml`, producing the final Kubernetes manifest in `output.yaml`.

2. **Deploying with `kapp`:**

```bash
kapp deploy -a my-app -f manifests/
```

This command uses `kapp` to deploy the Kubernetes resources defined in the `manifests/` directory as a single application named "my-app."

3. **Building Images with `kbld`:**

```bash
kbld -f deployment.yaml --imgpkg-lock-output image-locks.yaml
```

This command uses `kbld` to build or reference container images within the `deployment.yaml` file and generates an `image-locks.yaml` file that captures the exact image digests used, promoting immutability.

Additional Resources



* **Carvel Official Website:** [https://carvel.dev/](https://carvel.dev/)
* **Carvel GitHub Organization:** [https://github.com/carvel-dev](https://github.com/carvel-dev)