ko vs Skaffold

ko is an open-source builder for container images of Go applications. It runs `go build` locally, so Docker does not need to be installed. The project positions it for a single Go application with few operating-system base-image dependencies, such as one without cgo or OS package requirements. Builds can target all platforms supported by the configured base image or selected platforms such as linux/amd64 and linux/arm64. For Kubernetes, `ko resolve` builds images for `ko://` references in YAML and replaces those references with image references; `ko apply` can apply the resolved configuration. ko reuses the normal Go build cache and avoids pushing image blobs already present in the remote registry. It generates and uploads SPDX-format SBOMs by default, with an option to disable this. Registry credentials can come from Docker configuration, with built-in environment credential support for Google, Amazon, Azure, and GitHub container registries. A Terraform provider supports Infrastructure-as-Code workflows. ko supports Go applications only and defaults to CGO_ENABLED=0. Windows container image support is experimental and requires a Windows base image.

Skaffold is Google’s open-source project for building, pushing and deploying applications. It runs client-side and has no component installed on a cluster. In development mode, it watches source files and can rebuild images, synchronize files, test images and redeploy when changes are detected. Its command-line interface can build, test, render, apply, deploy and clean application artifacts. Listed capabilities include policy-based image tagging, resource port-forwarding, logging and file syncing. Builder integrations include Docker, Jib, Bazel, custom builders, Buildpacks and ko. Deployment options include kubectl, kpt, Helm, Docker, Google Cloud Run, Kustomize and Render. Cloud Code provides extensions for Visual Studio Code and JetBrains IDEs. Skaffold supports Linux, macOS and Windows and is listed at free as an open-source project with standalone CLI and IDE integrations. It checks Google servers for updates by default, although that check can be disabled. Installation documentation says anonymized usage data is collected with an opt-out. Its gRPC server is not compatible with HTTPS.