coc-docker

A practical first workflow

Use coc-docker for language assistance while editing Dockerfiles. It starts the bundled Dockerfile language server. This can help with instruction completion and diagnostics before a build; it does not build an image or check whether your application will run inside a container.

Check Dockerfile analysis without building an image

Run :CocInstall coc-docker, save this file as Dockerfile, and check :set filetype? reports dockerfile. The final line deliberately misspells an instruction:

Inspect :CocDiagnostics for an unknown-instruction message. Remove the RNU line and save; that message should clear. On a new line, type WO and trigger completion with your configured mapping to look for WORKDIR. Remove the temporary line after checking.

This file is only a language-service probe. The scratch image contains no shell or application, so using it to test a shell command or a runnable application would answer a different question. A successful editor check does not validate registry access, build context, copied paths or runtime dependencies.

If neither feature works, check docker.enable and inspect the Docker language-server output through :CocCommand workspace.showOutput. If your Dockerfile has a custom name, inspect filetype detection first. For Compose YAML, verify the provider for YAML separately rather than assuming Dockerfile support covers it.

Checked against coc-docker 1.0.2 and the Dockerfile language server. The operations above describe expected editor results, not an image build test.

Site-authored guidance reviewed on 2026-09-11. Content sources and maintainers · Choose extension responsibilities