syntax highlighting problems with Dockerfiles

[aep-sunlife]

RUN is not the only Dockerfile directive that supports multiline statements with backslash (\). For example, ARG and potentially other directives also support this syntax. However, the Microsoft Docker VSCode plugin struggles to highlight multiline ARG instructions.

ARG supports declaring multiple variables in one instruction:

https://docs.docker.com/reference/dockerfile/#arg

However, the plugin doesn't consistently highlight the bindings in the same color.

Example:

ARG http_proxy_host \
    https_proxy_host \
    http_proxy_port \
    https_proxy_port \
    no_proxy

[bwateratmsft]

@rcjsuen for visibility

This could be a problem in the built-in vscode.docker extension which provides basic syntax highlighting. @aep-sunlife if you disable the Docker extension, which would leave only the built-in vscode.docker extension active, does the syntax highlighting look correct?

[rcjsuen]

This could be a problem in the built-in vscode.docker extension which provides basic syntax highlighting. @aep-sunlife if you disable the Docker extension, which would leave only the built-in vscode.docker extension active, does the syntax highlighting look correct?

What is the difference "built-in vscode.docker extension" vs "the Docker extension"? 🤔
Did you mean the default Dockerfile TextMate grammar that comes pre-installed with Visual Studio Code?

[bwateratmsft]

Yes, that's the one. The human-readable title for it is "Docker Language Basics"

[bwateratmsft]

@aep-sunlife can you also share a screenshot? When I try with the Docker extension both enabled and disabled, it is showing them the same color:

Enabled:

Disabled: