notepad++ syntax highlighting for Dockerfiles, store at something like C:\Users\[user]\AppData\Roaming\Notepad++\userDefineLangs\userDefineLang_Dockerfile.xml

userDefineLang_Dockerfile.xml

<NotepadPlus>
    <UserLang name="Dockerfile" ext="Dockerfile" udlVersion="2.1">
        <Settings>
            <Global caseIgnored="no" allowFoldOfComments="no" foldCompact="no" forcePureLC="1" decimalSeparator="0" />
            <Prefix Keywords1="no" Keywords2="yes" Keywords3="no" Keywords4="no" Keywords5="no" Keywords6="no" Keywords7="no" Keywords8="no" />
        </Settings>
        <KeywordLists>
            <Keywords name="Comments">00# 01 02 03 04</Keywords>
            <Keywords name="Numbers, prefix1"></Keywords>
            <Keywords name="Numbers, prefix2"></Keywords>
            <Keywords name="Numbers, extras1"></Keywords>
            <Keywords name="Numbers, extras2"></Keywords>
            <Keywords name="Numbers, suffix1"></Keywords>
            <Keywords name="Numbers, suffix2"></Keywords>
            <Keywords name="Numbers, range"></Keywords>
            <Keywords name="Operators1">= :- :+ : [ ] ,</Keywords>
            <Keywords name="Operators2"></Keywords>
            <Keywords name="Folders in code1, open"></Keywords>
            <Keywords name="Folders in code1, middle"></Keywords>
            <Keywords name="Folders in code1, close"></Keywords>
            <Keywords name="Folders in code2, open"></Keywords>
            <Keywords name="Folders in code2, middle"></Keywords>
            <Keywords name="Folders in code2, close"></Keywords>
            <Keywords name="Folders in comment, open"></Keywords>
            <Keywords name="Folders in comment, middle"></Keywords>
            <Keywords name="Folders in comment, close"></Keywords>
            <Keywords name="Keywords1">FROM MAINTAINER ENV RUN CMD ADD EXPOSE COPY ENTRYPOINT VOLUME USER WORKDIR ONBUILD LABEL ARG STOPSIGNAL HEALTHCHECK SHELL AS</Keywords>
            <Keywords name="Keywords2">$ ${</Keywords>
            <Keywords name="Keywords3">--platform --from --chown&#x000D;&#x000A;</Keywords>
            <Keywords name="Keywords4"></Keywords>
            <Keywords name="Keywords5"></Keywords>
            <Keywords name="Keywords6"></Keywords>
            <Keywords name="Keywords7"></Keywords>
            <Keywords name="Keywords8"></Keywords>
            <Keywords name="Delimiters">00&quot; 00&apos; 01\ 02&quot; 02&apos; 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23</Keywords>
        </KeywordLists>
        <Styles>
            <WordsStyle name="DEFAULT" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="COMMENTS" fgColor="008000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="LINE COMMENTS" fgColor="008000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="NUMBERS" fgColor="FF0000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS1" fgColor="0000FF" bgColor="FFFFFF" fontName="" fontStyle="1" nesting="0" />
            <WordsStyle name="KEYWORDS2" fgColor="FF8040" bgColor="FFFFD9" fontName="" fontStyle="1" nesting="0" />
            <WordsStyle name="KEYWORDS3" fgColor="008080" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS4" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS5" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS6" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS7" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS8" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="OPERATORS" fgColor="800000" bgColor="FFFFFF" fontName="" fontStyle="1" nesting="0" />
            <WordsStyle name="FOLDER IN CODE1" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="FOLDER IN CODE2" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="FOLDER IN COMMENT" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS1" fgColor="808080" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="2048" />
            <WordsStyle name="DELIMITERS2" fgColor="FF8040" bgColor="FFFFD9" fontName="" fontStyle="1" nesting="0" />
            <WordsStyle name="DELIMITERS3" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS4" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS5" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS6" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS7" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS8" fgColor="000000" bgColor="FFFFFF" fontName="" fontStyle="0" nesting="0" />
        </Styles>
    </UserLang>
</NotepadPlus>

Does someone know how to make Notepad++ automatically assign this theme to all files labelled Dockerfile? I have to manually select Language > Dockerfile each time I open a file, the highlighting is not applied automatically.

I know this is old, but as the question was never answered I'll answer it for future searchers like myself who come across it

Notepad++ uses extensions to automatically determine what Language to use, as Dockerfile has no extension, to my knowledge, it's beyond the scope of Notepad++ to be able to recognize it

@LostOnTheLine and any that follow on to reading this!

There is a Python Script plugin for Notepad++ and a plugin for that available as Mode Line which can do any, or all, of:

• Set the language based on any python fnmatch rule(s) that you set, e.g. fnmatch.fnmatch('dockerfile*'). If you add the script to your Notepad++ python scripts start-up entry then this will work for any matching filename, not just extension, without needing to change any of the files.
• Set the language, (built-in or custom), to use based on a shebang, e.g. #! /usr/bin/env docker or #! /usr/bin/env podman, on the first line of each file. It is not a bad practice to have a shebang in each of your files anyway.
• Set the language &/or other settings based on Vim modeline entries in the file. Only really works if you are also using vim!

If you install the Python script plug-in, then follow the steps for installing the Mode Line plugin, set it to run on start-up as described and then edit either, or both, of the sections of %appdata%\Local\Notepad++\plugins\PythonScript\lib\ModelineLanguageDetectors.py for file name based or shebang detection then restart Notepad++ it works very nicely.

I would like to add my thanks to Dominik @centic9 for the original language file, Francois Francois-R.Boyer@PolyMtl.ca for the Mode Line plugin, Dave @davegb3 for the Python Script Plugin and Don Ho @donho for Notepad++ all of the nearly 400 other contributors to Notepad++ and the Python community for all of their hard work and for their generosity in sharing their efforts with us all.