Environment missing when using --mount=type=bind

[thernstig]

I have set a PATH in the nodejs builder below, but when I build the env outputs nothing.

FROM SLES as nodejs

WORKDIR /test
RUN mkdir bin
ENV PATH=/test/bin:${PATH}
ARG NODEJS_VERSION=20.10.0
ADD https://nodejs.org/dist/v${NODEJS_VERSION}/node-v${NODEJS_VERSION}-linux-x64.tar.gz node-v${NODEJS_VERSION}-linux-x64.tar.gz
RUN tar -xzf node-v${NODEJS_VERSION}-linux-x64.tar.gz \
    && rm node-v${NODEJS_VERSION}-linux-x64.tar.gz \
    && chown -R root:root node-v${NODEJS_VERSION}-linux-x64 \
    && ln -s ../node-v${NODEJS_VERSION}-linux-x64/bin/node bin/node \
    && ln -s ../node-v${NODEJS_VERSION}-linux-x64/bin/npm bin/npm \
    && ln -s ../node-v${NODEJS_VERSION}-linux-x64/bin/npx bin/npx

FROM nodejs as npm_builder

WORKDIR /test

RUN --mount=type=bind,source=packages/,target=packages/ \
    pwd \
    env \
    npm ci --workspace=packages/

I am trying to follow the best practice from here https://docs.docker.com/develop/develop-images/instructions/#add-or-copy:

RUN --mount=type=bind,source=requirements.txt,target=/tmp/requirements.txt \
    pip install --requirement /tmp/requirements.txt

The problem is that I have put the npm above in a special path, added to PATH to be able to run it without the full path to it, but it does not work. It says the following when builder the Dockerfile:

/bin/sh: npm: command not found

[profnandaa]

How was npm added on the path? And what happens when you specify the absolute path to npm instead?

[thernstig]

@profnandaa I have updated the example above to be more complete. If I specify an absolute path to /test/bin/npm it works.
If I docker run -it --rm test:latest bash into the build docker image, I can write env and see that it is set properly.