RUN <<EOF without an interpreter and cachi2

[owtaylor]

RUN <<EOF
mkdir -p /etc/foo
cp -aR /src/foo /etc/foo
EOF

gets turned into:

RUN . /cachi2/cachi2.env && <<EOF
mkdir -p /etc/foo
cp -aR /src/foo /etc/foo
EOF

which is weirdly not a syntax error, but a no-op. The right transformation would be something like:

RUN . /cachi2/cachi2.env && /bin/sh <<EOF
mkdir -p /etc/foo
cp -aR /src/foo /etc/foo
EOF

Once you consider RUN --mount=type=bin,src=/a,dest=/b <<EOF wedging this into the current code gets a little tricky.

[chmeliik]

@owtaylor I would assume this is not critical since there is a fairly easy workaround (use /bin/sh <<EOF rather than just <<EOF)?

But we should fix this at some point. A good Dockerfile parser+editor will be needed.

[eskultety]

@owtaylor what is the benefit of using heredoc vs RUN cmd1 && cmd2 && cmdN? I agree that we need to support legitimate RUN options, but when it comes to heredoc I'm confused, does it serve a particular purpose in a Dockerfile or is it just a syntactic sugar?

[chmeliik]

Just came across https://www.mankier.com/1/cstrans-df-run (in kdudka/konflux-test-multicluster-global-hub@8899893)

It doesn't handle heredocs correctly either, but perhaps a contribution would be reasonable (it's a C++ codebase, haven't looked into it much)