How do I use heredoc in a Makefile?

Question

How do I use heredoc in a Makefile? This Makefile is not functional:

EXECUTABLE=server

build: 
     docker build -t $(EXECUTABLE) - << EOF \
         FROM scratch \
         ADD bin/$(EXECUTABLE) /bin/$(EXECUTABLE) \
         CMD ["/bin/$(EXECUTABLE)"] \
     EOF

What is the simplest docker command that works on the command line, but doesn't work when you put it in a makefile? — Beta, May 17 '18 at 19:45
Don't try. Create a shell script wrapper around the command and call that. — reinierpost, May 18 '18 at 09:09
Possible duplicate of [Heredoc in a Makefile?](https://stackoverflow.com/questions/5873025/heredoc-in-a-makefile) — imz -- Ivan Zakharyaschev, Feb 04 '19 at 00:50

score 3 · Accepted Answer · answered May 19 '18 at 13:26

It looks like going over a file using heredocs inside a Makefile solves half of the problem:

build: Dockerfile
    docker build -t $(EXECUTABLE) .
    rm Dockerfile

.ONESHELL:
Dockerfile: 
    cat <<- EOF > $@
        FROM scratch
        ADD bin/$(EXECUTABLE) /bin/$(EXECUTABLE)
        CMD ["/bin/$(EXECUTABLE)"]
    EOF

Still, it would be nice to have it all inline.

How do I use heredoc in a Makefile?

1 Answers1