abn/heredoc-dockerfile.snip

maxx27 · 2022-09-02T12:08:21Z

Also, there is official way to do it:

# syntax=docker/dockerfile:1.3-labs

RUN <<EOF
echo "Hello" >> /hello
echo "World!" >> /hello
EOF

I use it as the following:

# syntax=docker/dockerfile:1.4
RUN cat <<EOF >> /usr/local/bin/startup.sh
if [ \$# -gt 0 ]; then
    exec "\$@"
else
    /usr/bin/tini -- /usr/local/bin/jenkins.sh
fi
EOF

daudo · 2024-06-16T22:01:41Z

kudos @maxx27! I was banging my head why in 2024 it still has to be so difficult to use heredocs in Dockerfiles in a reasonable way. That last snippet of yours is the way to go! Thanks!

image72 · 2024-07-31T06:26:01Z

FROM debian
RUN <<EOT bash
  set -eux
  to_install=(
    vim
  )
  apt-get update
  failing_command # set -e exit with non-zero status 
  apt-get install -y "\${to_install[@]}"
EOT

# execute list shell
RUN <<EOF
apt-get update
apt-get upgrade -y
apt-get install -y ...
EOF

# run python
RUN <<EOF
#!/usr/bin/env python3
with open("/hello", "w") as f:
    print("Hello", file=f)
    print("World", file=f)
EOF

# create index.html
COPY <<EOF /usr/share/nginx/html/index.html
<html>hello, index</html>
EOF

# create /etc/mysql/my.cnf
RUN <<-EOF > /etc/mysql/my.cnf
[mysqld]
user=root
datadir=/app/mysql
port=3306
log-bin=/app/mysql/mysql-bin
EOF

	#printf
	RUN printf '#!/bin/bash\n\
	echo hello world from line 1\n\
	echo hello world from line 2'\
	>> /tmp/hello

	#echo
	RUN echo -e '#!/bin/bash\n\
	echo hello world from line 1\n\
	echo hello world from line 2'\
	>> /tmp/hello

abn/heredoc-dockerfile.snip

maxx27 commented Sep 2, 2022

daudo commented Jun 16, 2024

image72 commented Jul 31, 2024