在Docker容器内非交互地解密gpg文件

Question

I am trying to decrypt a gpg file inside a docker container. Roughly speaking the Dockerfile does basic stuff:

FROM myimage
RUN ...
...
COPY docker-entrypoint.sh /entrypoint
RUN chmod u+x /entrypoint

The docker-entrypoint.sh contains:

gpg --decrypt --passphrase=${PASSWORD} /path/to/encrypted/file > /path/to/unencrypted/file
...
exec "$@"

I'm doing:

docker build -t "myimage" .
docker run -e PASSWORD -ti myimage

And I am getting:

gpg: directory `/root/.gnupg' created
gpg: new configuration file `/root/.gnupg/gpg.conf' created
gpg: WARNING: options in `/root/.gnupg/gpg.conf' are not yet active during this run
gpg: keyring `/root/.gnupg/secring.gpg' created               
gpg: keyring `/root/.gnupg/pubring.gpg' created      
usage: gpg [options] --decrypt [filename]

…as an error. The password environment var is being passed correctly, and that same command runs correctly on my machine.

I have tried with gpg2 with no success.

Answer 1

I just discovered the issue:

gpg --decrypt --passphrase="${PASSWORD}" \
    /path/to/encrypted/file > /path/to/unencrypted/file

ie quotes should be used in order to the environment variable to be properly transformed to text.