Docker produces incorrect ENTRYPOINT command

Question

I'm trying to build docker image for my application but I can't run container based on this image because of failing ENTRYPOINT execution:

User.Name@pc-name MINGW64 ~
$ docker run some-repository.com/application-name:latest
/bin/sh: line 0: [: missing `]'

There is my Dockerfile:

FROM some-repository.com/openjdk:11.0.5-jre-slim as build
FROM some-repository.com/rhel7-atomic

COPY --from=build /usr/local/openjdk-11 jx/

LABEL Team="some-team"
LABEL AppVersion=1111

RUN mkdir -p id
COPY application-name-1.6.17-SNAPSHOT.jar id

EXPOSE 26000

ENTRYPOINT [ "sh", "-c", "exec echo hello \$JAVA_OPTS \
    world"]

There is result of docker inspect :

"Cmd": [
    "/bin/sh",
    "-c",
    "#(nop) ",
    "ENTRYPOINT [\"/bin/sh\" \"-c\" \"[ \\\"sh\\\", \\\"-c\\\", \\\"exec echo hello \\\\$JAVA_OPTS     world\\\"]\"]"
],
"ArgsEscaped": true,
"Entrypoint": [
    "/bin/sh",
    "-c",
    "[ \"sh\", \"-c\", \"exec echo hello \\$JAVA_OPTS     world\"]"
]

Looks like ENTRYPOINT command was interpolated incorrectly and [ character was added to the command.

Why this problem appears and how can I fix it?

Answer 1

Remove the escape in front of the $ , it's an invalid escape in json and when the string doesn't parse as json it gets parsed as a string passed to a shell.

ENTRYPOINT [ "sh", "-c", "exec echo hello $JAVA_OPTS \
    world"]

If you wanted echo to print a $ , rather than having sh expand the variable, then you'd need a double escape to escape the escape character, so that json would pass a single \\ to the command being run:

ENTRYPOINT [ "sh", "-c", "exec echo hello \\$JAVA_OPTS \
    world"]