Environment variable in ENTRYPOINT is not substituted with its value at runtime

[antonsergeyev]

Describe the bug
An environment variable used in ENTRYPOINT is not substituted with its value at runtime.

To Reproduce
Assume a dockerfile:

FROM alpine:latest
ENTRYPOINT echo ${MESSAGE}

Build it with docker (works as expected):

docker build -t makisu-echo-docker .
docker run -e MESSAGE=hello makisu-echo-docker
>hello

Build it with makisu (unexpected output):

makisu_build -t makisu-echo .
docker run -e MESSAGE=hello makisu-echo
>${MESSAGE} /bin/sh

Expected behavior
I expect ENTRYPOINT to change dynamically with respect to the environment variable.
The output above should be "hello".

Additional context
I'm using makisu 0.1.12 and docker 19.03.3

[ericmeadows]

This is also an issue that I am having!

[Rowern]

This bug may lie inside the lib/parser/dockerfile/replace_variables.go file but I might be mistaken.

I will take a look at this later this week.

EDIT: Not at all inside the replace_variables file.

[Rowern]

It looks like docker create the following Entrypoint:

[
  "/bin/sh",
  "-c",
  "echo ${MESSAGE}"
]

And makisu:

[
  "echo",
  "${MESSAGE}"
]

EDIT: A simple workaround until this is fixed is to use this syntax for the entrypoint: from the dockerfile ref

[Rowern]

Anothre PR to handle the CMD directive that also needs this mechanism: #323

[Rowern]

@yiranwang52 You can close this I think

[yiranwang52]

Yes, thanks for fixing this.