Docker ENTRYPOINT With a Piped Command

I am trying to create a dockerfile that uses a combination of rtlamr and rtlamr-collect to collect information about my utility meters. I cannot get the ENTRYPOINT in docker to be rtlamr | rtlamr-collect.

Here's my dockerfile:

FROM golang:latest AS build
RUN CGO_ENABLED=0 GOOS=linux go install github.com/bemasher/rtlamr-collect@latest
RUN CGO_ENABLED=0 GOOS=linux go install github.com/bemasher/rtlamr@latest

# Use a multi-stage build to reduce our image size
FROM alpine:latest AS runtime
COPY --from=build /go/bin/rtlamr /usr/bin/rtlamr
COPY --from=build /go/bin/rtlamr-collect /usr/bin/rtlamr-collect

# Really wish this would just work as expected:
ENTRYPOINT ["rtlamr | rtlamr-collect"]

As a work around I have found that I can create a simple shell script and have that serve as the entry point, but that wasn't ideal because of the need for an extra file. I would not be opposed to a solution that somehow created the extra file on the fly however:

Working dockerfile:

FROM golang:latest AS build
RUN CGO_ENABLED=0 GOOS=linux go install github.com/bemasher/rtlamr-collect@latest
RUN CGO_ENABLED=0 GOOS=linux go install github.com/bemasher/rtlamr@latest

# Use a multi-stage build to reduce our image size
FROM alpine:latest AS runtime
COPY --from=build /go/bin/rtlamr /usr/bin/rtlamr
COPY --from=build /go/bin/rtlamr-collect /usr/bin/rtlamr-collect

# I cannot for the life of me get `rtlamr | rtlamr-collect` to work as entry
# point to work around this limitation I created this small shell script that
# basically does it, and set that as the entry point which works.
ADD run.sh /usr/bin/run.sh
RUN chmod 777 /usr/bin/run.sh
ENTRYPOINT ["/usr/bin/run.sh"]

Content of run.sh:

#!/bin/sh
rtlamr | rtlamr-collect

I believe a simple test case to play with might be something like this:

dockerfile:

FROM alpine:latest
ENTRYPOINT ["echo 'hello world' | grep ell"]

Attempting to run this shows:

docker: Error response from daemon: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: exec: "echo 'hello world' | grep ell": executable file not found in $PATH: unknown.

However if you login to the Docker Container Shell and perform the same command it works as expected:

/ # echo 'hello world' | grep ell
hello world

Depending on the complexity of the command you can embed it into the Dockerfile like this:

FROM alpine:latest

RUN \
    echo "#!/bin/ash" > /entrypoint.sh &&\
    echo "echo 'hello world' | grep ell" >> /entrypoint.sh &&\
    chmod 755 /entrypoint.sh

ENTRYPOINT ["/entrypoint.sh"]

Output:

PS C:\Users\me\Desktop\test> docker build -t test ./
PS C:\Users\me\Desktop\test> docker run -it test:latest
hello world

If you need something more elaborate let me know and I'll have another dig through my previous work.