Rust rocket.rs not launching properly in Docker Container - docker

Question

I'm trying to build a docker image of a Rocket application. I've followed the rust docker documentation to make an image with a builder, but the resulting container wont launch the application.
Dockerfile
FROM rust:latest as builder
COPY ./id_rsa* /root/.ssh/
RUN chmod 600 /root/.ssh/id_rsa
RUN git config --global user.name "Runner"
RUN git config --global user.email "some#email.com"
RUN ssh-keyscan -t rsa gitlab.com >> ~/.ssh/known_hosts
RUN rustup default nightly
WORKDIR /usr/src/api
COPY ./api .
VOLUME /redis
RUN cargo install --path .
# ---
FROM debian:buster
ENV ROCKET_DATABASES={redis={url="redis://redis:6379/"}}
COPY --from=builder /usr/local/cargo/bin/api /usr/local/bin/api
EXPOSE 8000
CMD api
This is the dockerfile I expect to work, but instead results in a 'hanging' container. To be more percise the container runs with no console output.
I have connected to the resulting container and verified that the executable is being copied over properly and that it runs as expected in the container's shell. I can even get it to launch properly by removing the second stage, but this isn't ideal as it leaves SSH keys in the container.
Working Dockerfile
FROM rust:latest as builder
COPY ./id_rsa* /root/.ssh/
RUN chmod 600 /root/.ssh/id_rsa
RUN git config --global user.name "Runner"
RUN git config --global user.email "some#email.com"
RUN ssh-keyscan -t rsa gitlab.com >> ~/.ssh/known_hosts
RUN rustup default nightly
WORKDIR /usr/src/api
COPY ./api .
VOLUME /redis
RUN cargo install --path .
CMD /usr/local/cargo/bin/api