Where are the packages installed with `apt-get install` in Docker containers?

Question

I'm trying to locate the libgsl.so library in a Docker container after installing it successfully .

When I run an interactive shell with docker run -it container/image bash and try to find it find / -iname "*libgsl*" I get nothing (the tool tries to find it under /usr/lib/). It seems that the same is true for another successfully installed libraries (eg libjpeg62).

So, generally, where are these libraries being installed ?

I'm running Docker with VBox in MacOS. Here is the Dockerfile file:

FROM phusion/baseimage

# Install dependencies
RUN apt-get update && apt-get install -y \
  libgsl0ldbl \
  curl \
  gsl-bin

# Installs preseq from sources into /opt/
ENV PRESEQ_RELEASE=2.0
ENV PRESEQ_URL=http://smithlabresearch.org/downloads/preseq_linux_v${PRESEQ_RELEASE}.tar.bz2
ENV DEST_DIR=/opt/

# Download preseq; untar & decompress; remove tr.bz2 file; compile & install preseq; remove unnecessary files
RUN curl -SLo ${DEST_DIR}/preseq_v${PRESEQ_RELEASE}.tar.bz2 ${PRESEQ_URL} && \
  tar -xf ${DEST_DIR}/preseq_v${PRESEQ_RELEASE}.tar.bz2 -C ${DEST_DIR} && \
  rm -f ${DEST_DIR}/preseq_v${PRESEQ_RELEASE}.tar.bz2

ENV PATH=${DEST_DIR}/preseq_v${PRESEQ_RELEASE}:$PATH
CMD ["preseq"]

---

UPDATE

I was running the wrong container (not using the right tag) where I didn't have the library installed. After changing the tag, I found the libraries without a problem. Packages are installed in the default locations (in this case /usr/lib/).

Answer 1

Since phusion/baseimage use Ubuntu

Ask the package management what files the package contains:

dpkg -L libgsl0ldbl

This shows the files simply copied to those locations. These files are marked as managed by the package management