LibSodium dependency in CMake doesn't resolve in Docker container

Question

I'm trying to build my C project using Docker and CMake. CMake'ing using cmake . && cmake --build . works fine on my system (MacOS), using the following CMakeLists.txt:

cmake_minimum_required (VERSION 3.0)
project (PROJECTNAME)

# Include libsodium
list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake/modules")
find_package(sodium REQUIRED)

include_directories(include)
file(GLOB SOURCES "src/*.c")

set(LIBRARY_OUTPUT_PATH "build")

add_library(project STATIC ${SOURCES})
target_link_libraries(project sodium)

The Findsodium.cmake, required by find_package(sodium REQUIRED) is a direct copy of the file on the libsodium GitHub.

Now I'm trying to build this using docker build and the following Dockerfile (I know some packages it installs are redundant):

FROM ubuntu:16.04
COPY . /project
RUN apt-get update && apt-get -y install \
  build-essential \
  cmake \
  libsodium18 \
  curl
RUN cd project && cmake .
RUN cmake --build .

Unfortunately this fails with the following message:

CMake Error at /usr/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
  Could NOT find sodium (missing: sodium_LIBRARY_RELEASE sodium_LIBRARY_DEBUG
  sodium_INCLUDE_DIR)
Call Stack (most recent call first):
  /usr/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
  cmake/modules/Findsodium.cmake:226 (find_package_handle_standard_args)
  CMakeLists.txt:8 (find_package)

When I run a normal docker container and perform the steps manually the same error is thrown. Somehow libsodium can not be located, even though it is properly installed:

$ ldconfig -p | grep sodium
libsodium.so.18 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libsodium.so.18

Anyone with experience using Findsodium.cmake on Ubuntu, or other, that can give some insight?

EDIT: after the suggestion of LinPy I added libsodium-dev as a package to be installed and the error changes slightly:

CMake Error at /usr/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
  Could NOT find sodium (missing: sodium_LIBRARY_RELEASE
  sodium_LIBRARY_DEBUG) (found version "

  #ifndef sodium_version_H

  #define sodium_version_H



  #include "export.h"



  #define SODIUM_VERSION_STRING "1.0.8"

  ...
  ...

  ")
Call Stack (most recent call first):
  /usr/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
  cmake/modules/Findsodium.cmake:226 (find_package_handle_standard_args)
  CMakeLists.txt:8 (find_package)

It seems that some things could be found now, but not the debug and release library?

Dockerfile looks like this now:

FROM ubuntu:16.04
COPY . /project
RUN apt-get update && apt-get -y install \
  build-essential \
  cmake \
  libsodium18 \ # also tried it without this line
  libsodium-dev \
  curl
RUN cd project && cmake .
RUN cmake --build .

EDIT 2: Adding pkg-config as well fixes the second error.

Answer 1

add this to your dockerfile:

RUN apt-get install -y libsodium-dev pkg-config