NCS: CMake unable to execute Python

[timonsku]

When I try to build any application with west I always get a CMake error complaining that it is unable to run the Python version included with the NCS toolchain.
The error log:
CMake Error at /usr/share/cmake-3.25/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find Python3 (missing: Interpreter) (Required is at least version
  "3.8")

      Reason given by package:
          Interpreter: Cannot run the interpreter "/home/timon/ncs/toolchains/7795df4459/usr/local/bin/python3"

I do not have any issues building application with mainline Zephyr targeting other SoCs. This is unique to NCS.
I followed the instructions for command line use over at https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/installation/install_ncs.html

The python installation does exist at the mentioned path but if you run it prints "error while loading shared libraries: libpython3.8.so.1.0: cannot open shared object file: No such file or directory"
So something seems very broken here.
I source the Zephyr environment via source ncs/zephyr/zephyr-env.sh before trying to build with west as I build from the command line.
Building using the shell launched by nrfutil toolchain-manager launch --shell does work but working from that shell is absolutely not an option. I would like to work in my own shell environment as I do with mainline Zephyr.
This feels like the environment loaded with zephyr-env.sh is incomplete.

NCS version: 2.5.0
OS: Ubuntu 22.04

[Jørgen Holmefjord]

Hi,

I tried to follow the same instructions on Ubuntu 22.04, but I'm not able to reproduce the behavior you are seeing.

Can you check that shared library is available? On my setup I see the following:

bash-5.1$ find /* -name "libpython3.8.so.1.0" -print 2>/dev/null
/home/joh2/ncs/toolchains/7795df4459/opt/nanopb/generator-bin/libpython3.8.so.1.0
/home/joh2/ncs/toolchains/7795df4459/usr/local/lib/libpython3.8.so.1.0

If you do not see this file, please try to reinstall the toolchain.

Best regards,
Jørgen

[timonsku]

That library is available at that location.
I assume the environment isn't loading correctly.
Could you tell me what steps you take from a terminal session to compiling one of the samples?

[JRPC]

I can reproduce the exact same issue. 

If I use west -build directly from my console, I get the following output:

-- west build: generating a build system
Loading Zephyr default modules (Zephyr base (cached)).
-- Application: /nrf/applications/Riverrock
-- CMake version: 3.22.2
-- Using NCS Toolchain 2.4.0 for building. (/root/ncs/toolchains/1f9b40e71a/cmake)
CMake Error at /usr/local/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
Could NOT find Python3 (missing: Interpreter) (Required is exact version
"3.8")

Reason given by package:
Interpreter: Cannot run the interpreter "/root/ncs/toolchains/1f9b40e71a/usr/local/bin/python3"

Call Stack (most recent call first):
/usr/local/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:594 (_FPHSA_FAILURE_MESSAGE)
/usr/local/share/cmake-3.22/Modules/FindPython/Support.cmake:3166 (find_package_handle_standard_args)
/usr/local/share/cmake-3.22/Modules/FindPython3.cmake:490 (include)
/zephyr/cmake/modules/python.cmake:46 (find_package)
/zephyr/cmake/modules/zephyr_default.cmake:115 (include)
/zephyr/share/zephyr-package/cmake/ZephyrConfig.cmake:66 (include)
/zephyr/share/zephyr-package/cmake/ZephyrConfig.cmake:97 (include_boilerplate)
CMakeLists.txt:11 (find_package)


-- Configuring incomplete, errors occurred!
FATAL ERROR: command exited with status 1: /usr/local/bin/cmake -DWEST_PYTHON=/opt/venv/bin/python3.8 -B/nrf/applications/Riverrock/build -GNinja -DBOARD=iotex_pebble_hw30ns -S/nrf/applications/Riverrock

if I try to use the nrfutil toolchain manager console, I get this:

-- west build: generating a build system
Loading Zephyr default modules (Zephyr base (cached)).
-- Application: /nrf/applications/Riverrock
-- CMake version: 3.20.5
-- Using NCS Toolchain 2.4.0 for building. (/root/ncs/toolchains/1f9b40e71a/cmake)
-- Found Python3: /root/ncs/toolchains/1f9b40e71a/usr/local/bin/python3 (found suitable exact version "3.8.2") found components: Interpreter
-- Cache files will be written to: /root/.cache/zephyr
-- Zephyr version: 3.3.99 (/zephyr)
-- Found west (found suitable version "1.0.0", minimum required is "0.7.1")
-- Board: iotex_pebble_hw30ns
-- Found host-tools: zephyr 0.16.0 (/root/ncs/toolchains/1f9b40e71a/opt/zephyr-sdk)
-- Found toolchain: zephyr 0.16.0 (/root/ncs/toolchains/1f9b40e71a/opt/zephyr-sdk)
-- Found Dtc: /root/ncs/toolchains/1f9b40e71a/usr/local/bin/dtc (found suitable version "1.4.7", minimum required is "1.4.6")
-- Found BOARD.dts: /nrf/boards/arm/iotex_pebble_hw30/iotex_pebble_hw30ns.dts
-- Generated zephyr.dts: /nrf/applications/Riverrock/build/zephyr/zephyr.dts
-- Generated devicetree_generated.h: /nrf/applications/Riverrock/build/zephyr/include/generated/devicetree_generated.h
-- Including generated dts.cmake file: /nrf/applications/Riverrock/build/zephyr/dts.cmake
Parsing /nrf/applications/Riverrock/Kconfig
/zephyr/scripts/kconfig/kconfig.py: /nrf/applications/Riverrock/Kconfig:64: '/nrf/applications/Riverrock/src/watchdog/Kconfig' not found (in 'rsource "src/watchdog/Kconfig"'). Check that environment variables are set correctly (e.g. $srctree, which is set to '/zephyr'). Also note that unset environment variables expand to the empty string.
CMake Error at /zephyr/cmake/modules/kconfig.cmake:339 (message):
command failed with return code: 1
Call Stack (most recent call first):
/nrf/cmake/modules/kconfig.cmake:29 (include)
/zephyr/cmake/modules/zephyr_default.cmake:115 (include)
/zephyr/share/zephyr-package/cmake/ZephyrConfig.cmake:66 (include)
/zephyr/share/zephyr-package/cmake/ZephyrConfig.cmake:97 (include_boilerplate)
CMakeLists.txt:11 (find_package)


-- Configuring incomplete, errors occurred!
FATAL ERROR: command exited with status 1: /root/ncs/toolchains/1f9b40e71a/usr/local/bin/cmake -DWEST_PYTHON=/root/ncs/toolchains/1f9b40e71a/usr/local/bin/python3.8 -B/nrf/applications/Riverrock/build -GNinja -DBOARD=iotex_pebble_hw30ns -S/nrf/applications/Riverrock

At first glance, I think the reason is that the console sets its own WEST_PYTHON path, and uses it's own CMAKE. 

The errors you see in the compilation using the shell are not important, it's my app's coding error, but the point is that this issue is valid - west build fails since by default it's looking in the toolchain by default for Python, which I think should not be the case, unless we are using the toolchain console

[timonsku]

thanks for reproducing that is very helpful to know that its not specific to my system

[JRPC]

I found that if I turn off the installation of the ncs toolchain, it works perfectly with the default builder using python with virtual environments. if I install NCS via toolchain manager, west defaults to using python installed by the toolchain manager, even if the console is not initiated. - and if you don't initialize the console before building, like `nrfutil toolchain-manager launch --shell`, then the build will fail, since the "default" West build still relies on the toolchain manager specified versions, even though the shell was not launched; and since the shell is not launched, it's missing some parameters set by the custom shell.

Instead of using the ncs shell, I use a Docker based solution, where I wrote a specific dockerfile for each individual type of custom firmware I want to build:

# Prepare the environment variables for building the firmware
FROM ubuntu:mantic
ENV DEBIAN_FRONTEND noninteractive
RUN rm /bin/sh && ln -s /bin/bash /bin/sh
ENV VIRTUAL_ENV=/opt/venv
ENV PATH="$VIRTUAL_ENV/bin:$PATH"

# Update image and install necessary packages
RUN apt update && apt install -y apt-utils
RUN apt upgrade -y
RUN apt install -y --no-install-recommends \
    openssl \
    wget \
    xz-utils \ 
    file \
    ninja-build \
    make \
    gcc \
    gcc-multilib \
    g++-multilib \
    libssl-dev \
    libsdl2-dev \
    dfu-util \
    git \
    flex \
    bison \
    bzip2 \
    udev \
    libxcb-render0 \
    libxcb-render-util0 \
    libxcb-shape0 \
    libxcb-icccm4 \
    libxcb-keysyms1 \
    libxcb-image0 \
    libxkbcommon-x11-0 \
    libfontconfig1 \
    libfreetype6 \
    ca-certificates

# Install packages manually, since they are not provided pre-packaged by the ubuntu repositories
RUN wget https://github.com/Kitware/CMake/releases/download/v3.22.2/cmake-3.22.2.tar.gz && \
    tar -zxvf cmake-3.22.2.tar.gz && \
    mv cmake-3.22.2 /opt/cmake && \
    cd /opt/cmake && \
    ./bootstrap && \
    make -j`nproc` && \
    make install && \
    rm /cmake-3.22.2.tar.gz

# Install GNU Arm Embedded Toolchain
RUN wget https://armkeil.blob.core.windows.net/developer/Files/downloads/gnu-rm/9-2020q2/gcc-arm-none-eabi-9-2020-q2-update-x86_64-linux.tar.bz2 && \
    tar -jxvf gcc-arm-none-eabi-9-2020-q2-update-x86_64-linux.tar.bz2 && \
    mv gcc-arm-none-eabi-9-2020-q2-update /opt/gnuarmemb && \
    rm /gcc-arm-none-eabi-9-2020-q2-update-x86_64-linux.tar.bz2

# Install dtc
RUN wget https://git.kernel.org/pub/scm/utils/dtc/dtc.git/snapshot/dtc-1.6.1.tar.gz && \
    tar -zxvf dtc-1.6.1.tar.gz && \
    mv dtc-1.6.1 /opt/dtc-1.6.1 && \
    cd /opt/dtc-1.6.1 && \
    make -j`nproc` && \
    make install && \
    rm /dtc-1.6.1.tar.gz 

# Install Python 3.8
RUN wget https://www.python.org/ftp/python/3.8.0/Python-3.8.0.tgz && \
    tar -zxvf Python-3.8.0.tgz && \
    cd Python-3.8.0 && \
    ./configure --enable-optimizations && \
    make -j`nproc` && \
    make install && \
    rm /Python-3.8.0.tgz

# Prepare Python virtual environment
RUN python3.8 -m venv $VIRTUAL_ENV
RUN python3.8 -m pip install --upgrade pip wheel
RUN python3.8 -m pip install --upgrade west tk setuptools setuptools-rust intelhex pyelftools docopt click cryptography cbor

# Install zephyr-sdk
RUN wget https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v0.16.1/zephyr-sdk-0.16.1_linux-x86_64.tar.xz && \
    tar xvf zephyr-sdk-0.16.1_linux-x86_64.tar.xz && \
    mv zephyr-sdk-0.16.1 /opt/zephyr-sdk && \
    cd /opt/zephyr-sdk && \
    ./setup.sh -t all -h -c && \
    rm /zephyr-sdk-0.16.1_linux-x86_64.tar.xz

#initialize west
RUN west init -m https://github.com/nrfconnect/sdk-nrf --mr v2.4.0 && \
    west update

Then afterwards in the build script, before I do anything, I do 

west update

west zephyr-export

<---- do whatever here, like get code from git or whatever --->

west build

Previously I had these commands before the "west update" command, but they caused my default builder to go to waste, as I needed to use the NCS shell to get anything done. These lines break the builder

# RUN wget https://nsscprodmedia.blob.core.windows.net/prod/software-and-other-downloads/desktop-software/nrf-command-line-tools/sw/versions-10-x-x/10-23-2/nrf-command-line-tools_10.23.2_amd64.deb && \
#  dpkg -i nrf-command-line-tools_10.23.2_amd64.deb && \
#  rm /nrf-command-line-tools_10.23.2_amd64.deb

# RUN dpkg --unpack /opt/nrf-command-line-tools/share/JLink_Linux_V788j_x86_64.deb \
#  && rm -f /var/lib/dpkg/info/jlink.postinst \
#  && dpkg --configure jlink \
#  && apt install -yf \
#  && rm -f /opt/nrf-command-line-tools/share/JLink_Linux_V788j_x86_64.deb

# RUN wget https://developer.nordicsemi.com/.pc-tools/nrfutil/x64-linux/nrfutil -O /usr/local/bin/nrfutil && \
#  chmod +x /usr/local/bin/nrfutil

# RUN nrfutil install toolchain-manager && \
#  nrfutil toolchain-manager install --ncs-version v2.4.0 && \
#  nrfutil toolchain-manager launch --shell && \

I think this issue is related in somewhat to this legacy issue NanoPB and Zephyr SDK toolchain in NCS v2.0.x - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com) - I guess it was never really fixed