Building of a Docker image with Qt5 compiled with MinGW works in a container run from "docker:latest" image, but fails in GitLab CI

I want to prepare a docker image with Qt5 with MinGW. Part of the process is building Qt 5.14.0 with MinGW and that is the part where it fails.

Building on my machine.

There weren't any problems when I pulled the docker:latest image on my PC, ran container from it and built my image in this container. It worked fine.

Building in GitLab CI pipeline.

When I pushed the Dockerfile in Gitlab, where it is built in container from the same docker:latest image, it fails to build Qt with the following error message:

Could not find qmake spec ''.

Error processing project file: /root/src/qt-everywhere-src-5.14.0

Screenshot of the failure

CI script:

stages:
  - deploy

variables:
  CONTAINER_NAME: "qt5-mingw"
  PORT: "5000"

image: docker:latest

build-snapshot:
  stage: deploy
  tags:
    - docker
    - colo
  environment:
    name: snapshot
    url: https://somedomain.com/artifactory/#/artifacts/qt5-mingw
  before_script:
    - docker login -u ${ARTIFACT_USER} -p ${ARTIFACT_PASS} somedomain.com:${PORT}
  script:
    - docker build -f Dockerfile -t ${CONTAINER_NAME} .
    - export target_version=$(docker inspect --format='{{index .Config.Labels "com.domain.version" }}' ${CONTAINER_NAME})
    - docker tag ${CONTAINER_NAME} dsl.domain.com:${PORT}/${CONTAINER_NAME}:${target_version}
    - docker tag dsl.domain.com:${PORT}/${CONTAINER_NAME}:${target_version} dsl.domain.com:${PORT}/${CONTAINER_NAME}:latest
    - docker push dsl.domain.com:${PORT}/${CONTAINER_NAME}:${target_version}
    - docker push dsl.domain.com:${PORT}/${CONTAINER_NAME}:latest
  after_script:
    - docker logout dsl.domain.com:${PORT}
    - docker rmi ${CONTAINER_NAME}
  except:
    - master
    - tags

The Dockerfile:

FROM debian:buster-slim

########################
# Install what we need
########################

# Custom Directory
ENV CUSTOM_DIRECTORY YES
ENV WDEVBUILD /temp/build
ENV WDEVSOURCE /temp/src
ENV WDEVPREFIX /opt/windev

# Custom Version
ENV CUSTOM_VERSION NO
ENV QT_SERIES 5.14
ENV QT_BUILD 0
ENV LIBJPEGTURBO_VERSION 2.0.3
ENV LIBRESSL_VERSION 3.0.2
ENV OPENSSL_VERSION 1.1.1c
ENV UPX_VERSION 3.95

# SSL Choice
ENV USE_OPENSSL YES

# Exclude Static Qt
ENV BUILD_QT32_STATIC NO
ENV BUILD_QT64_STATIC NO

# Copy directory with qt_build script
COPY rootfs /

# install tools
RUN apt-get update \
  && apt-get install -y bash \
        cmake \
        coreutils \
        g++ \
        git \
        gzip \
        libucl1 \
        libucl-dev \
        make \
        nasm \
        ninja-build \
        perl \
        python \
        qtchooser \
        tar \
        wget \
        xz-utils \
        zlib1g \
        zlib1g-dev \
  && apt-get install -y binutils-mingw-w64-x86-64 \
        mingw-w64-x86-64-dev \
        g++-mingw-w64-x86-64 \
        gcc-mingw-w64-x86-64 \
        binutils-mingw-w64-i686 \
        mingw-w64-i686-dev \
        g++-mingw-w64-i686 \
        gcc-mingw-w64-i686 \
  && rm -rf /temp \
    && rm -rf /var/lib/apt/lists/*

# Build Qt with mingw and the step where it fails.
RUN /opt/windev/bin/qt_build \



LABEL com.domain.version="1.0.0"
LABEL vendor="Someone"
LABEL com.domain.release-date="2020-01-21"

Debugging process so far:

The version of the docker:latest is the same in both cases.
The version of MinGW is the same in both cases.
I tried also with Qt 5.12.6 and the result is the same.

Solution

I have found it. I think the answer is here.

The package libseccomp2 is 2.3.1 on the CI Runner machine and 2.4.1 on my PC. But Qt versions after 5.10 are using system call that has been added in 2.3.3, so that's why it can be build on my PC and can't be built on the runner.

Reamrak: It doesn't matter that it is build in container run from docker:latest image, because the Docker Daemon is mounted when the container is started, so apparently it continue to use some features of the host and the docker work is not completely containerized.