Deploying applications in an isolated network environment requires preparing all necessary assets on a connected machine before transferring them. This guide outlines the procedure for setting up a Python 3.9 environment and project dependencies on an offline CentOS server.

Phase 1: Resource Preparation (Online Machine)

Begin by preparing a directory structure to store the downloaded system libraries and Python packages.

mkdir -p /opt/pkg_downloads/rpm_deps
mkdir -p /opt/pkg_downloads/python_wheels

Install the utility required to download RPM packages without installing them immediately.

yum install yum-utils -y

Download the necessary compiler and development libraries required for building Python. These dependencies handle compression, encryption, and database support.

yumdownloader --resolve --destdir=/opt/pkg_downloads/rpm_deps \
gcc make \
zlib-devel bzip2-devel \
openssl-devel ncurses-devel \
sqlite-devel readline-devel \
tk-devel libffi-devel

Obtain the Python source code archive from the official repository. For this example, version 3.9.0 is utilized. Extract the archive and compile the binaries.

# Navigate to the source directory
cd /opt/pkg_downloads

# Extract the archive
tar -xvf Python-3.9.0.tgz
cd Python-3.9.0

# Configure installation path and optimize builds
./configure --prefix=/opt/python-3.9 --enable-optimizations

# Compile and install
make && make install

Create symbolic links to ensure the Python binaries are accessible system-wide.

ln -sf /opt/python-3.9/bin/python3.9 /usr/bin/python3
ln -sf /opt/python-3.9/bin/pip3.9 /usr/bin/pip3

Generate a requirements file for your project if one does not exist, then download all project dependencies as wheel files. Wheel files are preferred for offline installation as they are pre-compiled.

# Download dependencies to the local directory
pip3 download -r requirements.txt -d /opt/pkg_downloads/python_wheels

Phase 2: Environment Setup (Offline Machine)

Transfer the directory /opt/pkg_downloads from the online machine to the offline server using portable storage.

Install the system dependencies using the RPM files collected earlier. The --nodeps and --force flags are used to bypass potential circular dependency checks during the bulk install, as the resolver cannot access remote repositories.

cd /opt/pkg_downloads/rpm_deps
rpm -Uvh *.rpm --nodeps --force

Proceed with the compilation and installation of Python on the offline server using the source code.

cd /opt/pkg_downloads
tar -xvf Python-3.9.0.tgz
cd Python-3.9.0

./configure --prefix=/opt/python-3.9 --enable-optimizations
make && make install

ln -sf /opt/python-3.9/bin/python3.9 /usr/bin/python3
ln -sf /opt/python-3.9/bin/pip3.9 /usr/bin/pip3

Verify the Python installation.

python3 --version

Install the Python project dependencies from the local wheel repository without accessing the internet.

pip3 install --no-index --find-links=/opt/pkg_downloads/python_wheels -r requirements.txt

Application Execution

Navigate to the project directory and launch the application.

cd /path/to/project
python3 main.py