How to install python 3.9 on Amazon Linux 2 with cloud-init and CDK

I’m trying to install Python 3.9 an EC2 instance that uses Amazon Linux 2. I tried following this guide: https://computingforgeeks.com/install-latest-python-on-centos-linux/, and I was able to install Python3.9 manually on the EC2 instance by SSH’ing in and running the commands. I’m now trying to setup the EC2 instance with a UserData script that calls some CloudFormationInit scripts to install dependencies, including Python 3.9, and my script is failing.

Here’s part of the script that I’m using to install Python 3.9:

    const installPythonString = `
#!/bin/bash
sudo amazon-linux-extras install -y epel
sudo yum -y update
sudo yum groupinstall "Development Tools" -y
sudo yum install openssl-devel libffi-devel bzip2-devel -y
gcc --version
sudo yum install wget -y
sudo mkdir -p /opt/python3.9/
sudo chown -R $USER:$USER /opt/python3.9/
wget https://www.python.org/ftp/python/3.9.9/Python-3.9.9.tgz -P /opt/python3.9
cd /opt/python3.9/
tar xvf Python-3.9.9.tgz
whoami
sudo chown -R $USER:$USER Python-3.9.9
cd Python-3.9.9/
ls -al
pwd
./configure --enable-optimizations
sudo make altinstall
python3.9 --version
pip3.9 --version
`;
    init.addConfig('install_python39', new ec2.InitConfig([
      ec2.InitFile.fromString('/opt/install_python39.sh', installPythonString, {
        mode: '000755',
        owner: 'root',
        group: 'root',
      }),
      ec2.InitCommand.shellCommand('sudo sh install_python39.sh', {
        cwd: '/opt',
        key: 'install_python39',
      }),
]))

I’m getting the following errors when trying to start up the EC2 instance:

Python build finished successfully!
...
WARNING: The script pip3.9 is installed in '/usr/local/bin' which is not on PATH.
install_python39.sh: line 21: python3.9: command not found
install_python39.sh: line 22: pip3.9: command not found

Is there an easier way to install Python 3.9 on Amazon Linux 2 using CloudFormationInit?

Answer

Looks like the path to the python is /usr/local/bin which is not in $PATH so the python3.9 command is not found.

run the following commands in order.

export PATH="/usr/local/bin:$PATH" or echo "export PATH='/usr/local/bin:$PATH' >> ~/.bashrc(if you do this relaunch the ssh session) to save it to bashrc so you don’t have to run the export everytime you log in.

python3.9 --version

additionally if you keep having issues, follow this to install python3.9, which is what i used, and everything went flawlessly.

if you have python packages that need to be installed, i would recommend creating a requirements.txt and using pip3.9 install -r requirements.txt to install them.