Example: Install tools

Application images are designed to be as lightweight as possible, and as such, common tools you might expect to see in a regular cloud image might not be available.

You can use hooks to install packages that you require for your application. In this example, we’ll install curl and python3.

To do so, create a new addon with the following pre-start hook:

#!/bin/bash -e

# We only need to install things once when the image is being created, so we
# don't need to execute the hook when users are running the application.
if  [ "$CONTAINER_TYPE" = "regular" ]; then
  exit 0
fi

apt update -q
apt install -y curl python3

When an application is created or updated with this addon, both curl and python3 will be installed and made available for other hooks to use.