Customize your Astro project Dockerfile

By default, the Astro project Dockerfile only includes a FROM statement that specifies your Astro Runtime version. However, you can extend your Dockerfile to use a different distribution or run additional buildtime arguments. Use this document to learn which Dockerfile customizations are supported both locally and on Astro.

Prerequisites

• An Astro project

Use an alternative Astro Runtime distribution

Starting with Astro Runtime 9, each version of Astro Runtime has a separate distribution for each currently supported Python version. Use an alternative Python distribution if any of your dependencies require a Python version other than the default Runtime Python version.

To use a specific Python distribution, update the first line in your Astro project Dockerfile to reference the required distribution:

FROM <registry-url><runtime-version>-python-<python-version>

For example, to use Python 3.10 with Astro Runtime version 9.0.0, you update the first line of your Dockerfile to the following:

FROM <registry-url>9.0.0-python-3.10

Run commands on build

To run additional commands as your Astro project is built into a Docker image, add them to your Dockerfile as RUN commands. These commands run as the last step in the image build process.

For example, if you want to run ls when your image builds, your Dockerfile would look like this:

FROM <registry-url>3.1-5
RUN ls

This is supported both on Astro and in the context of local development.

Add a CA certificate to an Astro Runtime image

If you need your Astro Deployment to communicate securely with a remote service using a certificate signed by an untrusted or internal certificate authority (CA), you need to add the CA certificate to the trust store inside your Astro project’s Docker image.

1. In your Astro project Dockerfile, add the CA certificate to the base Runtime image:

   1
   # Use the base Astro Runtime image so we can setup our CA cert before installing any packages
   2
   FROM <registry-url><runtime-version>-base
   3
   4
   # Switch to root for setup
   5
   USER root
   6
   7
   # Add internal CA certificate
   8
   COPY <internal-ca.crt> /usr/local/share/ca-certificates/<internal-ca.crt>
   9
   RUN update-ca-certificates
   10
   11
   # Install system packages if listed in packages.txt
   12
   COPY packages.txt .
   13
   RUN /usr/local/bin/install-system-packages
   14
   15
   # Install Python dependencies
   16
   COPY requirements.txt .
   17
   RUN /usr/local/bin/install-python-dependencies
   18
   19
   # Switch back to astro user
   20
   USER astro
   21
   22
   # Copy project into image
   23
   COPY --chown=astro:0 . .
   When using a base image, make sure to install the system level and python packages.

2. (Optional) Add additional COPY statements before the RUN update-ca-certificates stanza for each CA certificate your organization is using for external access.

3. Restart your local environment or deploy to Astro. See Deploy code.