Customizing the Dockerfile

When you run fly launch, we create a Dockerfile for you. You may need to customize this for your application!

The Dockerfile we create has three main responsibilities:

  1. Copy the codebase into the container
  2. Configure services (nginx, maybe configure Octane), run composer install and similar
  3. Build static assets (via NodeJS)

The Dockerfile assumes you’ll want to run composer install... and build static assets on deployment.

Customizing Static Assets

If you have static assets already built for production (perhaps committed to Git), you can save a bunch of deployment time by cutting out the step to build static assets.

You can just delete the whole section from the Dockerfile that deals with that - here’s a gist showing the diff.

Installing Extra Stuff

You may also want to install additional stuff!

Here’s an example of installing pecl and pecl-specific modules sqlsrv and pdo_sqlsrv. Don’t tell anyone I said this, but SqlServer is actually a great database, iykyk.

We’ll borrow from Microsoft’s docs here.

The trick here is knowing WHERE in the Dockerfile to install things. Generally, you want extra work to be done BEFORE we COPY our code base into the container. This is because changes to our code base will bust Docker’s build cache, and all the work we do installing stuff will need to be re-done.

If we install things BEFORE the COPY instruction, all that work can get cached and won’t need to be re-done on each deployment!

So, here’s a section of the Dockerfile that shows installing the needed things to get SqlServer working:

# Things above this omitted

LABEL fly_launch_runtime="laravel"


# Note we specify version 18 of SqlServer via package msodbcsql18
RUN curl | apt-key add - \
    && curl > /etc/apt/sources.list.d/mssql-release.list \
    && apt-get update \
    && apt-get install --no-install-recommends -y php${PHP_VERSION}-dev php-pear \
       g++ make msodbcsql18 unixodbc-dev mssql-tools \
    && pecl install sqlsrv \
    && pecl install pdo_sqlsrv \
    && printf "; priority=20\\n" > /etc/php/${PHP_VERSION}/mods-available/sqlsrv.ini \
    && printf "; priority=30\\n" > /etc/php/${PHP_VERSION}/mods-available/pdo_sqlsrv.ini \
    && phpenmod -v ${PHP_VERSION} sqlsrv pdo_sqlsrv

# copy application code, skipping files based on .dockerignore
COPY . /var/www/html

# Things below this omitted

Here’s a diff for full context. We installed a bunch of stuff to get SqlServer drivers installed, and we did it above the line that COPY‘s our code into the container!

Note that we used one RUN command and just ran each command in sequence. This helps reduce the number of instructions in the Dockerfile (and therefore the number of “layers” that make up the Docker image), thus reducing the overall size of the image we deploy onto Fly.

Since we put the installation of our stuff up high above the COPY instruction, this install step should be cached in the Docker builder cache, and shouldn’t normally need to get re-run on every subsequent deployment.