Use Custom Docker Images to Speed Up Tugboat Builds

🚤💨

01 Sep 2020

Tugboat is our tool of choice at Chromatic for building a preview environment for each of our pull requests. For an introduction to Tugboat, see A Testing Environment For Every Pull Request.

Out of the Box #

One of Tugboat’s most compelling features is that it is fast, but that hasn’t stopped us from pursuing making it even faster. We wanted to turn our tugboat into a speedboat.

The Tugboat-provided Docker images do a great job of providing most of what you will need, but it is common for us to install a few additional tools during Tugboat’s init step so that they’re available for our builds. For example, we install awscli to download database dumps, yarn to build our front-end assets, and redis-tools so we can talk to our cache service.

commands:
  init:
    - apt-get update
    - apt-get install --yes google-chrome-stable python3-pip redis-tools software-properties-common yarn
    - pip3 install ansible awscli

Custom Docker Images #

When using Tugboat’s base preview functionality, the speed at which these tools install is only a minor concern as it does not happen on every build, but if you are frequently building previews from scratch, there is an opportunity for improvement by building a custom Docker image. We took all of the tools that we were installing in our init step and created a custom Docker image with them already installed. Since our image is based on an official tugboatqa image, we get to retain all of the features that they have already built-in.

ARG PHP_VERSION
FROM tugboatqa/php:${PHP_VERSION}-apache
ENV COMPOSER_DISCARD_CHANGES=true
ENV COMPOSER_NO_INTERACTION=true
ENV COMPOSER_ALLOW_SUPERUSER=true
RUN curl -sL https://deb.nodesource.com/setup_10.x | bash - \
    && curl -sL https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add - \
    && echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list \
    && wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add - \
    && echo "deb http://dl.google.com/linux/chrome/deb/ stable main" > /etc/apt/sources.list.d/google.list \
    && apt-get update \
    && apt-get --quiet install -y --no-install-recommends \
      google-chrome-stable \
      nodejs \
      python3-pip \
      redis-tools \
      software-properties-common \
      yarn \
    && pip3 install --upgrade setuptools \
    && pip3 install ansible awscli \
    && yes '' | pecl install -fo redis \
    && rm -rf /tmp/pear \
    && docker-php-ext-install opcache \
    && docker-php-ext-enable opcache \
    && docker-php-ext-enable redis \
    && a2enmod headers rewrite \
    && apt-get clean \
    && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

Now, when our Tugboat environment builds, it pulls this custom image and can move right on past the init stage because we have pre-packaged everything within the image. Your build-time savings will vary based on how much you are currently installing in the init step, but in the example above, we improved our build speed by approximately 5 minutes when building previews from scratch. 🚤💨

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