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Composer vs Docker: What are the differences?


This article will discuss the key differences between Composer and Docker, two popular tools used in web development and deployment.

  1. Installation and Purpose: Composer is a dependency management tool specifically designed for PHP projects. It allows developers to easily manage and install the required libraries and packages for their PHP applications. On the other hand, Docker is a platform that enables developers to package their applications into containers along with all the required dependencies and configurations. It provides a way to create consistent and reproducible environments for running applications.

  2. Resource Isolation: Docker provides strong resource isolation capabilities by running applications inside containers. Each container has its own allocated resources and does not share them with other containers or the host system. This allows for better scalability and efficiency, as resources can be easily distributed and managed independently. Composer, on the other hand, does not provide resource isolation as it mainly focuses on dependency management within a PHP project.

  3. Portability and Environment Consistency: Docker containers are portable and can be easily moved between different environments. This ensures that the application will run consistently regardless of the underlying infrastructure. Composer, on the other hand, relies on the local environment and the availability of PHP dependencies on the host system. This can sometimes lead to compatibility and dependency issues when moving the application to a different environment.

  4. Development Workflow: Composer is mainly used during the development phase of a PHP project. It allows developers to easily manage dependencies, add new libraries, and update existing ones. Docker, on the other hand, is used throughout the development and deployment process. It provides a way to create isolated development environments, run tests, and deploy the application to different servers or cloud platforms.

  5. Dependency Management: Composer focuses specifically on managing PHP dependencies, including libraries, frameworks, and plugins. It provides a simple way to specify which versions of dependencies are required and handles the installation and autoloading of these dependencies. Docker, on the other hand, can handle dependencies for different languages and technologies, not just PHP. It allows developers to package all the required dependencies, including system libraries, databases, and other services, into a single container.

  6. Scalability and Load Balancing: Docker provides features for scaling applications by running multiple instances (containers) of the same application and load balancing the traffic between them. This allows for better performance and high availability. Composer, on the other hand, does not have built-in features for scaling or load balancing, as it is primarily focused on dependency management within a single PHP project.

In summary, Composer is a tool for managing PHP dependencies within a project, while Docker is a platform for packaging and running applications in isolated containers with all their dependencies. Docker provides resource isolation, portability, and scalability features, making it suitable for both development and deployment workflows.

Decisions about Composer and Docker
Florian Sager
IT DevOp at Agitos GmbH · | 3 upvotes · 429.1K views

lxd/lxc and Docker aren't congruent so this comparison needs a more detailed look; but in short I can say: the lxd-integrated administration of storage including zfs with its snapshot capabilities as well as the system container (multi-process) approach of lxc vs. the limited single-process container approach of Docker is the main reason I chose lxd over Docker.

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Pros of Composer
Pros of Docker
  • 7
    Must have dependency manager for PHP
  • 3
    Centralized autoload.php
  • 3
    Large number of libraries
  • 823
    Rapid integration and build up
  • 691
  • 521
    Open source
  • 505
    Testa­bil­i­ty and re­pro­ducibil­i­ty
  • 460
  • 218
  • 185
  • 106
    Upgrading / down­grad­ing / ap­pli­ca­tion versions
  • 88
  • 85
    Private paas environments
  • 34
  • 26
    Limit resource usage
  • 17
    Game changer
  • 16
    I love the way docker has changed virtualization
  • 14
  • 12
  • 8
    Docker's Compose tools
  • 6
    Easy setup
  • 6
    Fast and Portable
  • 5
    Because its fun
  • 4
    Makes shipping to production very simple
  • 3
    Highly useful
  • 3
    It's dope
  • 2
    Very easy to setup integrate and build
  • 2
    HIgh Throughput
  • 2
    Package the environment with the application
  • 2
    Does a nice job hogging memory
  • 2
    Open source and highly configurable
  • 2
    Simplicity, isolation, resource effective
  • 2
    MacOS support FAKE
  • 2
    Its cool
  • 2
    Docker hub for the FTW
  • 2
  • 0

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Cons of Composer
Cons of Docker
    Be the first to leave a con
    • 8
      New versions == broken features
    • 6
      Unreliable networking
    • 6
      Documentation not always in sync
    • 4
      Moves quickly
    • 3
      Not Secure

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    - No public GitHub repository available -

    What is Composer?

    It is a tool for dependency management in PHP. It allows you to declare the libraries your project depends on and it will manage (install/update) them for you.

    What is Docker?

    The Docker Platform is the industry-leading container platform for continuous, high-velocity innovation, enabling organizations to seamlessly build and share any application — from legacy to what comes next — and securely run them anywhere

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    Blog Posts

    Jul 9 2019 at 7:22PM

    Blue Medora

    DockerPostgreSQLNew Relic+8
    DockerAmazon EC2Scala+8
    What are some alternatives to Composer and Docker?
    Docker Compose
    With Compose, you define a multi-container application in a single file, then spin your application up in a single command which does everything that needs to be done to get it running.
    Kubernetes is an open source orchestration system for Docker containers. It handles scheduling onto nodes in a compute cluster and actively manages workloads to ensure that their state matches the users declared intentions.
    Docker Swarm
    Swarm serves the standard Docker API, so any tool which already communicates with a Docker daemon can use Swarm to transparently scale to multiple hosts: Dokku, Compose, Krane, Deis, DockerUI, Shipyard, Drone, Jenkins... and, of course, the Docker client itself.
    Create beautiful websites using a simple, intuitive drag and drop Interface.It offers pixel perfect design, yet produces 100% clean code. Take your design vision and turn it into a stunning custom-made website. It's fast and easy.
    Conductor is an orchestration engine that runs in the cloud.
    See all alternatives