php composer

    Why should always run ‘composer install’ in production?

    In the fast-changing world of web development, where apps always change to fit new needs, controlling what your app relies on is super important to keep it stable and reliable. Composer is a popular tool for PHP developers to handle these dependencies well. But there’s one command, composer update that can cause issues if used in a live environment. This article looks into why it’s risky to run composer update in production and suggests safer ways to handle your app’s dependencies without risking its stability.

    Understanding Composer: The PHP Dependency Manager

    Before we dive into why you should use composer install in production, it’s essential to understand what Composer is and its role in PHP development. Composer is a dependency manager for PHP, offering a streamlined solution to handle libraries and packages within a project. It simplifies the process of managing external dependencies, allowing developers to define and install the libraries their project relies on.

    Composer operates based on a composer.json file, where developers specify the required dependencies and their versions. The accompanying composer.lock file records the exact versions of these dependencies installed in the project. When composer install is executed, Composer reads these files and installs the specified versions, ensuring consistency across different environments.

    The true power of Composer lies in its ability to resolve and manage dependencies recursively. It not only installs the direct dependencies but also handles the dependencies of those dependencies. This recursive approach ensures that the entire project ecosystem is in sync, with compatible versions of libraries working harmoniously.

    While Composer is an invaluable tool for managing dependencies during development, caution arises when considering its usage in production. The delicate balance between keeping dependencies up-to-date and maintaining the stability of a live application is a crucial aspect of effective software development and deployment.

    Understanding composer install vs. composer update

    To comprehend the apprehension around composer update, it’s crucial to distinguish between composer install and composer update. While composer install installs dependencies based on the exact versions specified in the composer.lock file, composer update goes a step further by updating all dependencies and generating a new composer.lock file. This key distinction sets the stage for potential issues when updating dependencies in a live production environment.

    The Locking Mechanism

    The composer.lock file serves as a snapshot of the exact versions of dependencies that your application is using. When you run composer install, it installs the versions specified in this lock file, ensuring consistency across different environments. On the other hand, composer update discards the existing lock file, potentially introducing newer versions of dependencies, which might lead to compatibility issues.

    The Fear of Breakage

    The fear associated with running composer update in production stems from the unpredictability introduced by updating dependencies. Even with tight version constraints your composer.json, the recursive nature of Composer may lead to updates in your dependencies’ dependencies. While most updates won’t cause problems, there’s a risk that a behavior change introduced several layers down the dependency chain, could impact your code in unanticipated ways.

    Real-World Scenarios

    Consider a situation where a critical extension, such as the pcntl module, requires an update. The temptation to run composer update to address this issue might arise. However, doing so in a production environment could lead to unforeseen conflicts and breakages, especially if the update introduces changes that haven’t been thoroughly tested against your application.

    Best Practices: Always Run Install in Production

    Given the potential risks, experienced developers often advise against running composer update directly in a production environment. Instead, a more structured approach is recommended:

    1. Perform Updates Elsewhere: Execute composer update in a development environment or a dedicated staging server. This allows you to assess the impact of updates without risking the stability of your live application.
    2. Separate Environments: Create a separate copy of your application, ensuring that the updating process does not interfere with the live application being served to users.
    3. Deploy a Fresh Installation: If updates are necessary, opt for composer install to create a fresh installation based on the existing composer.lock file. This approach provides more predictability and reliability compared to the potentially unpredictable nature of composer update.
    4. Optimize and Test: Before deploying to production, optimize your autoloader, run after-install scripts, and thoroughly test the new version in a staging environment. This step ensures that any potential issues are identified and addressed before reaching the live environment.
    5. Use Deployment Tools: Composer is primarily a dependency management tool, not a deployment tool. Consider utilizing dedicated deployment tools to push your code to production. This could involve code deployment tools or even simple scripts for tasks like FTP uploads.
    6. Symlink for Swift Updates: To minimize downtime and avoid impacting a running application, consider using a symlink as the “production” root. This allows for quick updates by replacing the symlink with the new release once the deployment is ready.


    In conclusion, the caution surrounding composer update in production is rooted in the potential risks associated with dependency changes. By adhering to best practices, such as updating dependencies in a controlled environment, thoroughly testing updates, and deploying with precision, developers can strike a balance between keeping their applications up-to-date and ensuring the stability of live production systems. Remember, the key is to approach dependency management with care and strategic planning to mitigate the risks inherent in dynamic software ecosystems.