Use a builder stage for Composer dependencies and a lean runtime stage for the application. The examples focus on the implementation and the checks that matter before using it in an application.
What Is the Approach?
Use a builder stage for Composer dependencies and a lean runtime stage for the application.
The following sections use COPY --from and related PHP facilities to demonstrate a small working pattern and the validation needed around it.
Example 1: Basic Usage
This example introduces Creating a Multi-Stage Dockerfile for PHP Applications with a direct call and a small, readable input.
FROM composer:2 AS dependencies
WORKDIR /app
COPY composer.json composer.lock ./
RUN composer install --no-dev --no-interaction --prefer-dist --no-scriptsUse a builder stage for Composer dependencies and a lean runtime stage for the application. Copy vendor dependencies built for the same PHP platform and install matching runtime extensions.
Example 2: Another Behavior or Input
Compare this input with the previous example: changing the data or option can affect how Creating a Multi-Stage Dockerfile for PHP Applications behaves.
FROM php:8.4-cli AS runtime
WORKDIR /app
COPY --from=dependencies /app/vendor /app/vendorThe changed input illustrates why output may differ with the chosen values or environment. Copy vendor dependencies built for the same PHP platform and install matching runtime extensions.
Practical Example: Using the Feature
The following example incorporates Creating a Multi-Stage Dockerfile for PHP Applications into a workflow. Values such as paths, connection handles and configuration options must come from trusted application settings.
FROM composer:2 AS builder
WORKDIR /app
COPY composer.json composer.lock ./
RUN composer install --no-dev --no-interaction --prefer-dist --no-scripts
FROM php:8.4-cli
WORKDIR /app
COPY --from=builder /app/vendor /app/vendor
COPY src/ /app/src/
CMD ["php", "src/app.php"]In a real application, check each operation result, validate values before use and clean up acquired resources. Copy vendor dependencies built for the same PHP platform and install matching runtime extensions.
Important Behavior and Edge Cases
- Purpose: Use a builder stage for Composer dependencies and a lean runtime stage for the application.
- Key limitation: Copy vendor dependencies built for the same PHP platform and install matching runtime extensions.
- Failure handling: Check return values and handle invalid inputs and unavailable operating-system or extension features where relevant.
Comparison With Related Functions
| Function or Approach | Best Fit |
|---|---|
Creating a Multi-Stage Dockerfile for PHP Applications | Use a builder stage for Composer dependencies and a lean runtime stage for the application. |
COPY --from | Copies selected artifacts from an earlier Docker build stage without carrying build-only tools into the final stage. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Copy vendor dependencies built for the same PHP platform and install matching runtime extensions. | The correct approach depends on this behavior: Copy vendor dependencies built for the same PHP platform and install matching runtime extensions. |
| Ignoring errors or cleanup after the operation. | Validate inputs and check each result; close files, restore settings or release resources when the operation requires it. |
Key Takeaways
- Use a builder stage for Composer dependencies and a lean runtime stage for the application.
- Copy vendor dependencies built for the same PHP platform and install matching runtime extensions.
- Use the examples as starting points, and adapt environmental paths, resources and permissions rather than assuming fixed results.
Creating a Multi-Stage Dockerfile for PHP Applications is useful when its specific behavior fits the problem. The safest implementations combine the correct API with input validation, error checking and resource cleanup.