This page covers instructions for migrating from the first-generation to the second-generation PHP runtimes. To upgrade your second-generation app to use the latest supported version of PHP, see Upgrade an existing application.
PHP 5 has reached end of support on January 30, 2024. Your existing PHP 5 applications will continue to run and receive traffic. However, App Engine might block re-deployment of applications that use runtimes after their end of support date. We recommend that you migrate to the latest supported runtime PHP runtime by using the guidelines in this page.
Migrating to a supported second-generation PHP runtime lets you use up-to-date language features and build apps that are more portable, with idiomatic code.
Compatibility issues between PHP 5.5 and the second-generation PHP runtimes
The official PHP documentation provides information on migrating from different PHP versions:
- Migrating from PHP 5.5.x to PHP 5.6.x
- Migrating from PHP 5.6.x to PHP 7.0.x
- Migrating from PHP 7.0.x to PHP 7.1.x
- Migrating from PHP 7.1.x to PHP 7.2.x
- Migrating from PHP 7.2.x to PHP 7.3.x
- Migrating from PHP 7.3.x to PHP 7.4.x
- Migrating from PHP 7.4.x to PHP 8.0.x
- Migrating from PHP 8.0.x to PHP 8.1.x
Key differences between PHP 5.5 and the second-generation PHP runtimes
The following is a summary of the differences between the PHP 5.5 and the second-generation PHP runtimes in the App Engine standard environment:
Memory usage differences
Second-generation runtimes see a higher baseline of memory usage compared to first-generation runtimes. This is due to multiple factors, such as different base image versions, and differences in how the two generations calculate memory usage.
Second-generation runtimes calculate instance memory usage as the sum of what an application process uses, and the number of application files dynamically cached in memory. To avoid memory-intensive applications from experiencing instance shutdowns due to exceeding memory limits, upgrade to a larger instance class with more memory.
CPU usage differences
Second-generation runtimes can see a higher baseline of CPU usage upon instance cold-start. Depending on an application's scaling configuration, this might have unintended side effects, such as, a higher instance count than anticipated if an application is configured to scale based on CPU utilization. To avoid this issue, review and test application scaling configurations to ensure the number of instances are acceptable.
Request header differences
First-generation runtimes allow request headers with underscores
(e.g. X-Test-Foo_bar
) to be forwarded to the application. Second-generation
runtimes introduces Nginx into the host architecture. As a result of this
change, second-generation runtimes are configured to automatically remove
headers with underscores (_
). To prevent application issues, avoid using
underscores in application request headers.
Migrating your app.yaml
file
You must place a front controller to handle all routing in your application. For more information, see Application startup.
The second-generation PHP runtimes don't allow the script
handler element to be
customized. The only valid value is auto
, because all traffic is served using
the entrypoint command. All non-static URL handlers must include script: auto
to deploy successfully.
The behavior of some elements in the app.yaml
configuration file has been
modified:
Element | Change type | Description |
---|---|---|
entrypoint | Added | Optionally, use this field to specify the command that will run when your app starts. |
threadsafe | Deprecated | All applications are presumed to be threadsafe, meaning an instance can handle multiple requests at the same time. |
api_version | Deprecated | Previously required but not needed in the second-generation PHP runtimes. |
application_readable | Deprecated | |
builtins | Deprecated | |
libraries | Deprecated | Arbitrary third
party dependencies can be installed using a composer.json
metadata file. |
handlers | Modified |
|
If you use of any of the deprecated fields, there will be an error on app deployment.
For more information, see the app.yaml
reference.
Reduced runtime restrictions
The second-generation PHP runtimes have fewer restrictions compared to the PHP 5.5 runtime.
- Install third-party dependencies.
- The runtime includes a full filesystem.
- Create background threads or processes that live beyond the scope of the request while the instance runs.
- Use the Google Cloud Client Library for PHP to integrate apps with other Google Cloud services. For more information, see the Installing the Google Cloud Client Library page.
For more information, see the PHP runtime environment.
Migrate from the App Engine PHP SDK
To reduce runtime migration effort and complexity, the App Engine standard environment lets you access many of legacy bundled services and APIs in the second-generation PHP runtime, such as Memcache. Your second-generation PHP app can call the bundled services APIs through the App Engine SDK, and access most of the same capabilities as on the PHP 5 runtime. Not all the legacy bundled services available for PHP 5 have a corresponding service in the second-generation PHP runtimes. For the full list of legacy bundled services APIs available for the second-generation PHP runtimes, see the legacy bundled services API references documentation.
You also have the option to use Google Cloud products that offer similar capabilities as the legacy bundled services. These Google Cloud products provide idiomatic Google Cloud CLI client library. For the legacy bundled services that are not available as separate products in Google Cloud, such as search, you can use third-party providers or other workarounds. To learn more about migrating to unbundled services, see Migrating from bundled services.
Running your application locally
To test your application and run it locally:
Locally install a version of PHP that corresponds to a second-generation PHP runtime available in the App Engine standard environment.
Install a web server and use this to serve your app locally.
For example, start the HTTP server by running the following command:
php -S localhost:8080
Then, view your application in your web browser at http://localhost:8080.