Stay organized with collections
Save and categorize content based on your preferences.
An App Engine app is configured using an app.yaml
file, that contains CPU, memory, network and disk resources, scaling, and other
general settings including environment variables.
About app.yaml files
You can specify the runtime configuration for your Custom Runtime app,
including versions and URLs, in the app.yaml file. This file acts as a
deployment descriptor of a specific service version.
You must first create the app.yaml file for the default service of your app
before you can create and deploy app.yaml files for additional services.
runtime:customenv:flex
Depending on the complexity of your app's service, you might only need to define
a few elements in the corresponding app.yaml file. The following example
demonstrates what a simple Custom Runtime app might require in the
flexible environment:
You can specify a unique name for your app.yaml files, but then you must
specify the file name with the deployment
command
as well. For example, if you name your app.yaml file service-name-app.yaml
or app.flexible.yaml, then you must deploy your app using either:
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-29 UTC."],[[["\u003cp\u003eThe \u003ccode\u003eapp.yaml\u003c/code\u003e file configures an App Engine app, defining resources like CPU, memory, network, disk, scaling, environment variables, and general settings.\u003c/p\u003e\n"],["\u003cp\u003eIt serves as a deployment descriptor, defining runtime configurations, versions, and URLs for a specific service version within your app.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eapp.yaml\u003c/code\u003e file for the \u003ccode\u003edefault\u003c/code\u003e service must be created first before other \u003ccode\u003eapp.yaml\u003c/code\u003e files for additional services.\u003c/p\u003e\n"],["\u003cp\u003eYou can use a unique name for \u003ccode\u003eapp.yaml\u003c/code\u003e files, but you must specify this file name in the deployment command, such as \u003ccode\u003egcloud app deploy service-name-app.yaml\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe flexible environment allows for custom runtime configuration in the \u003ccode\u003eapp.yaml\u003c/code\u003e file, and its complexity determines how many elements you need to specify.\u003c/p\u003e\n"]]],[],null,["# Configuring your app with app.yaml\n\n\u003cbr /\u003e\n\n\u003cbr /\u003e\n\n\u003cbr /\u003e\n\n\u003cbr /\u003e\n\n\u003cbr /\u003e\n\n\u003cbr /\u003e\n\n\nAn App Engine app is configured using an `app.yaml`\nfile, that contains CPU, memory, network and disk resources, scaling, and other\ngeneral settings including environment variables.\n\n\nAbout `app.yaml` files\n----------------------\n\n\u003cbr /\u003e\n\nYou can specify the runtime configuration for your Custom Runtime app, including versions and URLs, in the `app.yaml` file. This file acts as a deployment descriptor of a specific service version. You must first create the `app.yaml` file for the `default` service of your app before you can create and deploy `app.yaml` files for additional services.\n\n\n runtime: custom\n env: flex\n\nDepending on the complexity of your app's service, you might only need to define a few elements in the corresponding `app.yaml` file. The following example demonstrates what a simple Custom Runtime app might require in the flexible environment:\n\nYou can specify a unique name for your `app.yaml` files, but then you must\nspecify the file name with the [deployment\ncommand](/appengine/docs/flexible/testing-and-deploying-your-app)\nas well. For example, if you name your `app.yaml` file `service-name-app.yaml`\nor `app.flexible.yaml`, then you must deploy your app using either: \n\n gcloud app deploy service-name-app.yaml\n gcloud app deploy app.flexible.yaml\n\n\u003cbr /\u003e\n\nAll configuration elements\n--------------------------\n\nFor a complete list of all the supported elements in this configuration file,\nsee the\n[`app.yaml` reference](/appengine/docs/flexible/reference/app-yaml)."]]
