@expo/fingerprint v0.10.3
@expo/fingerprint
A library to generate a fingerprint from a React Native project
Table of Contents
API Usage
import * as Fingerprint from '@expo/fingerprint';
await Fingerprint.createFingerprintAsync('/projectRoot');
createFingerprintAsync
Create a fingerprint from project
function createFingerprintAsync(projectRoot: string, options?: Options): Promise<Fingerprint>;
Example:
const fingerprint = await createFingerprintAsync('/app');
console.log(fingerprint);
{
"sources": [
{
"type": "file",
"filePath": "app.json",
"reasons": ["expoConfig"],
"hash": "378083de0c6e6bb6caf8fb72df658b0b26fb29ef"
},
{
"type": "file",
"filePath": "eas.json",
"reasons": ["easBuild"],
"hash": "f723802b6ea916d1a6c4767b2299cc81ddb22eb4"
},
{
"type": "dir",
"filePath": "node_modules/expo",
"reasons": ["expoAutolinkingIos", "expoAutolinkingAndroid", "bareRncliAutolinking"],
"hash": "1faee4057fa943300905750b51c3b0cbf05f4b0d"
}
],
"hash": "bf8a3b08935f056270b1688333b02f1ef5fa25bf"
}
createProjectHashAsync
Create a native hash value from project
function createProjectHashAsync(projectRoot: string, options?: Options): Promise<string>;
Example:
const hash = await createProjectHashAsync('/app');
console.log(hash);
bf8a3b08935f056270b1688333b02f1ef5fa25bf
diffFingerprintChangesAsync
Diff the given fingerprint
with the current project fingerprint state
function diffFingerprintChangesAsync(fingerprint: Fingerprint, projectRoot: string, options?: Options): Promise<FingerprintSource[]>;
Example:
const fingerprint = {
sources: [
{
type: 'file',
filePath: 'app.json',
reasons: ['expoConfig'],
hash: '378083de0c6e6bb6caf8fb72df658b0b26fb29ef',
},
{
type: 'file',
filePath: 'eas.json',
reasons: ['easBuild'],
hash: 'f723802b6ea916d1a6c4767b2299cc81ddb22eb4',
},
{
type: 'dir',
filePath: 'node_modules/expo',
reasons: ['expoAutolinkingIos', 'expoAutolinkingAndroid', 'bareRncliAutolinking'],
hash: '1faee4057fa943300905750b51c3b0cbf05f4b0d',
},
],
hash: 'bf8a3b08935f056270b1688333b02f1ef5fa25bf',
};
const result = await diffFingerprintChangesAsync(fingerprint, '/app');
console.log(result);
[
{
"filePath": "ios",
"hash": "e4190c0af9142fe4add4842777d9aec713213cd4",
"reasons": ["bareNativeDir"],
"type": "dir"
},
{
"filePath": "app.json",
"hash": "9ff1b51ca9b9435e8b849bcc82e3900d70f0feee",
"reasons": ["expoConfig"],
"type": "file"
}
]
diffFingerprints
Find the diff between two fingerprints
function diffFingerprints(fingerprint1: Fingerprint, fingerprint2: Fingerprint): FingerprintSource[];
CLI Usage
Generate a fingerprint for a given project
npx @expo/fingerprint /path/to/projectRoot
Generate a fingerprint for a given project and write it to a file
npx @expo/fingerprint /path/to/projectRoot > fingerprint.json
Compare a fingerprint with the current project state
npx @expo/fingerprint /path/to/projectRoot fingerprint.json
Customizations
Include or exclude extra files in the .fingerprintignore file
Our default ignore paths, found here DEFAULT_IGNORE_PATHS
, make hashing fast and keep hashing results stable. If the default setup does not fit your workflow, you can add a .fingerprintignore file in your project root. It works like .gitignore but with some slight differences: We use minimatch
for pattern matching with the limitations.
Here's how to use .fingerprintignore: To skip a whole folder but keep some files, you can do this:
# Ignore the entire /app/ios folder
/app/ios/**/*
# But still keep /app/ios/Podfile and /app/ios/Podfile.lock
!/app/ios/Podfile
!/app/ios/Podfile.lock
Limitations
Limited support for config-plugins raw functions
When using config-plugins with raw functions, it's essential to be aware of certain limitations, particularly in the context of fingerprinting. Expo makes its best effort to generate fingerprints for changes made through config-plugins; however, raw functions pose specific challenges. Raw functions are not serializable as fingerprints, which means they cannot be directly used for generating unique hashes.
To work around this limitation, Expo employs one of the following strategies to create serializable fingerprints for raw functions:
Using
Function.name
: Expo utilizes theFunction.name
property if available for named raw functions. This property provides a recognizable name for the function, which can be used as a fingerprint property.Using
withAnonymous
: For anonymous raw functions without aFunction.name
, Expo resorts to using 'withAnonymous' as the fingerprint property. This is a generic identifier for anonymous functions.
Here's an example to illustrate these concepts:
// In app.config.js
const { withInfoPlist } = require('expo/config-plugins');
const withMyPlugin = (config) => {
return withInfoPlist(config, (config) => {
config.modResults.NSLocationWhenInUseUsageDescription = 'Allow $(PRODUCT_NAME) to use your location';
return config;
});
};
export default ({ config }) => {
config.plugins ||= [];
config.plugins.push(withMyPlugin);
config.plugins.push((config) => config);
return config;
};`
In this example, Expo will use 'withMyPlugin', 'withAnonymous' as plugin properties for fingerprint hashing.
It's important to note that due to this design, if you make changes to the implementation of raw config-plugins functions, such as altering the Info.plist value within 'withMyPlugin', the fingerprint will still generate the same hash value. To ensure unique fingerprints when modifying config-plugins implementations, consider the following options:
Avoid Anonymous Functions: Avoid using anonymous raw config-plugins functions. Instead, use named functions whenever possible, and ensure that their names remain consistent as long as the implementation changes.
Use Local config-plugins: Alternatively, you can create local config-plugins as separate modules, each with its own export. This approach allows you to specify a different function name when making changes to the config-plugins implementations.
Here's an example of using a local config-plugin:
// In ./plugins/withMyPlugin.js const { withInfoPlist } = require('expo/config-plugins'); const withMyPlugin = (config) => { return withInfoPlist(config, (config) => { config.modResults.NSLocationWhenInUseUsageDescription = 'Allow $(PRODUCT_NAME) to use your location'; return config; }); }; module.exports = withMyPlugin;
// in app.json { "expo": { // ... "plugins": "./plugins/withMyPlugin" } }
By following these guidelines, you can effectively manage changes to config-plugins and ensure that fingerprinting remains consistent and reliable.
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