5 dep check

Tommy Nguyen редактировал(а) эту страницу 2021-05-31 08:56:25 +02:00

Содержание

• Design: @rnx-kit/dep-check
• Terminology
• Motivation
• 1. Which packages should I use?
• 2. How do I align all of my code on the same set of packages and versions?
• 3. How do I align all apps on the same set of packages and versions?
• Design
• Capabilities
• Profiles
• Putting it all together
• Zero-config
• Extensions
• Alternatives

A copy of this document is also included in @rnx-kit/dep-check/README.md.

Design: @rnx-kit/dep-check

dep-check is a dependency manager and linter that aims to bring alignment to all React Native developers who are working in any-size repositories, from small self-contained repositories to big, enterprise monorepos.

Terminology

• experience — As opposed to apps that get shipped in e.g. App Store or Play Store, experiences may be a single screen (or multiple) integrated into an app. They are normally not shipped as standalone apps.
• monorepo — A single repository in which many projects live. These can range from single-purpose libraries to experiences or full-fledged apps. For instance, https://github.com/microsoft/rnx-kit is a monorepo containing many useful tools, including dep-check.

Motivation

The design of dep-check is driven mainly by the following questions:

1. Which packages should I use?

There is currently no centralised place where developers can go to and get a list of recommended modules, and which versions they should be using when targeting a specific version of React Native. How do you know whether a module is still maintained? Are the maintainers still around to review PRs? Is the module being used by others?

Take AsyncStorage as an example. This is a module that used to ship with React Native. It then got moved out to the React Native Community organization as @react-native-community/async-storage as part of the Lean Core effort. It later got ejected from React Native Community, and was renamed @react-native-async-storage/async-storage. If you don't know the full story of what happened here, there is little chance you know that AsyncStorage from core, @react-native-community/async-storage, and @react-native-async-storage/async-storage are all the same module. Or that @react-native-community/netinfo was a fork of react-native-netinfo that later became the "official" one.

2. How do I align all of my code on the same set of packages and versions?

Ideally, all apps are always on the latest version of react-native and are using a common set of well maintained community modules. Unfortunately, the reality is that some apps are on a two year old version of react-native and some modules that are no longer maintained, while others are on a somewhat recent version of react-native but on an older version of WebView than what others use. When you're responsible for an experience that goes into many apps, you may be forced to provide support for both scenarios (and others), and that's where most feel the pain. How can you make sure that your experiences' dependencies play well with each other or even other experiences? The pain is magnified in a monorepo with many developers as breakages can come from a single package being out of sync with the others. Breakages caused by such packages are hard to debug and pinpoint the cause. In a monorepo, it is very important to ensure that all packages are on the same versions.

3. How do I align all apps on the same set of packages and versions?

When integrating multiple experiences into an existing app, it can sometimes be difficult to determine the dependencies that need to be installed. For example, given two experiences with dependencies as below:

{
  "name": "experience-A",
  "version": "1.0.0",
  "peerDependencies": {
    "react-native": "^0.63 || ^0.64",
    "react-native-netinfo": "^5.7.1 || ^6.0.0"
  }
}

{
  "name": "experience-B",
  "version": "1.0.0",
  "peerDependencies": {
    "react-native": "^0.63",
    "react-native-netinfo": "^5.7.1 || ^6.0.0"
  }
}

In this example, it's not so hard to see that the integrating app should be using react-native 0.63 and react-native-netinfo 6.0.0. However, imagine that there are multiple experiences and many more dependencies. It's not hard to see that it can quickly become very messy to go through all of them and make sure that the app's package.json satisfies all of them, and without causing any conflicts. And you'll have to do this every time one or more packages get updated. Not all experiences will be declaring their dependencies correctly, e.g. putting react-native-netinfo under dependencies and causing multiple versions of react-native-netinfo to be bundled. When it is time to update React Native to the latest version, can you do that and still be confident that all your modules will still work?

Design

dep-check attempts to solve these issues by aligning users on a centralised repository of dependencies. Initially, the repository will be seeded with popular packages, but the goal for it is to become crowd-sourced so that we all can benefit from the latest fixes and features without all having to be up-to-date on everything that goes within the React Native community.

Capabilities

Modules usually provide one or more features. For instance, @react-native-async-storage/async-storage provides a simple key-value storage, react-native-webview provides a web view component, and so on. Knowing which modules are providing the desired features can be tricky. With dep-check, we propose the use of generic names, or capabilities as we call them, that map directly to a package:

Capability	Description	Package
netinfo	Device network information	@react-native-community/netinfo
storage	Key-value storage	@react-native-async-storage/async-storage
webview	WebView component	react-native-webview

dep-check also defines a set of core capabilities. These are capabilities that provide platform support, and are currently defined in the below table:

Capability	Platform	Package
core-android	Android	react-native
core-ios	iOS	react-native
core-macos	macOS	react-native-macos
core-windows	Windows	react-native-windows

With generic names, we are more resilient against module renames since we can recommend the old name in one version, and the new name in the next. We could even provide a fork with security fixes or backwards compatibility shims for long term support. We will see how this can be achieved with profiles in the next section.

Profiles

We cannot force everyone to be on the latest version of react-native. Sometimes it's not desirable, e.g. due to bugs, or feasible due to constraints or lack of expertise. What we can do, however, is to try lessen the pain of supporting multiple versions of react-native and community modules. To that end, dep-check introduces the concept of profiles. A profile is a single set of all capability to package@version mappings, usually tied to a single version of react-native. For instance, the following table is a partial profile for react-native 0.63 (full listing here):

Capability	Package
core-android	react-native@^0.63.2
core-ios	react-native@^0.63.2
core-macos	react-native-macos@^0.63.0
core-windows	react-native-windows@^0.63.0
netinfo	@react-native-community/netinfo@^5.7.1
react	react@16.13.1
storage	@react-native-community/async-storage@^1.12.1
webview	react-native-webview@^11.4.2

Here's the partial profile for react-native 0.64 (full listing here):

Capability	Package
core-android	react-native@^0.64.2
core-ios	react-native@^0.64.2
core-macos	react-native-macos@^0.64.0
core-windows	react-native-windows@^0.64.0
netinfo	@react-native-community/netinfo@^6.0.0
react	react@17.0.1
storage	@react-native-async-storage/async-storage@^1.15.3
webview	react-native-webview@^11.4.2

A package declares what capabilities it requires, which versions of react-native it supports, and dep-check will populate the package's package.json with the modules and versions that it should use. For instance, if a package that supports react-native 0.63 requires core-ios, netinfo, and react, dep-check will add react-native@^0.63.2, @react-native-community/netinfo@^5.7.1, and react@16.13.1.

When the package is migrated from one profile version to the next, the author should be prompted to bump a few packages. For instance, besides bumping react-native, they also should bump react to 17.0.1, and @react-native-community/netinfo to ^6.0.0. We also note that @react-native-community/async-storage was renamed to @react-native-async-storage/async-storage. While users are on older profiles, they should be warned of upcoming, potentially breaking changes such as this so they can be prepared.

Besides package renames, we can also recommend alternative modules that provide the same capability, or forks that include security fixes or shims for backwards compatibility where long term support is a concern.

Putting it all together

Now that we know the basic concepts, let's take a look at how it works. We'll start with configuring the examples from earlier. experience-A depends on react-native and react-native-netinfo. According to our list of capabilities, they correspond to core-android/core-ios and netinfo:

 {
   "name": "experience-A",
   "version": "1.0.0",
   "peerDependencies": {
     "react-native": "^0.63 || ^0.64",
     "react-native-netinfo": "^5.7.1 || ^6.0.0"
   },
+  "rnx-kit": {
+    "reactNativeVersion": "^0.63 || ^0.64",
+    "capabilities": ["core-android", "core-ios", "netinfo"]
+  }
 }

Likewise for experience-B:

 {
   "name": "experience-B",
   "version": "1.0.0",
   "peerDependencies": {
     "react-native": "^0.63",
     "react-native-netinfo": "^5.7.1 || ^6.0.0"
   },
+  "rnx-kit": {
+    "reactNativeVersion": "^0.63",
+    "capabilities": ["core-android", "core-ios", "netinfo"]
+  }
 }

If we run dep-check now, it will complain because experience-B only needs to support react-native-netinfo@^5.7.1:

 {
   "name": "experience-B",
   "version": "1.0.0",
   "peerDependencies": {
     "react-native": "^0.63",
-    "react-native-netinfo": "^5.7.1 || ^6.0.0"
+    "react-native-netinfo": "^5.7.1"
   },
   "rnx-kit": {
     "reactNativeVersion": "^0.63",
     "capabilities": ["core-android", "core-ios", "netinfo"]
   }
 }

We try to avoid breaking changes (major version bumps) within a single profile version. That's why dep-check will recommend 5.x only for react-native 0.63.

If we add webview to capabilities now, dep-check will ask you to add react-native-webview:

 {
   "name": "experience-B",
   "version": "1.0.0",
   "peerDependencies": {
     "react-native": "^0.63",
     "react-native-netinfo": "^5.7.1",
+    "react-native-webview": "^11.4.2"
   },
   "rnx-kit": {
     "reactNativeVersion": "^0.63",
     "capabilities": ["core-android", "core-ios", "netinfo", "webview"]
   }
 }

The user need not know what package to use, only the desired feature.

Let's move on to configuring our app:

 {
   "name": "app",
   "version": "1.0.0",
   "dependencies": {
     "experience-A": "^1.0.0",
     "experience-B": "^1.0.0",
     "react-native": "^0.63.2"
   },
+  "rnx-kit": {
+    "reactNativeVersion": "^0.63",
+    "kitType": "app",
+    "capabilities": ["core-android", "core-ios"]
+  }
 }

The first thing you should note here is that we need to declare that this is an app by setting "kitType": "app". This will tell dep-check to also scan dependencies. By default, this is set to library.

Running dep-check now, the first thing it does is to scan through all your dependencies and gather all required capabilities. dep-check will then resolve all capabilities, and finally make sure the dependencies section in package.json contains all the needed packages and at the correct versions. In our example, our list of capabilities will contain ["netinfo", "webview"]. dep-check sees that there are missing dependencies in your package.json and will output an error message telling you to add them:

 {
   "name": "app",
   "version": "1.0.0",
   "dependencies": {
     "experience-A": "^1.0.0",
     "experience-B": "^1.0.0",
     "react-native": "^0.63.2",
+    "react-native-netinfo": "^5.7.1",
+    "react-native-webview": "^11.4.2"
   },
   "rnx-kit": {
     "reactNativeVersion": "^0.63",
     "capabilities": ["core-android", "core-ios"]
   }
 }

Re-running the command with --write will let dep-check add them for you.

dep-check makes sure that your declared dependencies always matches your list of capabilities. It will make sure that your dependencies are declare in the right sections, i.e. under dependencies if you're an app, and under peerDependencies if you're a library. It will also report partial ones, meaning it will catch scenarios such as when you declare support for 0.63 and 0.64, but are missing react-native-netinfo@^6.0.0.

Zero-config

dep-check is currently opt-in. Packages need to have a configuration that dep-check can run against. However, there is still a need to align packages across repositories without having to configure all packages. dep-check should still be useful without a configuration.

• --init — When configuring a package, it can be cumbersome to know what packages map to what capabilities. --init is a best-effort command that scans all your dependencies and adds a configuration with all the capabilities it thinks are required. You'll likely have to clean up the list, but at least you won't have to start from scratch.
• --vigilant — Without configuring any packages, you can still benefit from dep-check with --vigilant. This mode will scan all dependencies and make sure that their dependencies align with the specified profiles. For instance, --vigilant 0.63,0.64 will compare dependencies against all known modules in profile version 0.63 and 0.64.

Extensions

The list of capabilities may be limited for some usage scenarios. dep-check therefore also allows users to specify additional profiles via configuration, customProfiles, or the equivalent flag, --custom-profiles. The value can be a path to a .js, .json, or module name, e.g. my-custom-capability-resolver, and must default export an object containing profiles keyed by its version number. Example:

module.exports = {
  "0.63": {
    "my-capability": {
      name: "my-module",
      version: "1.0.0",
    },
  },
  "0.64": {
    "my-capability": {
      name: "my-module",
      version: "1.1.0",
    },
  },
};

The profiles are appended to the default ones and may override capabilities. This format is explicitly chosen to be compatible with --vigilant.

Alternatives

• peerDependencies — What's the difference between dep-check and just using the peerDependencies field in package.json?
  • JS package managers are inconsistent when it comes to installing peer dependencies. npm has been back and forth on this. Yarn only emits warnings when they are unsatisfied. The only sure way to get them installed is ensure that the dependencies are added appropriately. However, people tend to ignore warnings in our experience.
  • There is no central control over what gets added to peerDependencies. One package could add react-native-webview@^11.4.2, while another has react-native-webview@^10.10.2. Or worse, they could be adding them under dependencies instead, potentially causing two copies to be bundled with your app.
  • Similarly, package managers don't care whether you're using @react-native-community/netinfo or react-native-netinfo.
• syncpack — syncpack is a tool to manage dependencies within a monorepo. It has some overlap with dep-check but doesn't cover everything we need. In particular:
  • It doesn't have a central repository of dependencies, so it cannot align multiple repositories on the same packages and versions for the same set of capabilities.
  • From a cursory glance, it doesn't allow packages to support multiple versions of react-native.
  • It supports version groups, which may be useful for some usage scenarios, but are potentially dangerous within react-native repos.