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External Dependencies

On this page

  • Add an External Package
  • Add Packages by Name and Version
  • Upload a Dependency Directory
  • Import a Package in a Function
  • Import a Full Module
  • Import a Module Subfolder

An external dependency is a library that includes code that you can't or don't want to implement yourself. For example, you might use an official library for an external service or a custom implementation of a data structure or algorithm.

App Services automatically transpiles dependencies and also supports most built-in Node.js modules.

Note
Create Your Own Modules

Though most npm modules are written by third parties, you can also create and publish your own npm modules to house logic specific to your application. You can make your modules available to the Node.js community or reserve them for private use. For more information, check out npm's guide on Contributing packages to the registry.

To import and use an external dependency, you first need to add the dependency to your application. You can either add packages by name or upload a directory of dependencies.

Important
Override Existing Dependencies

You can only use one method at a time to specify the external packages your app can use. The most recent method that you used to specify dependencies is the source of truth and overrides previous specifications.

For example, a package added by name through the UI overrides any copies of the same package that you've added previously, including those in an uploaded dependency directory.

You can add packages from the npm registry to your app by name. You can either add a specific version or use the latest version.

You can upload a zipped node_modules directory of packages to your app. Zipped dependency directories may not exceed 15MB.

1

To upload external dependencies, you first need a local node_modules folder containing at least one Node.js package. You can use the following code snippet to install a dependency locally you would like to upload:

npm install <package name>

If the node_modules folder does not already exist, this command automatically creates it.

Note
Alternative Methods of Installation

You can also configure a package.json and run the npm install command to install all packages (and their dependencies) listed in your package.json.

To learn more about npm and node_modules, consult the npm documentation.

2

Now that you've downloaded all of your npm modules, you need to package them up in an archive so you can upload them to App Services. Create an archive containing the node_modules folder:

tar -czf node_modules.tar.gz node_modules/
Note
Supported Archive Formats

App Services supports .tar, .tar.gz, .tgz, and .zip archive formats.

3

Once you've created an archive containing your dependencies, you can upload your dependency archive using the Atlas App Services UI or realm-cli:

You can import built-in modules and external packages that you've added to your app and then use them in your functions. To import a package, call require() with the package name from within the function body.

Important
Where Do I Import Modules?

Node.js projects commonly place require() calls in the global scope of each file, but App Services does not support this pattern. You must place App Services require() calls within a function scope.

exports = () => {
const R = require("ramda");
return R.map(x => x*2, [1,2,3]);
}
exports = function(arg){
const cloneDeep = require("lodash/cloneDeep");
var original = { name: "Deep" };
var copy = cloneDeep(original);
copy.name = "John";
console.log(`original: ${original.name}`);
console.log(`copy: ${copy.name}`);
return (original != copy);
};
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