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External Dependencies
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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.
Atlas 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.
Add an External Package
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.
Add Packages by Name and Version
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.
Upload a Dependency Directory
You can upload a zipped node_modules directory of packages to your
app. Zipped dependency directories may not exceed 15MB.
Locally Install External Dependencies
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.
Create a Dependency Archive
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.
Upload the Dependency Archive
Once you've created an archive containing your dependencies, you can upload your
dependency archive using the App Services UI or realm-cli:
Import a Package in a Function
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.
Import a Full Module
exports = () => { const R = require("ramda"); return R.map(x => x*2, [1,2,3]); }
Import a Module Subfolder
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); };