docs/Rollup.md

---
title: Rollup
layout: default
stylesheet: docs
---
<!-- *********************
 DO NOT EDIT THIS FILE
  It is a generated build output from Stardoc.
  Instead you must edit the .bzl file where the rules are declared,
  or possibly a markdown file next to the .bzl file
 ********************* -->
# rollup rules for Bazel

The rollup rules run the rollup JS bundler with Bazel.

Wraps the rollup CLI documented at https://rollupjs.org/guide/en/#command-line-reference


## Installation

Add the `@bazel/rollup` npm package to your `devDependencies` in `package.json`.

Your `WORKSPACE` should declare a `yarn_install` or `npm_install` rule named `npm`.
It should then install the rules found in the npm packages using the `install_bazel_dependencies` function.
See https://github.com/bazelbuild/rules_nodejs/#quickstart

This causes the `@bazel/rollup` package to be installed as a Bazel workspace named `npm_bazel_rollup`.


## Installing with self-managed dependencies

If you didn't use the `yarn_install` or `npm_install` rule to create an `npm` workspace, you'll have to declare a rule in your root `BUILD.bazel` file to execute rollup:

```python
# Create a rollup rule to use in rollup_bundle#rollup_bin
# attribute when using self-managed dependencies
nodejs_binary(
    name = "rollup_bin",
    entry_point = "//:node_modules/rollup/bin/rollup",
    # Point bazel to your node_modules to find the entry point
    node_modules = ["//:node_modules"],
)
```

[name]: https://bazel.build/docs/build-ref.html#name
[label]: https://bazel.build/docs/build-ref.html#labels
[labels]: https://bazel.build/docs/build-ref.html#labels


## rollup_bundle

Runs the Rollup.js CLI under Bazel.

See https://rollupjs.org/guide/en/#command-line-reference

Typical example:
```python
load("@npm_bazel_rollup//:index.bzl", "rollup_bundle")

rollup_bundle(
    name = "bundle",
    srcs = ["dependency.js"],
    entry_point = "input.js",
    config_file = "rollup.config.js",
)
```

Note that the command-line options set by Bazel override what appears in the rollup config file.
This means that typically a single `rollup.config.js` can contain settings for your whole repo,
and multiple `rollup_bundle` rules can share the configuration.

Thus, setting options that Bazel controls will have no effect, e.g.

```javascript
module.exports = {
    output: { file: 'this_is_ignored.js' },
}
```

You must determine ahead of time whether Rollup needs to produce a directory output.
This is the case if you have dynamic imports which cause code-splitting, or if you
provide multiple entry points. Use the `output_dir` attribute to specify that you want a
directory output.
Rollup's CLI has the same behavior, forcing you to pick `--output.file` or `--output.dir`.

To get multiple output formats, wrap the rule with a macro or list comprehension, e.g.

```python
[
    rollup_bundle(
        name = "bundle.%s" % format,
        entry_point = "foo.js",
        format = format,
    )
    for format in [
        "cjs",
        "umd",
    ]
]
```

This will produce one output per requested format.



### Usage

```
rollup_bundle(name, args, config_file, deps, entry_point, entry_points, format, node_context_data, output_dir, rollup_bin, silent, sourcemap, srcs)
```



#### `name`
(*[name], mandatory*): A unique name for this target.

#### `args`
(*List of strings*): Command line arguments to pass to rollup. Can be used to override config file settings.

These argument passed on the command line before all arguments that are always added by the
rule such as `--output.dir` or `--output.file`, `--format`, `--config` and `--preserveSymlinks` and
also those that are optionally added by the rule such as `--sourcemap`.

See rollup CLI docs https://rollupjs.org/guide/en/#command-line-flags for complete list of supported arguments.

Defaults to `[]`

#### `config_file`
(*[label]*): A rollup.config.js file

Passed to the --config 
See https://rollupjs.org/guide/en/#configuration-files

If not set, a default basic Rollup config is used.

Defaults to `@npm_bazel_rollup//:rollup.config.js`

#### `deps`
(*[labels]*): Other libraries that are required by the code, or by the rollup.config.js

Defaults to `[]`

#### `entry_point`
(*[label]*): The bundle's entry point (e.g. your main.js or app.js or index.js).

This is just a shortcut for the `entry_points` attribute with a single output chunk named the same as the rule.

For example, these are equivalent:

```python
rollup_bundle(
    name = "bundle",
    entry_point = "index.js",
)
```

```python
rollup_bundle(
    name = "bundle",
    entry_points = {
        "index.js": "bundle"
    }
)
```

If `rollup_bundle` is used on a `ts_library`, the `rollup_bundle` rule handles selecting the correct outputs from `ts_library`.
In this case, `entry_point` can be specified as the `.ts` file and `rollup_bundle` will handle the mapping to the `.mjs` output file.

For example:

```python
ts_library(
    name = "foo",
    srcs = [
        "foo.ts",
        "index.ts",
    ],
)

rollup_bundle(
    name = "bundle",
    deps = [ "foo" ],
    entry_point = "index.ts",
)
```

Defaults to `None`

#### `entry_points`
(*<a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: Label -> String</a>*): The bundle's entry points (e.g. your main.js or app.js or index.js).

Passed to the [`--input` option](https://github.com/rollup/rollup/blob/master/docs/999-big-list-of-options.md#input) in Rollup.

Keys in this dictionary are labels pointing to .js entry point files.
Values are the name to be given to the corresponding output chunk.

Either this attribute or `entry_point` must be specified, but not both.

Defaults to `{}`

#### `format`
(*String*): "Specifies the format of the generated bundle. One of the following:

- `amd`: Asynchronous Module Definition, used with module loaders like RequireJS
- `cjs`: CommonJS, suitable for Node and other bundlers
- `esm`: Keep the bundle as an ES module file, suitable for other bundlers and inclusion as a `<script type=module>` tag in modern browsers
- `iife`: A self-executing function, suitable for inclusion as a `<script>` tag. (If you want to create a bundle for your application, you probably want to use this.)
- `umd`: Universal Module Definition, works as amd, cjs and iife all in one
- `system`: Native format of the SystemJS loader

Defaults to `"esm"`

#### `node_context_data`
(*[label]*): Internal use only

Defaults to `@build_bazel_rules_nodejs//internal:node_context_data`

#### `output_dir`
(*Boolean*): Whether to produce a directory output.

We will use the [`--output.dir` option](https://github.com/rollup/rollup/blob/master/docs/999-big-list-of-options.md#outputdir) in rollup
rather than `--output.file`.

If the program produces multiple chunks, you must specify this attribute.
Otherwise, the outputs are assumed to be a single file.

Defaults to `False`

#### `rollup_bin`
(*[label]*): Target that executes the rollup binary

Defaults to `@npm//rollup/bin:rollup`

#### `silent`
(*Boolean*): Whether to execute the rollup binary with the --silent flag, defaults to False.

Using --silent can cause rollup to [ignore errors/warnings](https://github.com/rollup/rollup/blob/master/docs/999-big-list-of-options.md#onwarn) 
which are only surfaced via logging.  Since bazel expects printing nothing on success, setting silent to True
is a more Bazel-idiomatic experience, however could cause rollup to drop important warnings.

Defaults to `False`

#### `sourcemap`
(*String*): Whether to produce sourcemaps.

Passed to the [`--sourcemap` option](https://github.com/rollup/rollup/blob/master/docs/999-big-list-of-options.md#outputsourcemap") in Rollup

Defaults to `"inline"`

#### `srcs`
(*[labels]*): Non-entry point JavaScript source files from the workspace.

You must not repeat file(s) passed to entry_point/entry_points.

Defaults to `[]`