Packages

A package is the unit of installation on a Fuchsia system. This document describes various workflows for building and installng a package.

The workflows are:

Build a package
Publish a package
Install a package
Run a component from an installed package

For more details, see the help messages from ffx package build help, and ffx repository publish help.

Build a package

To build a package:

Create a meta directory:
```
mkdir -p PACKAGE_DIR/meta
```
Replace PACKAGE_DIR with the staging directory where the package is going to be built.

Set the $META_PACKAGE_FILE environment variable:

export META_PACKAGE_FILE=PACKAGE_DIR/meta/package

Open a text editor and create the $META_PACKAGE_FILE file with the following content:
```
{
  "name": "<intended name of your package here>",
  "version": "0"
}
```
The version number is currently required to be 0.
Save the file and close the text editor.
Create a package build manifest file ($BUILD_MANIFEST_FILE), which provides the paths to all the package content files, and export its path via the variable:
```
export BUILD_MANIFEST_FILE=BUILD_MANIFEST_FILE
```
Each line of a manifest file maps to a file contained in the package and is in the form of destination=source where:
- destination is the path to the file in the final package.
- source is the path to the file on the host machine.
The manifest file must include at least one line for the package ID file, for example:
```
meta/package=/path/to/meta/package
```
Additional files to be added to the package must be listed in the build manifest file in the same way.
Go to the PACKAGE_DIR directory:
```
cd PACKAGE_DIR
```
Generate a package manifest file, which creates the package metadata archive at PACKAGE_DIR/meta.far:
```
ffx package build $BUILD_MANIFEST_FILE -o PACKAGE_DIR --api-level HEAD
```
This command creates the package manifest file implicitly as PACKAGE_DIR/package_manifest.json.

Note that the --api-level is preferably used to target a specific API level, given by a numeric argument. In this example we use HEAD, i.e. the latest in-development API.
Set the $PACKAGE_MANIFEST_FILE environment variable:
```
export PACKAGE_MANIFEST_FILE="PACKAGE_DIR/package_manifest.json"
```
If the contents of the package change, you need to re-run the ffx package build $BUILD_MANIFEST_FILE command.
Create a package archive, which gathers all the package contents into a single distributable file:
```
ffx package archive create -o "PACKAGE_DIR/PACKAGE_NAME.far" "$PACKAGE_MANIFEST_FILE"
```
Replace PACKAGE_NAME with the intended name of the package.

This command creates the package archive as PACKAGE_NAME.far.
Set the$PACKAGE_ARCHIVE environment variable:
```
export PACKAGE_ARCHIVE=PACKAGE_DIR/PACKAGE_NAME.far
```
If the contents of the package change, you need to re-run the ffx package build and ffx package archive create commands.

You have successfully built a package. Now you are ready to publish the package.

Publish a package

To publish a package:

Initialize a directory that serves as a packages repository:
```
ffx repository create REPO
```
This creates a directory structure under the directory REPO which is ready for publishing packages.
Publish package manifests to the repository:
```
ffx repository publish --package $PACKAGE_MANIFEST_FILE REPO
```
ffx repository publish parses $PACKAGE_MANIFEST_FILE and publishes the package in the provided REPO directory.

The --package argument can be repeated. If you run this command multiple times with different package manifests, each instance will be published to the same repository. New versions of the same packages can be published using the same command.
(Optional) Publish package archives to the repository:
```
ffx repository publish --package-archive $PACKAGE_ARCHIVE REPO
```
ffx repository publish parses $PACKAGE_ARCHIVE and publishes the package in the provided REPO directory.

The --package-archive argument can be repeated. If you run this command multiple times with different package archives, each instance will be published to the same repository. New versions of the same packages can be published using the same command.

You have successfully published a package. You are now ready to install a package.

Install a package

To install a package:

Start the package server and serve the repository to the target:
```
ffx repository serve --repository "REPO_NAME" --repo-path "REPO"
```
By default, this starts a repository server on the host machine, listening on port 8083. This introduces the repository to the target as an update source. The --repository "REPO_NAME" is optional, but useful.
(On the target device) Check the configured repository:
```
pkgctl repo -v
```
You should see a repository configured, listing (among other configuration variables) its repository url "repo_url": "fuchsia-pkg://<REPO_NAME>".
(On the target device) Download the package:
```
pkgctl resolve fuchsia-pkg://REPO_NAME/PACKAGE_NAME
```
If the component is not already present on the system, pkgctl downloads the package and places the blobs in the blobFS in the process of resolving. If the package already exists, the updates will be downloaded.

You have successfully installed or updated the package. You are now ready to run a component from the installed package.

Run a component from an installed package

To run the component, use the ffx component run tool. For help: ffx component run --help.

For the url parameter provide a URL in the form of fuchsia-pkg://<REPO_NAME>/<PACKAGE_NAME>#meta/<COMPONENT_NAME>.cm.