<<../../_common/intro/_packages_intro.md>>
<<../../_common/intro/_packages_serving.md>>
<<../../_common/intro/_packages_storing.md>>
So far in this codelab, you‘ve been experiencing on demand software delivery to your device and you probably didn’t even know it! In this exercise, you'll peel back the covers and see the details of how packages are delivered and stored on a Fuchsia device.
<<../_common/_restart_femu.md>>
Run the following command to start a package server and enable the emulator to load software packages:
fx serve-updates
The command prints output similar to the following, indicating the server is running and has successfully registered the emulator as a target device:
[serve-updates] Discovery... [serve-updates] Device up [serve-updates] Registering devhost as update source [serve-updates] Ready to push packages! [serve-updates] Target uptime: 139 [pm auto] adding client: [fe80::5888:cea3:7557:7384%qemu]:46126 [pm auto] client count: 1
The fx serve-updates command runs a local package server used to deliver packages to the target devices. By default, this server runs at on port 8083.
Open a browser to http://localhost:8083. This loads an HTML page listing all the packages currently available in the package repository. Each one of these are packages that can be delivered to the device.
Packages are resolved and loaded on demand by a Fuchsia device. Take a look at this in action with the bouncing_ball example package.
From the device shell prompt, you can confirm whether a known package is currently on the device:
fx shell pkgctl pkg-status fuchsia-pkg://fuchsia.com/bouncing_ball
Package in registered TUF repo: yes (merkle=ef65e2ed...) Package on disk: no
Open a new terminal and begin streaming the device logs for pkg-resolver:
ffx log --filter pkg-resolver
This shows all the instances where a package was loaded from the package server.
From the device shell prompt, attempt to resolve the package:
fx shell pkgctl resolve fuchsia-pkg://fuchsia.com/bouncing_ball
Notice the new lines added to the log output for pkg-resolver:
[core/pkg-resolver][pkg-resolver][I] Fetching blobs for fuchsia-pkg://google3-devhost/bouncing_ball: [ e57c05aa909bcb38ca452d31abfbf9cc1d099751c9cd644b4d40cbf64e2af48b, ] [core/pkg-resolver][pkg-resolver][I] resolved fuchsia-pkg://fuchsia.com/bouncing_ball as fuchsia-pkg://google3-devhost/bouncing_ball to 4ca324998ae9679241c74d2d9d9779fe86c79e2fa1f1627d941a37e987215895 with TUF
From the device shell prompt, check the package status again on the device:
fx shell pkgctl pkg-status fuchsia-pkg://fuchsia.com/bouncing_ball
Package in registered TUF repo: yes (merkle=ef65e2ed...) Package on disk: yes (path=/pkgfs/versions/ef65e2ed...)
Fuchsia resolved the package and loaded it from the local TUF repository on demand!
Now that the bouncing_ball package has successfully been resolved, you can explore the package contents. Once resolved, the package is referenced on the target device using its content address.
From the device shell prompt, use the pkgctl get-hash command to determine the package hash for bouncing_ball:
fx shell pkgctl get-hash fuchsia-pkg://fuchsia.com/bouncing_ball
The command returns the unique package hash:
ef65e2ed...
Provide the full package hash to the pkgctl open command to view the package contents:
fx shell pkgctl open {{ '<var>' }}ef65e2ed...{{ '</var>' }}
opening ef65e2ed... with the selectors [] package contents: /bin/bouncing_ball /lib/ld.so.1 /lib/libasync-default.so /lib/libbackend_fuchsia_globals.so /lib/libc++.so.2 /lib/libc++abi.so.1 /lib/libfdio.so /lib/libsyslog.so /lib/libunwind.so.1 /meta/bouncing_ball.cmx /meta/contents /meta/package
This lists the package metadata and each of the content BLOBs in the package. You can bin/ entries for executables, lib/ entries for shared library dependencies, additional metadata and resources.
Congratulations! You now have a better understanding of what makes Fuchsia unique and the goals driving this new platform's design.
In the next module, you'll learn more about the Fuchsia open source project and the tools used to build and customize the system:
Building Fuchsia
