This doc will guide you through some of the features of ffx. For an overview
of the design and components of ffx, see the ffx overview.
Contacting the ffx team
If you discover possible bugs or have questions or suggestions, file a bug.
Prerequisites
To follow the examples in this doc, you'll need a Fuchsia device running. If you don't have a physical device connected, you can use an emulator.
To start an emulator with networking enabled but without graphical user
interface support, run ffx emu start --headless.
For more information on configuring the emulator see, Start the Fuchsia emulator.
Your device must be running a core
product configuration
or a product configuration that extends core (such as workstation_eng).
Optionally, you can run ffx log, which will provide some additional information
about the interactions between ffx and your Fuchsia target device.
Introduction
After following all the prerequisites, run the following in a terminal:
fx ffx help
This will list all of the available ffx subcommands. You'll see something
like:
Usage: ffx [-c <config>] [-e <env>] [-t <target>] [<command>] [<args>]
Fuchsia's developer tool
Options:
-c, --config override default configuration
-e, --env override default environment settings
-t, --target apply operations across single or multiple targets
-o, --log-output specify destination of log output
--help display usage information
Commands:
component Discover and manage components
config View and switch default and user configurations
daemon Interact with/control the ffx daemon
diagnostic Run diagnostic tests on Fuchsia targets
docs View suite of docs for ffx and for Fuchsia
doctor Run common checks for the ffx tool and host environment
emulator Start and manage Fuchsia emulators
overnet Interact with the Overnet mesh
package Create and publish Fuchsia packages
sdk Modify or query the installed SDKs
target Interact with a target device or emulator
version Print out ffx tool and daemon versions
You can use fx ffx help <subcommand> or fx ffx <subcommand> --help to see
more about any subcommand.
Interacting with target devices
In a terminal, run the following:
fx ffx target list
You'll see a list of devices that ffx has discovered. For example, with a
single emulator running, output looks like:
NAME SERIAL TYPE STATE ADDRS/IP RCS
fuchsia-emulator <unknown> Unknown Product [fe80::5054:ff:fe63:5e7a%4] N
RCS: Indicates whether there is a reachable instance of the Remote Control
Service (RCS) running on the device.
In order to get ffx to automatically connect to a device, you must either have
set the target's nodename to be the default target, or attempt to interact with the
device.
To set the target to be the default, run:
fx ffx target default set $NODENAME
If the default target has been set prior to starting the daemon, waiting a few seconds
should yield a change to the RCS status to show Y.
If the default target has been set after starting the daemon, attempting to interact with the target should be sufficient to kick off a connection, like the following
fx ffx component list
Then the next time you list targets you should see that an RCS connection
is active.
$ fx ffx target list
NAME SERIAL TYPE STATE ADDRS/IP RCS
fuchsia-emulator <unknown> Unknown Product [fe80::5054:ff:fe63:5e7a%4] Y
If a target has been set as default there will be a * next to it.
If you had ffx log running, you should also see something like the following in
the logs:
[00009.776170][28540][28542][remote-control, remote_control_bin] INFO: published remote control service to overnet
NOTE: if the RCS column remains N for an extended amount of time and you have
already set this target's nodename to target.default before initially starting
ffx, reach out to the ffx team.
On Default Targets
Above we covered setting the default target using the command
fx ffx target default set
It is also possible to set the default target on a per-command basis using the
--target flag like so.
fx ffx --target $NODENAME component list
Interacting with multiple devices
TODO: fill this out.
Controlling the state of target devices
You can use the target off and target reboot subcommands to power-off or
reboot a device, respectively.
ffx logs
Destination
Logs normally go to a cache directory (on Linux, usually
$HOME/.local/share/Fuchsia/ffx/cache/logs).
The location can be found by running
fx ffx config get log.dir
However, the location can be overridden with -o/--log-output <destination>,
where <destination> can be a filename, or stdout (by specifying stdout
or -), or stderr (by specifying stderr).
Log Level
The debugging level can be specified with -l/--log-level <level>,
where <level> is one of off, error, warn, info, debug, or trace.
The default is info.
It can also be permanently set by configuring log.level, e.g.:
fx ffx config set log.level debug
Interactive Use
A common use of the above options is to see debugging for a specific command:
fx ffx -l debug -o - target echo
The above command will produce debugging logs on the command line as part of the invocation.
Target Levels
Specific log "targets" can have a different level, by specifying
configuration entries under log.target_levels. For instance, to
see debug logs only for analytics:
fx ffx config set log.target_levels.analytics debug
Log "targets" are simply prefixes to a log line.
Configuration
See documentation for the config command.
Interacting with Components
Monikers
Many ffx commands that use components take monikers as a parameter. You can read more about
monikers and their syntax in component moniker documentation.
Finding components
The component list command will output monikers of all components that currently exist
in the component topology.
$ fx ffx component list
/
/bootstrap
/bootstrap/archivist
/bootstrap/base_resolver
/bootstrap/console
/bootstrap/console-launcher
/bootstrap/cr50_agent
/bootstrap/device_name_provider
/bootstrap/driver_index
/bootstrap/driver_manager
/bootstrap/flashmap
/bootstrap/fshost
/bootstrap/fshost/blobfs
/bootstrap/fshost/blobfs/decompressor
...
You can use the component select capability command to search for components that use/expose
a capability with a given name.
The following command will display all components that use/expose the diagnostics capability:
$ fx ffx component capability diagnostics
Exposed:
/bootstrap/archivist
/bootstrap/base_resolver
/bootstrap/driver_manager
/bootstrap/fshost
/bootstrap/fshost/blobfs
/bootstrap/fshost/blobfs/decompressor
/bootstrap/fshost/minfs
/bootstrap/pkg-cache
/bootstrap/power_manager
...
Inspecting a component
You can use the component show command to get detailed information about a specific
component.
component show allows partial matching on URL, moniker and component instance ID.
The following command will display information about the /core/network/dhcpd component:
$ fx ffx component show dhcpd
Moniker: /core/network/dhcpd
URL: #meta/dhcpv4_server.cm
Instance ID: 20b2c7aba6793929c252d4e933b8a1537f7bfe8e208ad228c50a896a18b2c4b5
Type: CML Component
Component State: Resolved
Incoming Capabilities: /svc/fuchsia.net.name.Lookup
/svc/fuchsia.posix.socket.packet.Provider
/svc/fuchsia.posix.socket.Provider
/svc/fuchsia.stash.SecureStore
/svc/fuchsia.logger.LogSink
Exposed Capabilities: fuchsia.net.dhcp.Server
Merkle root: 521109a2059e15acc93bf77cd20546d106dfb625f2d1a1105bb71a5e5ea6b3ca
Execution State: Running
Start reason: '/core/network/netcfg' requested capability 'fuchsia.net.dhcp.Server'
Running since: 2022-09-15 16:07:48.469094140 UTC
Job ID: 28641
Process ID: 28690
Outgoing Capabilities: fuchsia.net.dhcp.Server
Verifying capability routes
You can use the component doctor command to verify that all capabilities
exposed and used by a component are successfully routed.
For example:
$ fx ffx component doctor /bootstrap/archivist
Querying component manager for /bootstrap/archivist
URL: fuchsia-boot:///#meta/archivist.cm
Instance ID: None
Used Capability Error
[✓] fuchsia.boot.ReadOnlyLog N/A
[✓] fuchsia.boot.WriteOnlyLog N/A
[✓] fuchsia.component.DetectBinder N/A
[✓] fuchsia.component.KcounterBinder N/A
[✓] fuchsia.component.PersistenceBinder N/A
[✓] fuchsia.component.SamplerBinder N/A
[✓] fuchsia.sys.internal.ComponentEvent N/A
Provider
[✓] fuchsia.sys.internal.LogConnector N/A
[✓] config-data N/A
Exposed Capability Error
[✓] fuchsia.diagnostics.FeedbackArchive N/A
Accessor
[✓] fuchsia.diagnostics.LegacyMetricsAr N/A
chiveAccessor
[✓] fuchsia.diagnostics.LoWPANArchiveAc N/A
cessor
[✓] diagnostics N/A
[✓] fuchsia.diagnostics.ArchiveAccessor N/A
[✓] fuchsia.diagnostics.LogSettings N/A
[✓] fuchsia.logger.Log N/A
[✓] fuchsia.logger.LogSink N/A
$ fx ffx component doctor /core/feedback
Querying component manager for /core/feedback
URL: fuchsia-pkg://fuchsia.com/forensics#meta/feedback.cm
Instance ID: eb345fb7dcaa4260ee0c65bb73ef0ec5341b15a4f603f358d6631c4be6bf7080
Used Capability Error
[✓] fuchsia.boot.ReadOnlyLog N/A
[✓] fuchsia.boot.WriteOnlyLog N/A
[✓] fuchsia.diagnostics.FeedbackArchive N/A
Accessor
[✓] fuchsia.hardware.power.statecontrol N/A
.RebootMethodsWatcherRegister
[✓] fuchsia.hwinfo.Board N/A
[✓] fuchsia.hwinfo.Product N/A
[✓] fuchsia.metrics.MetricEventLoggerFa N/A
ctory
[✓] fuchsia.net.http.Loader N/A
[✓] fuchsia.process.Launcher N/A
[✓] fuchsia.sysinfo.SysInfo N/A
[✓] fuchsia.ui.activity.Provider N/A
[✗] fuchsia.feedback.DeviceIdProvider `/core/feedback` tried to use `fuchsia.feedback.DeviceIdProvider` from its parent,
but the parent does not offer that capability. Note, use clauses in CML default to
using from parent.
...
Running a component
The component run command can create and launch components in a given isolated collection.
Here's an example of running the Rust hello-world component in the /core/ffx-laboratory
collection. First, you'll need the hello-world package in your universe:
$ fx set <product>.<board> --with //examples/hello_world/rust:hello-world-rust && fx build
...
Then use the component run command to create and launch a component instance from the URL
fuchsia-pkg://fuchsia.com/hello-world-rust#meta/hello-world-rust.cm with the moniker
/core/ffx-laboratory:hello-world-rust:
$ fx ffx component run /core/ffx-laboratory:hello-world-rust fuchsia-pkg://fuchsia.com/hello-world-rust#meta/hello-world-rust.cm
URL: fuchsia-pkg://fuchsia.com/hello-world-rust#meta/hello-world-rust.cm
Moniker: /core/ffx-laboratory:hello-world-rust
Creating component instance...
...
$ fx ffx component show hello-world-rust
Moniker: /core/ffx-laboratory:hello-world-rust
URL: fuchsia-pkg://fuchsia.com/hello-world-rust#meta/hello-world-rust.cm
Type: v2 dynamic component
Execution State: Running
Job ID: 50775
Process ID: 50819
...
Resolving connectivity issues
If you're experiencing problems communicating with a target device using ffx,
you can use the doctor command to diagnose and attempt to resolve them. If you
file a bug that involves a target device, we'll typically ask for the output
from ffx doctor to provide information about where the problem is.
doctor will attempt to communicate with the ffx daemon, killing
and restarting it if needed. If this is successful, it will attempt to SSH into
a target device and start the Remote Control Service.
If you try running ffx doctor under normal circumstances, you should see:
$ fx ffx doctor
Checking for a running daemon...none running.
Attempting to kill any zombie daemons...killed at least one daemon.
Starting a new daemon instance...success
Attempting to connect to the daemon. This may take a couple seconds...success
Attempting to communicate with the daemon...success
Attempting to list targets...success
Attempting to get an RCS connection...success
Attempting to communicate with RCS...success
SUCCESS. You should be able to run ffx commands now.
If doctor fails, it will try to suggest a resolution to the problem. You can file a bug for the ffx team if you
persistently have problems. For example, if doctor is unable to start the RCS,
you would see the following:
$ fx ffx doctor
Checking for a running daemon...found
Attempting to connect to the daemon. This may take a couple seconds...success
Attempting to communicate with the daemon...success
Attempting to list targets...success
Attempting to get an RCS connection...success
Attempting to communicate with RCS...FAILED. Timed out.
Attempt 2 of 3
Attempting to list targets...success
Attempting to get an RCS connection...success
Attempting to communicate with RCS...FAILED. Timed out.
Attempt 3 of 3
Attempting to list targets...success
Attempting to get an RCS connection...success
Attempting to communicate with RCS...FAILED. Timed out.
Connecting to RCS failed after maximum attempts. To resolve this issue, try
rebooting your device. If this persists, please file a bug at the link below
and include 1) all output
above and 2) device syslog if available.Bug link: ...
Testing with ffx
The ffx command is useful when writing integration tests which need to interact
with the Fuchsia environment. However, since ffx is primarily designed for
developers, it inspects the current environment for configuration and also starts
a daemon in the background to coordinate communication with Fuchsia devices. This
makes it more complex to write automated tests that use ffx since the configuration
and daemon should be isolated in order to avoid side effects, or interference from
the global environment.
To achieve this isolation, test authors need to use isolate directories
when running tests which use ffx.
Next steps
- Please provide feedback on this doc by reaching out to the ffx team!
- Learn how to extend
ffx.