Files
firezone/rust/headless-client
Thomas Eizinger 18ec6c6860 refactor(rust): move service implementation to GUI client (#9045)
The module and crate structure around the GUI client and its background
service are currently a mess of circular dependencies. Most of the
service implementation actually sits in `firezone-headless-client`
because the headless-client and the service share certain modules. We
have recently moved most of these to `firezone-bin-shared` which is the
correct place for these modules.

In order to move the background service to `firezone-gui-client`, we
need to untangle a few more things in the GUI client. Those are done
commit-by-commit in this PR. With that out the way, we can finally move
the service module to the GUI client; where is should actually live
given that it has nothing to do with the headless client.

As a result, the headless-client is - as one would expect - really just
a thin wrapper around connlib itself and is reduced down to 4 files with
this PR.

To make things more consistent in the GUI client, we move the `main.rs`
file also into `bin/`. By convention `bin/` is where you define binaries
if a crate has more than one. cargo will then build all of them.

Eventually, we can optimise the compile-times for `firezone-gui-client`
by splitting it into multiple crates:

- Shared structs like IPC messages
- Background service
- GUI client

This will be useful because it allows only re-compiling of the GUI
client alone if nothing in `connlib` changes and vice versa.

Resolves: #6913
Resolves: #5754
2025-05-08 13:22:09 +00:00
..

headless-client

This crate acts as the CLI / headless Client, and the privileged tunnel service for the GUI Client, for both Linux and Windows.

It is built as:

  • headless-client to act as the Linux / Windows headless Client
  • firezone-headless-client to act as the Linux tunnel service, Windows headless Client, or Windows tunnel service

In general, the brand name should be part of the file name, but the OS name should not be.

Running

To run the headless Client:

  1. Generate a new Service account token from the "Actors -> Service Accounts" section of the admin portal and save it in your secrets manager. The Firezone Linux client requires a service account at this time.
  2. Ensure /etc/dev.firezone.client/token is only readable by root (i.e. chmod 400)
  3. Ensure /etc/dev.firezone.client/token contains the Service account token. The Client needs this before it can start
  4. Set FIREZONE_ID to a unique string to identify this client in the portal, e.g. export FIREZONE_ID=$(uuidgen). The client requires this variable at startup.
  5. Set LOG_DIR to a suitable directory for writing logs
    export LOG_DIR=/tmp/firezone-logs
    mkdir $LOG_DIR
    
  6. Now, you can start the client with:
./firezone-headless-client standalone

If you're running as an unprivileged user, you'll need the CAP_NET_ADMIN capability to open /dev/net/tun. You can add this to the client binary with:

sudo setcap 'cap_net_admin+eip' /path/to/firezone-headless-client

Building

Assuming you have Rust installed, you can build the headless Client with:

cargo build --release -p firezone-headless-client

The binary will be in target/release/firezone-headless-client

The release on Github are built with musl. To build this way, use:

rustup target add x86_64-unknown-linux-musl
sudo apt-get install musl-tools
cargo build --release -p headless-client --target x86_64-unknown-linux-musl

Files

  • /etc/dev.firezone.client/token - The service account token, provided by the human administrator. Must be owned by root and have 600 permissions (r/w by owner, nobody else can read) If present, the tunnel will ignore any GUI Client and run as a headless Client. If absent, the tunnel will wait for commands from a GUI Client
  • /usr/bin/firezone-headless-client - The tunnel binary. This must run as root so it can modify the system's DNS settings. If DNS is not needed, it only needs CAP_NET_ADMIN.
  • /usr/lib/systemd/system/firezone-headless-client.service - A systemd service unit, installed by the deb package.
  • /var/lib/dev.firezone.client/config/firezone-id - The device ID, unique across an organization. The tunnel will generate this if it's not present.