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As relict from very early designs of `connlib`, the `Callbacks` trait is still present and defines how the host app receives events from a running `Session`. Callbacks are not a great design pattern however because they force the running code, i.e. `connlib`s event-loop to execute unknown code. For example, if that code panics, all of `connlib` is taken down. Additionally, not all consumers may want to receive events via callbacks. The GUI and headless client for example already have their own event-loop in which they process all kinds of things. Having to deal with the `Callbacks` interface introduces an odd indirection here. To fix this, we instead return an `EventStream` when constructing a `Session`. This essentially aligns the API of `Session` with that of a channel. You receive two handles, one for sending in commands and one for receiving events. A `Session` will automatically spawn itself onto the given runtime so progress is made even if one does not poll on these channel handles. This greatly simplifies the code: - We get to delete the `Callbacks` interface. - We can delete the threaded callback adapter. This was only necessary because we didn't want to block `connlib` with the handling of the event. By using a channel for events, this is automatically guaranteed. - The GUI and headless client can directly integrate the event handling in their event-loop, without having to create an indirection with a channel. - It is now clear that only the Apple and Android FFI layers actually use callbacks to communicate these events. - We net-delete 100 LoC
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-clientto act as the Linux / Windows headless Clientfirezone-headless-clientto 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:
- 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.
- Ensure
/etc/dev.firezone.client/tokenis only readable by root (i.e.chmod 400) - Ensure
/etc/dev.firezone.client/tokencontains the Service account token. The Client needs this before it can start - Set
FIREZONE_IDto a unique string to identify this client in the portal, e.g.export FIREZONE_ID=$(uuidgen). The client requires this variable at startup. - Set
LOG_DIRto a suitable directory for writing logsexport LOG_DIR=/tmp/firezone-logs mkdir $LOG_DIR - 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.