Expand description
Flytrap is a crate for reading the Fly.io runtime environment.
- Read Fly.io environment variables like
$FLY_PUBLIC_IP
into astruct
- Query Fly.io internal DNS addresses like
top3.nearest.of.<app>.internal
- Query the Fly.io machines API
- Parse Fly.io request headers like
Fly-Client-IP
(into anIpAddr
) - Turn Fly.io region codes like
ord
into names like “Chicago” and lat/long coordinates
A demo app is available at flytrap.fly.dev which shows this crate’s capabilities.
§Usage
§Placement
The Placement
type gives access to Fly.io runtime environment
variables like $FLY_PUBLIC_IP
and $FLY_REGION
.
use flytrap::{Placement, Machine};
fn main() -> Result<(), Box<dyn std::error::Error>> {
let runtime = Placement::current()?;
println!("Fly.io app: {}", runtime.app);
println!(" region: {}", runtime.location);
if let Some(Machine{ id, memory: Some(memory), image: Some(image), .. }) = runtime.machine {
println!(" machine: {id} ({memory} MB) running {image}");
}
if let Some(public_ip) = runtime.public_ip {
println!(" public IP: {}", public_ip);
}
println!("private IP: {}", runtime.private_ip);
Ok(())
}
§Regions
Flytrap models Fly.io regions as an enum
:
use flytrap::{City, Placement, Region};
fn main() -> Result<(), Box<dyn std::error::Error>> {
let runtime = Placement::current()?;
let region = runtime.region().unwrap_or(Region::Guadalajara);
show(region);
Ok(())
}
fn show(region: Region) {
let City { name, country, geo } = region.city;
println!("Running in {name} ({country}) @ {}, {}", geo.x(), geo.y());
}
Regions implement Ord
, and sort geographically:
use flytrap::Region::*;
let mut regions = [Bucharest, Chicago, HongKong, Johannesburg,
LosAngeles, Madrid, Santiago, Tokyo];
regions.sort();
assert_eq!(regions, [LosAngeles, Chicago, Santiago, Madrid,
Bucharest, Johannesburg, HongKong, Tokyo]);
§DNS queries
Create a Resolver
in order to query the Fly.io .internal
DNS zone.
use flytrap::Resolver;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let resolver = Resolver::new()?;
// Discover all instances of the currently-running app
let peers = resolver.current()?.peers().await?;
for peer in peers {
println!("peer {} in {} @ {}", peer.id, peer.location, peer.private_ip);
}
Ok(())
}
§Machines API requests
Create an api::Client
to send requests to the machines API
use std::env;
use flytrap::api::Client;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let token = env::var("FLY_API_TOKEN")?;
let client = Client::new(token);
// Discover other instances of the currently-running app
let peers = client.peers().await?;
for peer in peers {
println!("peer {} in {} is {:?}", peer.name, peer.location, peer.state);
}
Ok(())
}
§HTTP headers
The http
module contains typed Header
implementations of
the HTTP request headers added by Fly.io edge proxies, like
Fly-Client-IP
.
§Features
Flytrap’s compilation can be controlled through a number of Cargo features.
api
: Enable the client for the Fly.io machines APIdns
: EnableResolver
for querying Fly.io internal DNS, viahickory-dns
⭐detect
: Enable automaticResolver
setup for Wireguard VPN clients, viaif-addrs
⭐️environment
: Enable code which reads Fly.io environment variables like$FLY_PUBLIC_IP
⭐️http
: Enable types for HTTPheaders
likeFly-Client-IP
⭐️nightly
: Enable code which is only accepted by nightly Rust toolchainsregions
: Enable theRegion
type andRegionDetails
structures ⭐️serde
: Enable Serde#[derive(Deserialize, Serialize)]
on this crate’s typessystem-resolver
: Enable theResolver::system()
constructor, which reads/etc/resolv.conf
(Features marked with a ⭐️ are enabled by default.)
Modules§
- api
api
Access the Fly.io Machines API. - http
http
Structs§
- AppResolver
dns
Query the Fly.io internal DNS records for a particular app. - City
regions
Describes a city where a Fly.io region is hosted. - Instance
dns
The result type of_instances.internal
TXT queries. - Information about the Fly.io Machine on which the current process is running.
- Node
dns
- Peer
dns
A fully-resolvedNode
whose private IP address is known. - Details how the current process is running in the Fly.io runtime environment.
- RegionCode
regions
An unrecognized Fly.io region code. - RegionDetails
regions
Attributes of a knownRegion
. - Resolver
dns
Query the Fly.io internal DNS records.
Enums§
- An error in a
Resolver
operation. - Location
regions
A Fly.io point of presence. - Region
regions
- RegionError
regions
An error parsing aRegion
orRegionCode
.
Functions§
- Return the Fly.io DNS server address which serves a given
local
Fly.io Wireguard address. - hosted
environment
Checks to see if the current process appears to be running in the Fly.io runtime environment, based on the presence of certain$FLY_
environment variables. - private_address
detect
orenvironment
Read the$FLY_PRIVATE_IP
environment variable, if set to a valid IPv6 address.