Struct fastly::Backend

pub struct Backend { /* private fields */ }

A named backend.

This represents a backend associated with a service that we can send requests to, potentially caching the responses received.

Backends come in one of two flavors:

• Static Backends: These backends are created using the Fastly UI or API, and are predefined by the user. Static backends have short names (see the precise naming rules in Backend::from_name) that are usable across every session of a service.
• Dynamic Backends: These backends are created programmatically using the experimental crate::experimental::BackendExt API. They are defined at runtime, and may or may not be shared across sessions depending on how they are configured.

To use a backend, pass it to the crate::Request::send mathod. Alternatively, the following values can be automatically coerced into a backend for you, without the need to explicitly create a Backend object, although they may all induce panics:

• Any string type (&str, String, or &String) will be automatically turned into the static backend of the same name.

Using Static Backends

As stated at the top level, the following snippet is a minimal program that resends a request to a static backend named “example_backend”:

use fastly::{Error, Request, Response};

#[fastly::main]
fn main(ds_req: Request) -> Result<Response, Error> {
    Ok(ds_req.send("example_backend")?)
}

A safer alternative to this example would be the following:

use fastly::{Backend, Error, Request, Response};

#[fastly::main]
fn main(ds_req: Request) -> Result<Response, Error> {
    match Backend::from_name("example_backend") {
       Ok(backend) => Ok(ds_req.send(backend)?),
       Err(_) => {
            // custom backend failure response
            unimplemented!()
       }
    }
}

as this version allows you to handle backend errors more cleanly.

Validating Support for Dynamic Backends

Since dynamic backends are only enabled for some services, it may be particularly useful to ensure that dynamic backends are supported in your Compute@Edge service. The easiest way to do so is to try to create a dynamic backend, and then explicitly check for the crate::experimental::BackendCreationError::Disallowed code, as follows:

use fastly::{Backend, Error, Request, Response};
use fastly::experimental::{BackendExt, BackendCreationError};

#[fastly::main]
fn main(ds_req: Request) -> Result<Response, Error> {
    match Backend::builder("custom_backend", "example.org:993").finish() {
        Ok(backend) => Ok(ds_req.send(backend)?),
        Err(BackendCreationError::Disallowed) => {
           // custom code ofr handling when dynamic backends aren't supported
           unimplemented!()
        }
        Err(err) => {
           // more specific logging/handling for backend misconfigurations
           unimplemented!()
        }
    }
}

Implementations

impl Backend

pub fn from_name(s: &str) -> Result<Self, BackendError>

Get a backend by its name.

This function will return a BackendError if an invalid name was given.

Backend names:

• cannot be empty
• cannot be longer than 255 characters
• cannot ASCII control characters such as '\n' or DELETE.
• cannot contain special Unicode characters
• should only contain visible ASCII characters or spaces

Future versions of this function may return an error if your service does not have a backend with this name.

pub fn name(&self) -> &str

Get the name of this backend.

pub fn into_string(self) -> String

Turn the backend into its name as a string.

Trait Implementations

impl BackendExt for Backend

fn builder(name: impl ToString, target: impl ToString) -> BackendBuilder

Create a new dynamic backend builder.

fn is_healthy(&self) -> Result<BackendHealth, Error>

Return the health of the backend if configured and currently known.

impl Clone for Backend

fn clone(&self) -> Backend

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Backend

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Backend

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl FromStr for Backend

type Err = BackendError

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Hash for Backend

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where
    H: Hasher,
    Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Backend

fn cmp(&self, other: &Backend) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere
    Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval.

impl PartialEq<Backend> for Backend

fn eq(&self, other: &Backend) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd<Backend> for Backend

fn partial_cmp(&self, other: &Backend) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Eq for Backend

impl StructuralEq for Backend

impl StructuralPartialEq for Backend

impl<'a> ToBackend for &'a Backend

impl ToBackend for Backend