flix-tech / guzzle-circuit-breaker-middleware
A Guzzle 6 middleware to integrate `ejsmont-artur/php-circuit-breaker`
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Requires
- ejsmont-artur/php-circuit-breaker: ~0.1
- guzzlehttp/promises: ~1.2
- psr/http-message: ~1.0
Requires (Dev)
- friendsofphp/php-cs-fixer: ~2.0
- guzzlehttp/guzzle: ~6.2
- phpstan/phpstan: ~0.7
- phpunit/phpunit: ~6.0
This package is auto-updated.
Last update: 2022-05-26 15:26:04 UTC
README
This is a Guzzle 6 middleware that integrates https://github.com/ejsmont-artur/php-circuit-breaker.
Contents
Requirements
Dependencies
Dependency | Version | Reason |
---|---|---|
php |
~7.0 | Anything lower has (almost) reached EOL |
guzzlephp/promises |
~6.2 | Middlewares pass Promises around |
psr/http-message |
~1.0 | Standardization, doh |
ejsmont-artur/php-circuit-breaker |
~0.1 | Simple and robust Circuit Breaker implementation for PHP |
Installation
This library is installed via composer
.
composer require "flix-tech/guzzle-circuit-breaker-middleware=~1.0"
Usage
NOTE It is recommended that this middleware is on top of the stack so that if a service is unavailable, it can instantly reject without going further down the chain.
With the default configuration, this middleware will inspect the PSR-7 requests for either a transport option key
"circuit_breaker.requested_service_name"
exposed via Middleware::CB_TRANSFER_OPTION_KEY
in the request options
array, or a request header "X-CB-Service-Name"
exposed via Middleware::CB_SERVICE_NAME_HEADER
. You can pass an own
service name extractor callable that takes the form f(RequestInterface $request, array $requestOptions): string
.
The service name will be used to look up the
availability in the circuit breaker. If it is not available, it will be instantly rejected with a
CircuitBreakerIsClosedException
.
If the request was successful, the middleware will report a success to the circuit breaker for the given service. Otherwise it will report a failure and pass the rejection further down the chain.
You can pass a custom exception map into the middleware with which you can control which exception types and values
should actually trigger a failure report. I.e. a 404 might be a failed configuration issue and might not trigger failure
reports. The exception map callback takes the form f($rejectedValue): bool
.
Example
<?php use Ejsmont\CircuitBreaker\Factory; use FlixTech\CircuitBreakerMiddleware\Middleware; use GuzzleHttp\Client; use GuzzleHttp\Exception\RequestException; use GuzzleHttp\HandlerStack; use GuzzleHttp\Handler\CurlHandler; use Psr\Http\Message\RequestInterface; $circuitBreaker = Factory::getSingleApcInstance(); $serviceNameExtractor = function (RequestInterface $request, array $options) { if (\array_key_exists('my_custom_option_key', $options)) { return $options['my_custom_option_key']; } return null; }; $exceptionMap = function ($rejectedValue) { if ($rejectedValue instanceof RequestException && $rejectedValue->getResponse()) { return 404 !== $rejectedValue->getResponse()->getStatusCode(); } return true; }; $middleware = new Middleware( $circuitBreaker, $serviceNameExtractor, $exceptionMap ); $handlerStack = HandlerStack::create(new CurlHandler()); $handlerStack->push($middleware); $client = new Client(['handler' => $handlerStack]);
Testing
To run the tests, just run ./vendor/bin/phpunit
from the root of the project after installing the dev requirements.
Contributing
In order to contribute to this library, follow this workflow:
- Fork the repository
- Create a feature branch
- Work on the feature
- Run tests to verify that the tests are passing
- Open a PR to the upstream
master
branch - See any Travis CI messages popping up on your PR
- Be happy about contributing to open source!