Using Guzzle4 as a service in Symfony 2.x project with logging via Monolog

config.yml

# Sometimes is it is required to add logging of all guzzle requests into log file via Monolog
# You need to add https://github.com/guzzle/log-subscriber to your project
 
# app/config/config.yml
 
monolog:
    channels: ["guzzle"]
    handlers:
        main:
            channels: ["!guzzle"]
        guzzle:
            type: stream
            path: "%kernel.logs_dir%/guzzle.log" # path to custom log file
            channels: [guzzle]

services.yml

# services.yml in your bundle
 
parameters:
    acme.request.client.class: GuzzleHttp\Client
    acme.request.emitter.class: GuzzleHttp\Event\Emitter
    acme.guzzle.log.subscriber.class: GuzzleHttp\Subscriber\Log\LogSubscriber
 
services:
    acme.request.client:
        class: %acme.request.client.class%
        arguments:
            - { base_url: 'http://path.to.api', defaults: { headers: { Accept: "application/xml" } }, emitter: @acme.request.emitter }
 
    acme.request.emitter:
        class: %acme.request.emitter.class%
        calls:
            - [attach, [@acme.guzzle.log.subscriber]]
        tags:
            - { name: guzzle.client }
 
    acme.guzzle.log.subscriber:
        class: %acme.guzzle.log.subscriber.class%
        arguments:
            - @monolog.logger.guzzle
            - ">>>>>>>>\n{request}\n<<<<<<<<\n{response}\n--------\n{error}" # not mandatory parameter - log format, copy pasted from https://github.com/guzzle/log-subscriber/blob/master/src/Formatter.php#L39 
        tags:
            - { name: guzzle.client }