ZF2 Zend Logger - Filters by priority

Question

I'm using the Zend Logger with following configuration in the module_config.php:

'log' => [
    \Base\Log\ConsoleLoggerAwareInterface::class => [
        'writers' => [
            'standard-output' => [
                'name' => 'stream',
                'options' => [
                    'stream' => 'php://output',
                ],
            ],
        ],
    ],
]

But as it is I can't influence the log to filter or suppress messages. The goal is to improve the logging to be smarter.

I think I need to add a filter to the writer but I can't find an example how to do that in the module_config.php.

Is there also a way to call a script (e.g. from within a cron) by using a verbosity level?

I hope you know what I'm trying to achive.

Edit:

I have this example in my code:

$this->consoleLogger->emerg('EMERG');
$this->consoleLogger->alert('ALERT');
$this->consoleLogger->crit('CRIT');
$this->consoleLogger->err('ERR');
$this->consoleLogger->warn('WARN');
$this->consoleLogger->notice('NOTICE');
$this->consoleLogger->info('INFO');
$this->consoleLogger->debug('DEBUG');

Should it then not output the filtered ones?

Answer 1

Q: How to filter a Log Writer to a specific error level?

Add a filters key to the particular writer's configuration. Here's direct instantiation to remove any configuration peculiarities: this outputs only "WARN" and "EMERG" messages:

$config = [
    'writers' => [
        'standard-output' => [
            'name' => 'stream',
            'options' => [
                'stream' => 'php://output',
                'filters' => \Zend\Log\Logger::WARN,
            ],
        ],
    ],
];

$logger = new \Zend\Log\Logger($config);
$logger->emerg('EMERG');
$logger->warn('WARN');
$logger->debug('DEBUG');

Adding the filters configuration to your modules_config.php should have a similar effect. If not, check your zend-log version (with eg composer show) and advise.

---

Q: How to change error level filter with the -v command line parameter?

AFAIK, there is no automatic way to bind the standard verbose flag (-v) with a particular logging level. So you'll have to write your own filter. One thing that's neat to know is that the filters key can take:

• an int (as done above, which translates to the built-in log level);
• a string (corresponding to a class name implementing \Zend\Log\Filter\FilterInterface);
• an object (instance of \Zend\Log\Filter\FilterInterface);
• or an array of these.

You can use this flexibility to solve your need of binding a command line parameter to a log value. Here is a custom class that shows emergency events by default, but for every v on the command line increases the shown priority:

class CliLoggingFilter implements \Zend\Log\Filter\FilterInterface
{
    public function __construct()
    {
        $this->level = \Zend\Log\Logger::EMERG;
        if (array_key_exists('v', $args = getopt('v'))) {
            $this->level += count($args['v']);
        }
    }

    public function filter(array $event)
    {
        return ($event['priority'] <= $this->level);
    }
}

You'd then have a configuration like: 'filters' => CliLoggingFilter::class.

$ php public/index.php
2016-07-25T10:57:28-04:00 EMERG (0): EMERG
$ php public/index.php -vvvv
2016-07-25T10:57:32-04:00 EMERG (0): EMERG
2016-07-25T10:57:32-04:00 WARN (4): WARN
$ php public/index.php -vvvvvvv
2016-07-25T10:57:34-04:00 EMERG (0): EMERG
2016-07-25T10:57:34-04:00 WARN (4): WARN
2016-07-25T10:57:34-04:00 DEBUG (7): DEBUG

---

Q: How to change all routes to use -v?

AFAIK, there is no way to specify a global command line parameter. You need to either (a) update all your console routes to accept the argument or (b) pass the log level a different way.

Updating all your routes isn't terribly hard. You can define a variable that holds the value and then include that in the configuration, like so:

$globalConsoleRouteParams = '[--verbose|-v]';
return [ 'console' => 'router' => 'routes' => [
    'foo' => [ 'options' => [ 'route' => "foo $globalConsoleRouteParams ..." ] ],
    'bar' => [ 'options' => [ 'route' => "bar $globalConsoleRouteParams ..." ] ],
    // ...
]];

Alternatively, you could use say environment variables to pass your desired log level, plus perhaps any additional configuration you might desire. Modifying our earlier example:

class CliLoggingFilter implements \Zend\Log\Filter\FilterInterface
{
    public function __construct()
    {
        $this->level = \Zend\Log\Logger::EMERG;
        if (false !== ($level = getenv('LOG_LEVEL'))) {
            $this->level = $level;
        }
    }
    // ...
}

Then it may be invoked like

$ LOG_LEVEL=7 php index.php foo