Adding tags

In Open Telemetry, traces and spans can have tags attached. These can be useful to track a system's hostname, internal IP address, or other metadata.

##Manually adding tags

Using our package, you can add tags to traces, by chaining on the tags() method when starting to measure something. These tags will be merged with automatically added tags.

use \Spatie\OpenTelemetry\Facades\Measure;

Measure::start('span name')->tags([
    'tag name' => 'tag value',
])

##Automatically adding tags

This package can automatically add tags to any measurement made. This is done using the tag providers configured in config/open-telemetry.php. A tag providers is any class the implements the Spatie\OpenTelemetry\Support\TagProviders\TagProvider interface.

Here's an example:

use Spatie\OpenTelemetry\Support\TagProviders\TagProvider;

class HostNameTagProvider implements TagProvider
{
    public function tags(): array
    {
        return [
            'host.name' => gethostname(),
        ];
    }
}

This tag provider can be resolved when a trace starts by adding it the trace_tag_providers key in the config/open-telemetry.php config file. If that tag provider should be executed before each span (so each time you can Measure::start()), you should add it to the span_tag_providers key in the config file.