refactor sdk/api logging (#1105)

send errors/warnings/etc by default through PHP's error_log. This gives more control to administrators, since error_log can
be configured to write to any stream (file, stderr, etc). I think it's also less surprising for people trying out otel (particularly
with development PHP settings, where trigger_error often breaks an application).
Adding a configuration value to control where logs go: OTEL_PHP_LOG_DESTINATION.

Author: brettmc

examples/global_providers.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+use OpenTelemetry\API\Globals;
+use OpenTelemetry\API\Instrumentation\Configurator;
+use OpenTelemetry\SDK\Trace\SpanExporter\ConsoleSpanExporterFactory;
+use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
+use OpenTelemetry\SDK\Trace\TracerProvider;
+
+require __DIR__ . '/../vendor/autoload.php';
+
+/**
+ * Example of globally registering <Signal>Provider instances.
+ * Generally this is hidden inside the SDK builder or SDK autoloading,
+ * but you can also do it manually. The providers are stored in
+ * context, and reset to previous values or defaults when the
+ * scope is detached.
+ */
+
+//before, a no-op provider is provided by default
+echo 'Before: ' . get_class(Globals::tracerProvider()) . PHP_EOL;
+
+$tracerProvider = TracerProvider::builder()->addSpanProcessor(
+    new SimpleSpanProcessor(
+        (new ConsoleSpanExporterFactory())->create()
+    )
+)->build();
+
+$configurator = Configurator::create()
+    ->withTracerProvider($tracerProvider);
+
+$scope = $configurator->activate();
+//activated, now our $tracerProvider is globally available
+echo 'During: ' . get_class(Globals::tracerProvider()) . PHP_EOL;
+
+$scope->detach();
+
+//after scope detached, back to default no-op providers:
+echo 'After: ' . get_class(Globals::tracerProvider()) . PHP_EOL;

examples/logs/exporters/otlp_grpc.php

@@ -4,9 +4,6 @@
 
 namespace OpenTelemetry\Example;
 
-use Monolog\Handler\StreamHandler;
-use Monolog\Logger;
-use OpenTelemetry\API\LoggerHolder;
 use OpenTelemetry\API\Logs\EventLogger;
 use OpenTelemetry\API\Logs\LogRecord;
 use OpenTelemetry\API\Signals;
@@ -19,14 +16,9 @@
 use OpenTelemetry\SDK\Logs\LoggerProvider;
 use OpenTelemetry\SDK\Logs\LogRecordLimitsBuilder;
 use OpenTelemetry\SDK\Logs\Processor\BatchLogRecordProcessor;
-use Psr\Log\LogLevel;
 
 require __DIR__ . '/../../../vendor/autoload.php';
 
-LoggerHolder::set(
-    new Logger('otel-php', [new StreamHandler(STDOUT, LogLevel::DEBUG)])
-);
-
 $transport = (new GrpcTransportFactory())->create('http://collector:4317' . OtlpUtil::method(Signals::LOGS));
 $exporter = new LogsExporter($transport);
 $loggerProvider = new LoggerProvider(

examples/logs/exporters/otlp_http.php

@@ -4,9 +4,6 @@
 
 namespace OpenTelemetry\Example;
 
-use Monolog\Handler\StreamHandler;
-use Monolog\Logger;
-use OpenTelemetry\API\LoggerHolder;
 use OpenTelemetry\API\Logs\EventLogger;
 use OpenTelemetry\API\Logs\LogRecord;
 use OpenTelemetry\Contrib\Otlp\LogsExporter;
@@ -16,14 +13,9 @@
 use OpenTelemetry\SDK\Logs\LoggerProvider;
 use OpenTelemetry\SDK\Logs\LogRecordLimitsBuilder;
 use OpenTelemetry\SDK\Logs\Processor\SimpleLogRecordProcessor;
-use Psr\Log\LogLevel;
 
 require __DIR__ . '/../../../vendor/autoload.php';
 
-LoggerHolder::set(
-    new Logger('otel-php', [new StreamHandler(STDOUT, LogLevel::DEBUG)])
-);
-
 $transport = (new OtlpHttpTransportFactory())->create('http://collector:4318/v1/logs', 'application/json');
 $exporter = new LogsExporter($transport);
 

examples/metrics/exporters/otlp_grpc.php

@@ -13,8 +13,6 @@
 use OpenTelemetry\SDK\Common\Time\ClockFactory;
 use OpenTelemetry\SDK\Metrics\MetricReader\ExportingReader;
 
-\OpenTelemetry\API\LoggerHolder::set(new \Monolog\Logger('grpc', [new \Monolog\Handler\StreamHandler('php://stderr')]));
-
 $clock = ClockFactory::getDefault();
 
 $reader = new ExportingReader(

examples/sdk_builder.php

@@ -2,10 +2,7 @@
 
 declare(strict_types=1);
 
-use Monolog\Handler\StreamHandler;
-use Monolog\Logger;
 use OpenTelemetry\API\Instrumentation\CachedInstrumentation;
-use OpenTelemetry\API\LoggerHolder;
 use OpenTelemetry\API\Trace\Propagation\TraceContextPropagator;
 use OpenTelemetry\Contrib\Otlp\MetricExporter;
 use OpenTelemetry\SDK\Common\Export\Http\PsrTransportFactory;
@@ -25,8 +22,6 @@
 
 echo 'Starting SDK builder example' . PHP_EOL;
 
-LoggerHolder::set(new Logger('grpc', [new StreamHandler('php://stderr')]));
-
 $resource = ResourceInfoFactory::defaultResource();
 $spanExporter = new InMemoryExporter();
 $logRecordExporter = new \OpenTelemetry\SDK\Logs\Exporter\InMemoryExporter();

examples/traces/exporters/otlp_file.php

@@ -6,18 +6,13 @@
 
 require __DIR__ . '/../../../vendor/autoload.php';
 
-use Monolog\Handler\StreamHandler;
-use Monolog\Logger;
-use OpenTelemetry\API\LoggerHolder;
 use OpenTelemetry\Contrib\Otlp\ContentTypes;
 use OpenTelemetry\Contrib\Otlp\SpanExporter;
 use OpenTelemetry\SDK\Common\Export\Stream\StreamTransportFactory;
 use OpenTelemetry\SDK\Common\Time\ClockFactory;
 use OpenTelemetry\SDK\Trace\SpanProcessor\BatchSpanProcessor;
 use OpenTelemetry\SDK\Trace\TracerProvider;
 
-LoggerHolder::set(new Logger('otlp-example', [new StreamHandler('php://stderr')]));
-
 $filename = sys_get_temp_dir() . '/traces.jsonl';
 $file = fopen($filename, 'a');
 $transport = (new StreamTransportFactory())->create($file, ContentTypes::NDJSON);

examples/traces/exporters/otlp_grpc.php

@@ -13,8 +13,6 @@
 use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
 use OpenTelemetry\SDK\Trace\TracerProvider;
 
-\OpenTelemetry\API\LoggerHolder::set(new \Monolog\Logger('grpc', [new \Monolog\Handler\StreamHandler('php://stderr')]));
-
 $transport = (new GrpcTransportFactory())->create('http://collector:4317' . OtlpUtil::method(Signals::TRACE));
 $exporter = new SpanExporter($transport);
 echo 'Starting OTLP GRPC example';

examples/traces/exporters/otlp_grpc_from_factory.php

@@ -8,8 +8,6 @@
 
 require __DIR__ . '/../../../vendor/autoload.php';
 
-\OpenTelemetry\API\LoggerHolder::set(new \Monolog\Logger('grpc', [new \Monolog\Handler\StreamHandler('php://stderr')]));
-
 /**
  * Create an otlp+grpc tracer provider from TracerProviderFactory, using environment variables as input
  */

examples/traces/exporters/otlp_http.php

@@ -6,16 +6,11 @@
 
 require __DIR__ . '/../../../vendor/autoload.php';
 
-use Monolog\Handler\StreamHandler;
-use Monolog\Logger;
-use OpenTelemetry\API\LoggerHolder;
 use OpenTelemetry\Contrib\Otlp\OtlpHttpTransportFactory;
 use OpenTelemetry\Contrib\Otlp\SpanExporter;
 use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
 use OpenTelemetry\SDK\Trace\TracerProvider;
 
-LoggerHolder::set(new Logger('otlp-example', [new StreamHandler('php://stderr')]));
-
 $transport = (new OtlpHttpTransportFactory())->create('http://collector:4318/v1/traces', 'application/x-protobuf');
 $exporter = new SpanExporter($transport);
 

examples/traces/exporters/otlp_http_from_factory.php

@@ -6,8 +6,6 @@
 
 require __DIR__ . '/../../../vendor/autoload.php';
 
-\OpenTelemetry\API\LoggerHolder::set(new \Monolog\Logger('grpc', [new \Monolog\Handler\StreamHandler('php://stderr')]));
-
 /**
  * Create an otlp+http/protobuf tracer provider from TracerProviderFactory, using environment variables as input
  */