For more information, please consult the documentation of the main OpenTelemetry PHP project.
Issues have been disabled for this repo in order to help maintain consistency between this repo and the main OpenTelemetry PHP project repo. If you have an issue you'd like to raise about this issue, please use the OpenTelemetry PHP Issue section. Please prefix the title of the issue with [opentelemetry-php-instrumentation].
This is a PHP extension for OpenTelemetry, to enable auto-instrumentation. It is based on zend_observer and requires php8+
The extension allows:
- creating
pre
andpost
hook functions to arbitrary PHP functions and methods, which allows those methods to be wrapped with telemetry - adding attributes to functions and methods to enable observers at runtime
In PHP 8.2+, internal/built-in PHP functions can also be observed.
- PHP 8+
- OpenTelemetry PHP library
The extension can be installed in all of the usual ways:
pecl install opentelemetry
If you are using the official PHP docker images then you can use php-extension-installer
From github:
install-php-extensions opentelemetry-php/ext-opentelemetry@main
Via pecl/pickle:
install-php-extensions opentelemetry[-beta|-stable|-latest]
Pre-built windows binaries are available from the releases page
See https://wiki.php.net/internals/windows/stepbystepbuild_sdk_2#building_pecl_extensions_with_phpize for generic advice on building from source under Windows.
php --ri opentelemetry
The extension can be configured to not run if a conflicting extension is installed. The following extensions are known to not work when installed alongside OpenTelemetry:
- SourceGuardian
If the conflicting extension is a regular PHP extension (i.e, not a
zend_extension), you can control
conflicts via the opentelemetry.conflicts
ini setting.
If a conflicting extension is found, then the OpenTelemetry extension will disable itself:
php --ri opentelemetry
Notice: PHP Startup: Conflicting extension found (blackfire), disabling OpenTelemetry in Unknown on line 0
opentelemetry
opentelemetry hooks => disabled (conflict)
extension version => 1.0.0beta6
Directive => Local Value => Master Value
opentelemetry.conflicts => blackfire => blackfire
opentelemetry.validate_hook_functions => On => On
Invalid argument types in pre
and post
callbacks can cause fatal errors. Runtime checking is performed on the
hook functions to ensure they are compatible. If not, the hook will not be executed and an error will be generated.
This feature can be disabled by setting the opentelemetry.validate_hook_functions
ini value to Off
;
By default, increasing the number of arguments provided to a function in the pre hook is allowed only if that does not require the stack frame of the function call to be extended in size. For internal functions, adding arguments not provided at the callsite always requires stack extension. For PHP functions, it is required only if the argument is not included in the function definition.
Extending stack frame automatically can be enabled by setting opentelemetry.allow_stack_extension
ini value to On
.
This enables extending the stack frame by up to another 16 arguments.
The pre
method starts and activates a span. The post
method ends the span after the observed method has finished.
<?php
$tracer = new Tracer(...);
OpenTelemetry\Instrumentation\hook(
DemoClass::class,
'run',
pre: static function (DemoClass $demo, array $params, string $class, string $function, ?string $filename, ?int $lineno) use ($tracer) {
$span = $tracer->spanBuilder($class)
->startSpan();
Context::storage()->attach($span->storeInContext(Context::getCurrent()));
},
post: static function (DemoClass $demo, array $params, $returnValue, ?Throwable $exception) use ($tracer) {
$scope = Context::storage()->scope();
$scope?->detach();
$span = Span::fromContext($scope->context());
$exception && $span->recordException($exception);
$span->setStatus($exception ? StatusCode::STATUS_ERROR : StatusCode::STATUS_OK);
$span->end();
}
);
There are more examples in the tests directory
Note that if hooking a static class method, the first parameter to pre
and post
callbacks is a string
containing the method's class name.
- Be aware that trivial functions are candidates for optimizations. Optimizer can optimize them out and replace user function call with more optimal set of instructions (inlining). In this case hooks will not be invoked as there will be no function.
- Hooks must be registered before a function is first executed. You may encounter race conditions where the composer autoloader runs code that uses functions you wish to hook prior to the hooks being registered.
From a pre
hook function, you may modify the parameters before they are received by the observed function.
The arguments are passed in as a numerically-indexed array. The returned array from the pre
hook is used
to modify (not replace) the existing parameters:
<?php
OpenTelemetry\Instrumentation\hook(
null,
'hello',
function($obj, array $params) {
return [
0 => null, //make first param null
2 => 'baz', //replace 3rd param
3 => 'bat', //add 4th param
];
}
);
function hello($one = null, $two = null, $three = null, $four = null) {
var_dump(func_get_args());
}
hello('a', 'b', 'c');
gives output:
array(4) {
[0]=>
NULL
[1]=>
string(1) "b"
[2]=>
string(3) "baz"
[3]=>
string(3) "bat"
}
post
hook methods can modify the observed function's return value:
<?php
\OpenTelemetry\Instrumentation\hook(null, 'hello', post: fn(mixed $object, array $params, string $return): int => ++$return);
function hello(int $val) {
return $val;
}
var_dump(hello(1));
gives output:
int(2)
Important: the post method must provide a return type-hint, otherwise the return value will be ignored. The return type
hint in the example above is : int
.
post
hook methods can modify an exception thrown from the observed function:
<?php
\OpenTelemetry\Instrumentation\hook(null, 'hello', post: function(mixed $object, array $params, mixed $return, ?Throwable $throwable) {
throw new Exception('new', previous: $throwable);
});
function hello() {
throw new Exception('original');
}
try {
hello();
} catch (\Throwable $t) {
var_dump($t->getMessage());
var_dump($t->getPrevious()?->getMessage());
}
gives output:
string(3) "new"
string(8) "original"
By applying attributes to source code, the OpenTelemetry extension can add hooks at runtime.
Default pre and post hook methods are provided by the OpenTelemetry API: OpenTelemetry\API\Instrumentation\Handler::pre
and ::post
.
This feature is disabled by default, but can be enabled by setting opentelemetry.attr_hooks_enabled = On
in php.ini
Attribute-based hooks can only be applied to a function/method that does not already have hooks applied. Only one hook can be applied to a function/method, including via interfaces.
Since the attributes are evaluated at runtime, the extension checks whether a hook already exists to decide whether it should apply a new runtime hook.
This feature can be configured via .ini
by modifying the following entries:
opentelemetry.attr_hooks_enabled
- boolean, default Offopentelemetry.attr_pre_handler_function
- FQN of pre method/functionopentelemetry.attr_post_handler_function
- FQN of post method/function
This attribute is provided by the OpenTelemetry API can be applied to a function or class method.
You can also provide optional parameters to the attribute, which control:
- span name
- span kind
- attributes
use OpenTelemetry\API\Instrumentation\WithSpan
class MyClass
{
#[WithSpan]
public function trace_me(): void
{
/* ... */
}
#[WithSpan('custom_span_name', SpanKind::KIND_INTERNAL, ['my-attr' => 'value'])]
public function trace_me_with_customization(): void
{
/* ... */
}
}
#[WithSpan]
function my_function(): void
{
/* ... */
}
This attribute should be used in conjunction with WithSpan
. It is applied to function/method
parameters, and causes those parameters and values to be passed through to the pre
hook function
where they can be added as trace attributes.
There is one optional parameter, which controls the attribute key. If not set, the parameter name
is used.
use OpenTelemetry\API\Instrumentation\WithSpan
use OpenTelemetry\API\Instrumentation\SpanAttribute
class MyClass
{
#[WithSpan]
public function add_user(
#[SpanAttribute] string $username,
string $password,
#[SpanAttribute('a_better_attribute_name')] string $foo_bar_baz,
): void
{
/* ... */
}
See DEVELOPMENT.md and https://github.com/open-telemetry/opentelemetry-php/blob/main/CONTRIBUTING.md