Compass

A tool designed to guide developers in the right direction for identifying and resolving performance issues.

---

Architecture

flowchart LR
   Extension["PECL Extension (Rust)"] --> compass_php_function["compass_php_function (USDT)"]
   Extension --> compass_request_shutdown["compass_request_shutdown (USDT)"]

   compass_php_function --> eBPF[eBPF Program]
   compass_request_shutdown --> eBPF

   eBPF --> Events["Events (Ring Buffer)"]

   Events --> CLI["CLI (Go)"]
   Events --> Sidecar["Sidecar (Go)"]

   Sidecar --> Stdout
   Sidecar --> OpenTelemetry

Performance

Performance data can be found in Github Actions for this build.

Components

Directory	Description
bpftrace	bpftrace scripts for testing the extension and demonstrating how the probes can be utilised.
extension	PHP extension which implements USDT probes.
cli	Commandline interface that collects telemetry from USDT probes.
sidecar	Sidecar that collects telemetry from USDT probes and log to stdout.

CLI

Trace

Compass provides developers with 2 types of traces:

• Complete - All function calls.
• Aggregated - Functions executed within the same span are combined.

Below is a condensed example:

{
  "requestID": "55eefc9aa6008d539ef954aff41806a7",
  "startTime": 1726972907007464,
  "executionTime": 6054,
  "functionCalls": [
    {
      "name": "Symfony\\Component\\DependencyInjection\\Compiler\\Compiler::compile",
      "startTime": 1726972907128013,
      "endTime": 1726972907517795
    },
    {
      "name": "Symfony\\Component\\DependencyInjection\\ContainerBuilder::compile",
      "startTime": 1726972907128009,
      "endTime": 1726972907518593
    },
    {
      "name": "Drupal\\Core\\DrupalKernel::compileContainer",
      "startTime": 1726972907009684,
      "endTime": 1726972907518625
    },
    {
      "name": "Drupal\\Core\\DrupalKernel::initializeContainer",
      "startTime": 1726972907008223,
      "endTime": 1726972907612239
    },
    {
      "name": "Drupal\\Core\\DrupalKernel::boot",
      "startTime": 1726972907008040,
      "endTime": 1726972907612295
    },
  ],
}

Images

PHP Extension

ghcr.io/skpr/compass:extension-8.3-latest
ghcr.io/skpr/compass:extension-8.2-latest
ghcr.io/skpr/compass:extension-8.1-latest

Collector

ghcr.io/skpr/compass:collector-latest

Configuration

COMPONENT	ENVIRONMENT VARIABLE	DEFAULT VALUE	Description
Extension	COMPASS_ENABLED	false	Enable the Compass extension
Extension	COMPASS_MODE		What mode the extension should operate. Empty will collect all executions. Setting to "header" will only collect executions when a specific header is set (see COMPASS_HEADER).
Extension	COMPASS_HEADER		Used to lock down which executions are traced. Need to set X-Compass for requests and needs to match this config.
Extension	COMPASS_FUNCTION_THRESHOLD	10000	Watermark for which functions to trace.
CLI + Sidecar	COMPASS_PROCESS_NAME	php-fpm	Name of the process to trace.
CLI + Sidecar	COMPASS_EXTENSION_PATH	/usr/lib/php/modules/compass.so	Path to extension library which has probes.
Sidecar	COMPASS_SIDECAR_REQUEST_THRESHOLD	100	Watermark for which requests to trace.
Sidecar	COMPASS_SIDECAR_FUNCTION_THRESHOLD	10	Watermark for which functions to trace.
Sidecar	COMPASS_SIDECAR_LOG_LEVEL	info	Logging level for the collector component. Set to "debug" for debug notices.
Sidecar	COMPASS_SIDECAR_SINK	stdout	Choose which metrics sink to use.
Sidecar	COMPASS_SIDECAR_OTEL_ENDPOINT	http://jaeger:4318/v1/traces	Endpoint to send OpenTelemetry traces to.
Sidecar	COMPASS_SIDECAR_OTEL_SERVICE_NAME		Name of the service assign this trace to.