SCI Profiler PHP — Symfony

Guide to measuring the carbon footprint of a Symfony application with SCI Profiler PHP.

Use Cases and Functional Units

In Symfony every HTTP request handled by the kernel and every console command execution is a functional unit. The SCI score for GET /admin/products includes the entire Symfony lifecycle: kernel boot, event listeners, security firewall, controller invocation, Doctrine queries, Twig rendering, and response.

Typical use cases

Use Case	Functional Unit	What Happens Inside
Product listing page	`GET /products`	Kernel boot, router matching, security voter, controller, Doctrine DQL, Twig template, HTTP cache headers
API platform resource	`GET /api/products`	API Platform data provider, serialization, content negotiation, JSON-LD output
Form submission	`POST /contact`	CSRF token validation, form handling, Doctrine flush, event dispatch, redirect response
Admin panel (EasyAdmin)	`GET /admin/products`	EasyAdmin controller, Doctrine QueryBuilder, CRUD template rendering
Console command	`bin/console app:import-catalog`	Console kernel boot, service wiring, batch DB operations, progress output
Messenger worker	`bin/console messenger:consume async`	Worker loop, message deserialization, handler invocation, ack/reject
Webhook receiver	`POST /webhook/stripe`	Payload validation, signature verification, event handling, DB updates

What is NOT a functional unit in Symfony

NOT a Functional Unit	Why
`ProductRepository::findByCategory()`	Internal Doctrine repository method, part of a larger controller action
A single Doctrine DQL query	One step in serving a page, not the use case itself
`Twig::render('product/list.html.twig')`	Template rendering is one phase of the request, not the complete operation
An event listener execution	A hook in the kernel lifecycle, not a user intent
`MessageBusInterface::dispatch()`	Internal dispatch mechanism; the message handler processing is the real unit

Setup

Symfony local server

# Using phar:
php -d auto_prepend_file=/opt/sci-profiler.phar \
  -S 127.0.0.1:8000 -t public/
# Or using source:
# php -d auto_prepend_file=/opt/sci-profiler-php/src/bootstrap.php \
#   -S 127.0.0.1:8000 -t public/

Or if using the Symfony CLI:

# Create a php.ini override for the Symfony server
echo "auto_prepend_file=/opt/sci-profiler.phar" > php.ini.local
# Or with source: echo "auto_prepend_file=/opt/sci-profiler-php/src/bootstrap.php" > php.ini.local
symfony server:start --php-ini=php.ini.local

PHP-FPM (Nginx)

server {
    server_name staging.myapp.local;
    root /var/www/myapp/public;

    location ~ ^/index\.php(/|$) {
        # Using phar:
        fastcgi_param PHP_VALUE "auto_prepend_file=/opt/sci-profiler.phar";
        # Or using source:
        # fastcgi_param PHP_VALUE "auto_prepend_file=/opt/sci-profiler-php/src/bootstrap.php";
        fastcgi_pass unix:/run/php/php8.3-fpm.sock;
        fastcgi_split_path_info ^(.+\.php)(/.*)$;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        internal;
    }
}

Apache

<VirtualHost *:80>
    ServerName staging.myapp.local
    DocumentRoot /var/www/myapp/public

    # Using phar:
    php_value auto_prepend_file "/opt/sci-profiler.phar"
    # Or using source:
    # php_value auto_prepend_file "/opt/sci-profiler-php/src/bootstrap.php"

    <Directory /var/www/myapp/public>
        AllowOverride All
    </Directory>
</VirtualHost>

Docker

# Using phar:
COPY sci-profiler.phar /opt/sci-profiler.phar
RUN echo "auto_prepend_file=/opt/sci-profiler.phar" \
    >> /usr/local/etc/php/conf.d/sci-profiler.ini

# Or using source:
# COPY sci-profiler-php /opt/sci-profiler-php
# RUN echo "auto_prepend_file=/opt/sci-profiler-php/src/bootstrap.php" \
#     >> /usr/local/etc/php/conf.d/sci-profiler.ini

Console commands

# Using phar:
php -d auto_prepend_file=/opt/sci-profiler.phar \
  bin/console app:import-catalog --env=staging
# Or using source:
# php -d auto_prepend_file=/opt/sci-profiler-php/src/bootstrap.php \
#   bin/console app:import-catalog --env=staging

Messenger workers

# Using phar:
php -d auto_prepend_file=/opt/sci-profiler.phar \
  bin/console messenger:consume async --limit=100 --time-limit=300
# Or using source:
# php -d auto_prepend_file=/opt/sci-profiler-php/src/bootstrap.php \
#   bin/console messenger:consume async --limit=100 --time-limit=300

The profiler measures the entire worker process lifecycle. For per-message granularity, use --limit=1 or analyze the worker's total SCI divided by messages processed.

Configuration Example

<?php
// /opt/sci-profiler-php/config/sci-profiler.local.php
return [
    'enabled'               => true,
    'device_power_watts'    => 18.0,
    'grid_carbon_intensity' => 33.0,       // France (Ember Climate 2024)
    'output_dir'            => '/var/www/myapp/var/sci-profiler',
    'reporters'             => ['json', 'log', 'html'],
];

Or via environment (.env.staging):

SCI_PROFILER_ENABLED=1
SCI_PROFILER_DEVICE_POWER_WATTS=18
SCI_PROFILER_GRID_CARBON_INTENSITY=56
SCI_PROFILER_OUTPUT_DIR=%kernel.project_dir%/var/sci-profiler
SCI_PROFILER_REPORTERS=json,log,html

Note: %kernel.project_dir% is a Symfony parameter and is not resolved in plain environment variables. Use an absolute path or set it in the PHP config file instead.

Analyzing Routes

Group by Symfony route

Symfony URIs contain dynamic parameters. Normalize them for aggregation:

# Normalize IDs and UUIDs in URIs, then compute average SCI per route
cat /var/www/myapp/var/sci-profiler/sci-profiler.jsonl \
  | jq -r '{
      uri: (.["request.uri"]
        | split("?")[0]
        | gsub("/[0-9]+"; "/{id}")
        | gsub("/[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}"; "/{uuid}")),
      method: .["request.method"],
      sci: .["sci.sci_mgco2eq"],
      time: .["time.wall_time_ms"]
    }' \
  | jq -s '
    group_by(.method + " " + .uri)
    | map({
        route: (.[0].method + " " + .[0].uri),
        count: length,
        avg_sci_mgco2eq: (map(.sci) | add / length | . * 1000 | round / 1000),
        avg_time_ms: (map(.time) | add / length | round)
      })
    | sort_by(-.avg_sci_mgco2eq)
  '

API Platform endpoints vs Twig pages

cat /var/www/myapp/var/sci-profiler/sci-profiler.jsonl \
  | jq -s '
    group_by(.["request.uri"] | test("^/api/"))
    | map({
        type: (if .[0]["request.uri"] | test("^/api/") then "API Platform" else "Twig pages" end),
        requests: length,
        avg_sci: (map(.["sci.sci_mgco2eq"]) | add / length | . * 1000 | round / 1000),
        total_sci: (map(.["sci.sci_mgco2eq"]) | add | . * 1000 | round / 1000)
      })
  '

Console commands analysis

cat /var/www/myapp/var/sci-profiler/sci-profiler.jsonl \
  | jq 'select(.["request.method"] == "CLI")' \
  | jq -s '
    sort_by(-.["sci.sci_mgco2eq"])
    | map({
        command: .["request.uri"],
        sci_mgco2eq: .["sci.sci_mgco2eq"],
        time_ms: .["time.wall_time_ms"],
        peak_mb: .["memory.memory_peak_mb"]
      })
  '

Common Symfony Optimization Insights

Finding	Common Cause	Optimization
High SCI on first request after deploy	Symfony container not compiled, no warmed cache	Run `bin/console cache:warmup --env=prod` in deploy
Admin panel 5x frontend	EasyAdmin loading all CRUD metadata, unoptimized list queries	Add pagination limits, use custom DQL for heavy lists
API collection endpoints slow	API Platform fetching full entities with nested relations	Use DTO output classes, custom data providers with SELECT optimization
Messenger worker high total SCI	Worker bootstraps full container for each message batch	Tune `--limit` and `--time-limit`, use worker restart on deploy
Console imports dominate emissions	Processing all records in single pass	Use `doctrine:query` batching, `EntityManager::clear()` every N records
Twig rendering slow	Complex template inheritance with many includes	Use Twig cache (default in prod), simplify block hierarchy, use `render_esi` for heavy fragments
Event listeners add overhead	Doctrine lifecycle listeners firing on every flush	Use lazy listeners, limit `postFlush` logic, batch operations

Profiling with Symfony Profiler Side-by-Side

SCI Profiler PHP complements the Symfony Web Profiler. Use both together:

Symfony Profiler: shows detailed internal breakdown (Doctrine queries, Twig renders, event listeners, HTTP client calls)
SCI Profiler: shows the carbon cost of the same request

This combination lets you identify which internal operations drive the carbon cost of a route, and then use Symfony's tools to optimize them.

# Find the highest-SCI routes
cat /var/www/myapp/var/sci-profiler/sci-profiler.jsonl \
  | jq -s 'sort_by(-.["sci.sci_mgco2eq"]) | .[0:5] | map(.["request.uri"])' \

# Then inspect those routes in the Symfony Profiler at:
# http://staging.myapp.local/_profiler/

Carbon Budget in CI

# .github/workflows/sci-budget.yml
name: SCI Budget Check

on: [pull_request]

jobs:
  sci-check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Setup PHP
        uses: shivammathur/setup-php@v2
        with:
          php-version: '8.3'

      - name: Install dependencies
        run: composer install --no-interaction

      - name: Setup SCI Profiler
        run: |
          git clone https://github.com/fullo/sci-profiler-php.git /tmp/sci-profiler-php
          cd /tmp/sci-profiler-php && composer install --no-dev

      - name: Run functional tests with profiling
        run: |
          php -d auto_prepend_file=/tmp/sci-profiler-php/src/bootstrap.php \
            bin/phpunit --testsuite=functional
        env:
          SCI_PROFILER_ENABLED: 1
          SCI_PROFILER_OUTPUT_DIR: /tmp/sci-results
          SCI_PROFILER_REPORTERS: json

      - name: Check SCI budget
        run: |
          MAX_SCI=10.0
          VIOLATIONS=$(jq "select(.[\"sci.sci_mgco2eq\"] > $MAX_SCI)" \
            /tmp/sci-results/sci-profiler.jsonl | wc -l)
          if [ "$VIOLATIONS" -gt 0 ]; then
            echo "::error::$VIOLATIONS requests exceeded SCI budget of $MAX_SCI mgCO2eq"
            jq "select(.[\"sci.sci_mgco2eq\"] > $MAX_SCI) | [.\"request.method\", .\"request.uri\", .\"sci.sci_mgco2eq\"]" \
              /tmp/sci-results/sci-profiler.jsonl
            exit 1
          fi

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SCI Profiler PHP — Symfony

Use Cases and Functional Units

Typical use cases

What is NOT a functional unit in Symfony

Setup

Symfony local server

PHP-FPM (Nginx)

Apache

Docker

Console commands

Messenger workers

Configuration Example

Analyzing Routes

Group by Symfony route

API Platform endpoints vs Twig pages

Console commands analysis

Common Symfony Optimization Insights

Profiling with Symfony Profiler Side-by-Side

Carbon Budget in CI

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SCI Profiler PHP — Symfony

Use Cases and Functional Units

Typical use cases

What is NOT a functional unit in Symfony

Setup

Symfony local server

PHP-FPM (Nginx)

Apache

Docker

Console commands

Messenger workers

Configuration Example

Analyzing Routes

Group by Symfony route

API Platform endpoints vs Twig pages

Console commands analysis

Common Symfony Optimization Insights

Profiling with Symfony Profiler Side-by-Side

Carbon Budget in CI