django-devbar 0.1.2

Lightweight performance devbar for Django

django-devbar

Lightweight performance devbar for Django. Shows DB query count, query duration, application time, and detects duplicate queries with visual severity indicators.

Installation

pip install django-devbar

Add to your middleware as early as possible, but after any middleware that encodes the response (e.g., GZipMiddleware):

MIDDLEWARE = [
    "django.middleware.security.SecurityMiddleware",
    "django_devbar.DevBarMiddleware",
    # ...
]

Configuration

# Position: bottom-right, bottom-left, top-right, top-left (default: bottom-right)
DEVBAR_POSITION = "top-left"

# Show HTML overlay (default: DEBUG)
DEVBAR_SHOW_BAR = True

# Add DevBar-* response headers (default: False)
DEVBAR_SHOW_HEADERS = True

# Enable console logging for duplicate queries (default: True)
DEVBAR_ENABLE_CONSOLE = True

# Performance thresholds for warning/critical levels (defaults shown)
DEVBAR_THRESHOLDS = {
    "time_warning": 500,    # ms
    "time_critical": 1500,  # ms
    "count_warning": 20,    # queries
    "count_critical": 50,   # queries
}

Response Headers

When DEVBAR_SHOW_HEADERS = True, performance metrics are added as HTTP response headers. This is useful for:

• API endpoints where the HTML overlay can't be displayed
• Automated testing to assert performance thresholds (e.g., fail CI if query count exceeds a limit)
• Monitoring tools that can capture and aggregate header values

Headers included:

Header	Example	Description
DevBar-Query-Count	12	Number of database queries executed
DevBar-DB-Time	87ms	Total time spent in database queries
DevBar-App-Time	41ms	Application time (total time minus DB time)
DevBar-Duplicates	3	Number of duplicate queries detected (only present if duplicates found)