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Pulse

Pulse is an Application Performance Monitoring (APM) service that helps you understand and optimize your Rails application’s performance.

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Features

Request Tracing

Trace requests across your entire stack with distributed tracing

Performance Metrics

Track response times, throughput, and error rates

Database Insights

Identify slow queries and N+1 problems

Auto-Instrumentation

13 libraries automatically instrumented

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Quick Start

Add the gem and configure:
Gemfile
gem 'brainzlab'
config/initializers/brainzlab.rb
BrainzLab.configure do |config|
  config.secret_key = ENV['BRAINZLAB_SECRET_KEY']
  config.pulse_enabled = true
end
That’s it! Pulse automatically instruments your application.

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Automatic Instrumentation

Pulse automatically tracks these libraries:
LibraryWhat’s Tracked
Rails/RackRequests, responses, timing breakdown
Active RecordSQL queries with duration
Net::HTTPOutbound HTTP calls
FaradayHTTP client requests
HTTPartyHTTP client requests
RedisCommands and duration
SidekiqJobs, queue wait time, distributed tracing
Delayed::JobJob execution
GraphQLQuery and field resolution
GrapeAPI endpoints
MongoDBDatabase operations
ElasticsearchSearch operations
ActionMailerEmail delivery time

Instrumentation Details

See detailed documentation for each instrumented library

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Performance Insights

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Latency Percentiles

Track P50, P95, and P99 latencies to understand your performance distribution:
  • P50 - Median response time (50% of requests faster)
  • P95 - 95th percentile (only 5% slower)
  • P99 - 99th percentile (catches outliers)

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Throughput

Monitor requests per minute over time to:
  • Spot traffic patterns
  • Identify peak hours
  • Plan capacity

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Error Rate

Track error percentage across:
  • All endpoints
  • Individual routes
  • Background jobs

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Distributed Tracing

Pulse supports distributed tracing across services: 
Web Request (trace-123)
├── Rails Controller (50ms)
│   ├── SQL: SELECT users (5ms)
│   └── HTTP: api.stripe.com (30ms)
└── Sidekiq Job (linked via trace-123)
    ├── SQL: UPDATE orders (3ms)
    └── Redis: SET order:123 (1ms)
Supported propagation formats:
  • W3C Trace Context (traceparent header)
  • B3 (X-B3-TraceId, X-B3-SpanId headers)

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Custom Spans

Add custom spans for business logic: 
BrainzLab::Pulse.trace("calculate_shipping", kind: "business") do |span|
  span[:data] = {
    weight: package.weight,
    destination: address.country
  }

  ShippingCalculator.calculate(package, address)
end

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Dashboard

View your performance data in the Pulse dashboard:
  • Overview - Apdex score, latency, throughput, errors
  • Endpoints - Performance by route
  • Traces - Individual request waterfalls
  • Database - Slow queries, N+1 detection

View Dashboard

Open the Pulse dashboard

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Configuration

BrainzLab.configure do |config|
  # Enable/disable Pulse
  config.pulse_enabled = true

  # Sample rate (1.0 = 100%)
  config.pulse_sample_rate = 1.0

  # Exclude paths
  config.pulse_excluded_paths = ['/health', '/ping', '/assets']

  # Disable specific instrumentations
  config.instrument_redis = false
  config.instrument_sidekiq = false
end

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What’s Next?

SDK Setup

Detailed SDK configuration

Instrumentation

All supported libraries

Traces

Understanding trace data

Metrics

Custom metrics