Skip to content
Kong Logo | Kong Docs Logo
search
  • We're Hiring!
  • Docs
    • Kong Gateway
    • Kong Konnect
    • Kong Mesh
    • Plugin Hub
    • decK
    • Kubernetes Ingress Controller
    • Insomnia
    • Kuma

    • Docs contribution guidelines
  • Plugin Hub
  • Support
  • Community
  • Kong Academy
Get a Demo Start Free Trial
  • Kong Gateway
  • Kong Konnect
  • Kong Mesh
  • Plugin Hub
  • decK
  • Kubernetes Ingress Controller
  • Insomnia
  • Kuma

  • Docs contribution guidelines
  • 3.2.x (latest)
  • 3.1.x
  • 3.0.x
  • 2.8.x
  • 2.7.x
  • 2.6.x
  • Older Enterprise versions (2.1-2.5)
  • Older OSS versions (2.1-2.5)
  • Archive (pre-2.1)
    • Overview of Kong Gateway
      • Version Support Policy
      • Supported Installation Options
      • Supported Linux Distributions
    • Stability
    • Release Notes
      • Services
        • Overview
        • Configure Routes with Expressions
      • Upstreams
      • Plugins
      • Routing Traffic
      • Load Balancing
      • Health Checks and Circuit Breakers
      • Kong Performance Testing
    • Glossary
    • Get Kong
    • Services and Routes
    • Rate Limiting
    • Proxy Caching
    • Key Authentication
    • Load-Balancing
      • Overview
        • Overview
        • Deploy Kong Gateway in Hybrid mode
      • DB-less Deployment
      • Traditional
      • Overview
        • Helm
        • OpenShift with Helm
        • kubectl apply
        • Kubernetes Deployment Options
        • Using docker run
        • Build your own Docker images
        • Amazon Linux
        • Debian
        • Red Hat
        • Ubuntu
      • Running Kong as a non-root user
      • Securing the Admin API
      • Using systemd
      • Start Kong Gateway Securely
      • Programatically Creating Admins
      • Enabling RBAC
      • Overview
      • Download your License
      • Deploy Enterprise License
      • Using the License API
      • Monitor Licenses Usage
      • Default Ports
      • DNS Considerations
      • Network and Firewall
      • CP/DP Communication through a Forward Proxy
    • Kong Configuration File
    • Environment Variables
    • Serving a Website and APIs from Kong
      • Overview
      • Prometheus
      • StatsD
      • Datadog
      • Overview
      • Writing a Custom Trace Exporter
      • Tracing API Reference
    • Resource Sizing Guidelines
    • Security Update Process
    • Blue-Green Deployments
    • Canary Deployments
    • Clustering Reference
      • Log Reference
      • Dynamic log level updates
      • Customize Gateway Logs
      • Upgrade Kong Gateway 3.1.x
      • Migrate from OSS to Enterprise
    • Overview
      • Overview
      • Metrics
      • Analytics with InfluxDB
      • Analytics with Prometheus
      • Estimate Analytics Storage in PostgreSQL
      • Overview
      • Getting Started
      • Advanced Usage
        • Overview
        • Environment Variables
        • AWS Secrets Manager
        • Google Secrets Manager
        • Hashicorp Vault
        • Securing the Database with AWS Secrets Manager
      • Reference Format
      • Overview
      • Get Started with Dynamic Plugin Ordering
      • Overview
      • Enable the Dev Portal
      • Publish an OpenAPI Spec
      • Structure and File Types
      • Themes Files
      • Working with Templates
      • Using the Editor
        • Basic Auth
        • Key Auth
        • OIDC
        • Sessions
        • Adding Custom Registration Fields
        • Manage Developers
        • Developer Roles and Content Permissions
        • Authorization Provider Strategy
        • Enable Application Registration
        • Enable Key Authentication for Application Registration
          • External OAuth2 Support
          • Set up Okta and Kong for External Oauth
          • Set up Azure AD and Kong for External Authentication
        • Manage Applications
        • Theme Editing
        • Migrating Templates Between Workspaces
        • Markdown Rendering Module
        • Customizing Portal Emails
        • Adding and Using JavaScript Assets
        • Single Page App in Dev Portal
        • Alternate OpenAPI Renderer
      • SMTP
      • Workspaces
      • Helpers CLI
      • Portal API Documentation
    • Audit Logging
    • Keyring and Data Encryption
    • Workspaces
    • Consumer Groups
    • Event Hooks
    • FIPS 140-2
    • Overview
    • Enable Kong Manager
      • Services and Routes
      • Rate Limiting
      • Proxy Caching
      • Authentication with Consumers
      • Load Balancing
      • Overview
      • Create a Super Admin
      • Workspaces and Teams
      • Reset Passwords and RBAC Tokens
      • Basic Auth
        • Configure LDAP
        • LDAP Service Directory Mapping
        • Configure OIDC
        • OIDC Authenticated Group Mapping
      • Sessions
        • Overview
        • Enable RBAC
        • Add a Role and Permissions
        • Create a User
        • Create an Admin
    • Networking Configuration
    • Workspaces
    • Create Consumer Groups
    • Sending Email
    • Overview
    • File Structure
    • Implementing Custom Logic
    • Plugin Configuration
    • Accessing the Data Store
    • Storing Custom Entities
    • Caching Custom Entities
    • Extending the Admin API
    • Writing Tests
    • (un)Installing your Plugin
      • Overview
      • kong.client
      • kong.client.tls
      • kong.cluster
      • kong.ctx
      • kong.ip
      • kong.jwe
      • kong.log
      • kong.nginx
      • kong.node
      • kong.request
      • kong.response
      • kong.router
      • kong.service
      • kong.service.request
      • kong.service.response
      • kong.table
      • kong.tracing
      • kong.vault
      • kong.websocket.client
      • kong.websocket.upstream
      • Go
      • Javascript
      • Python
      • Running Plugins in Containers
      • External Plugin Performance
    • Overview
        • Overview
        • OpenID Connect with Curity
        • OpenID Connect with Azure AD
        • OpenID Connect with Google
        • OpenID Connect with Okta
        • OpenID Connect with Auth0
        • OpenID Connect with Cognito
      • Authentication Reference
      • Allow Multiple Authentication Plugins
    • Rate Limiting Plugin
      • Add a Body Value
    • GraphQL
      • gRPC Plugins
      • Configure a gRPC service
    • Overview
    • Information Routes
    • Health Routes
    • Tags
    • Debug Routes
    • Services
    • Routes
    • Consumers
    • Plugins
    • Certificates
    • CA Certificates
    • SNIs
    • Upstreams
    • Targets
    • Vaults
    • Keys
    • Licenses
    • Workspaces
    • RBAC
    • Admins
    • Developers
    • Consumer Groups
    • Event Hooks
    • Keyring and Data Encryption
    • Audit Logs
    • kong.conf
    • Injecting Nginx Directives
    • CLI
    • File Permissions Reference
    • Key Management
    • Performance Testing Framework
    • Router Expressions Language
    • FAQ

github-edit-pageEdit this page

report-issueReport an issue

enterprise-switcher-iconSwitch to OSS

On this page
  • Before you start
  • Create a tracer
    • Sampling traces
  • Create a span
  • Get or set the active span
    • Scope
  • Set the span attributes
  • Set the span events
    • Record error message
  • Set the span status
  • Release the span (optional)
  • Visualize the trace
  • References
Kong Gateway
3.1.x
  • Home
  • Kong Gateway
  • Production Deployment
  • Tracing
  • Tracing API Referenece
You are browsing documentation for an outdated version. See the latest documentation here.

Tracing API Referenece

Before you start

In Gateway version 3.0.0, the tracing API became part of the Kong core application. The API is in the kong.tracing namespace.

The tracing API follows the OpenTelemetry API specification. This specification defines how to use the API as an instrument to your module. If you are familiar with the OpenTelemetry API, the tracing API will be familiar.

With the tracing API, you can set the instrumentation of your module with the following operations:

  • Span
  • Attributes

Create a tracer

Kong uses a global tracer internally to instrument the core modules and plugins.

By default, the tracer is a NoopTracer. The tracer is first initialized when opentelemetry_tracing configuration is enabled.

You can create a new tracer manually, or use the global tracer instance:

local tracer

-- Create a new tracer
tracer = kong.tracing.new("custom-tracer")

-- Use the global tracer
tracer = kong.tracing

Sampling traces

The sampling rate of a tracer can be configured:

local tracer = kong.tracing.new("custom-tracer", {
  -- Set the sampling rate to 0.1
  sampling_rate = 0.1,
})

The default sampling rate is 1.0, which samples all traces.

Create a span

A span represents a single operation within a trace. Spans can be nested to form trace trees. Each trace contains a root span, which typically describes the entire operation and, optionally, one or more sub-spans for its sub-operations.

local tracer = kong.tracing

local span = tracer:start_span("my-span")

The span properties can be set by passing a table to the start_span method.

local span = tracer:start_span("my-span", {
  start_time_ns = ngx.now() * 1e9, -- override the start time
  span_kind = 2, -- SPAN_KIND
                  -- UNSPECIFIED: 0
                  -- INTERNAL: 1
                  -- SERVER: 2
                  -- CLIENT: 3
                  -- PRODUCER: 4
                  -- CONSUMER: 5
  should_sample = true, -- by setting it to `true` to ignore the sampling decision
})

Make sure to ends the span when you are done:

span:finish() -- ends the span

Note: The span table will be cleared and put into the table pool after the span is finished, do not use it after the span is finished.

Get or set the active span

The active span is the span that is currently being executed.

To avoid overheads, the active span is manually set by calling the set_active_span method. When you finish a span, the active span becomes the parent of the finished span.

To set or get the active span, you can use the following example code:

local tracer = kong.tracing
local span = tracer:start_span("my-span")
tracer.set_active_span(span)

local active_span = tracer.active_span() -- returns the active span

Scope

The tracers are scoped to a specific context by a namespace key.

To get the active span for a specific namespace, you can use the following:

-- get global tracer's active span, and set it as the parent of new created span
local global_tracer = kong.tracing
local tracer = kong.tracing.new("custom-tracer")

local root_span = global_tracer.active_span()
local span = tracer.start_span("my-span", {
  parent = root_span
})

Set the span attributes

The attributes of a span are a map of key-value pairs and can be set by passing a table to the set_attributes method.

local span = tracer:start_span("my-span")

The OpenTelemetry specification defines the general semantic attributes, it can be used to describe the span. It could also be meaningful to visualize the span in a UI.

span:set_attribute("key", "value")

The following semantic conventions for spans are defined:

  • General: General semantic attributes that may be used in describing different kinds of operations.
  • HTTP: For HTTP client and server spans.
  • Database: For SQL and NoSQL client call spans.
  • RPC/RMI: For remote procedure call (e.g., gRPC) spans.
  • Messaging: For messaging systems (queues, publish/subscribe, etc.) spans.
  • FaaS: For Function as a Service (e.g., AWS Lambda) spans.
  • Exceptions: For recording exceptions associated with a span.
  • Compatibility: For spans generated by compatibility components, e.g. OpenTracing Shim layer.

Set the span events

The events of a span are time-series events that can be set by passing a table to the add_event method.

local span = kong.tracing:start_span("my-span")
span:add_event("my-event", {
  -- attributes
  ["key"] = "value",
})

Record error message

The event could also be used to record error messages.

local span = kong.tracing:start_span("my-span")
span:record_error("my-error-message")

-- or (same as above)
span:add_event("exception", {
  ["exception.message"] = "my-error-message",
})

Set the span status

The status of a span is a status code and can be set by passing a table to the set_status method.

local span = kong.tracing:start_span("my-span")
-- Status codes:
-- - `0` unset
-- - `1` ok
-- - `2` error

Release the span (optional)

The spans are stored in a pool, and can be released by calling the release method.

local span = kong.tracing:start_span("my-span")
span:release()

By default, the span will be released after the Nginx request ends.

Visualize the trace

Because of the compatibility with OpenTelemetry, the traces can be natively visualized through any OpenTelemetry UI.

Please refer to the OpenTelemetry plugin to see how to visualize the traces.

References

  • Tracing PDK
  • OpenTelemetry plugin
Thank you for your feedback.
Was this page useful?
  • Kong
    THE CLOUD CONNECTIVITY COMPANY

    Kong powers reliable digital connections across APIs, hybrid and multi-cloud environments.

    • Company
    • Customers
    • Events
    • Investors
    • Careers Hiring!
    • Partners
    • Press
    • Contact
  • Products
    • Kong Konnect
    • Kong Gateway
    • Kong Mesh
    • Get Started
    • Pricing
  • Resources
    • eBooks
    • Webinars
    • Briefs
    • Blog
    • API Gateway
    • Microservices
  • Open Source
    • Install Kong Gateway
    • Kong Community
    • Kubernetes Ingress
    • Kuma
    • Insomnia
  • Solutions
    • Decentralize
    • Secure & Govern
    • Create a Dev Platform
    • API Gateway
    • Kubernetes
    • Service Mesh
Star
  • Terms•Privacy
© Kong Inc. 2023