From d41bde234a2d324dac41a8580b3e98094d196ff3 Mon Sep 17 00:00:00 2001 From: Mayo Date: Tue, 9 Aug 2022 03:56:14 +0800 Subject: [PATCH] Add tracing sections for gateway 3.0 (#4014) * add tracing * fix links * fix broken links * placeholder * copy edit * remove plugin development doc * move tracing to kong production Co-authored-by: angel --- app/_data/docs_nav_gateway_3.0.x.yml | 11 +- src/gateway/kong-production/tracing/api.md | 206 ++++++++++++++++++ src/gateway/kong-production/tracing/index.md | 40 ++++ .../tracing/write-custom-trace-exporter.md | 32 +++ 4 files changed, 288 insertions(+), 1 deletion(-) create mode 100644 src/gateway/kong-production/tracing/api.md create mode 100644 src/gateway/kong-production/tracing/index.md create mode 100644 src/gateway/kong-production/tracing/write-custom-trace-exporter.md diff --git a/app/_data/docs_nav_gateway_3.0.x.yml b/app/_data/docs_nav_gateway_3.0.x.yml index 63270299617c..894112bae4df 100644 --- a/app/_data/docs_nav_gateway_3.0.x.yml +++ b/app/_data/docs_nav_gateway_3.0.x.yml @@ -152,6 +152,14 @@ items: url: /kong-production/monitoring/prometheus - text: How to monitor with Statsd url: /kong-production/monitoring/statsd + - text: Tracing + items: + - text: Overview + url: /kong-production/tracing/ + - text: How to Write a Custom Trace Exporter + url: /kong-production/tracing/write-custom-trace-exporter + - text: Tracing API reference + url: /kong-production/tracing/api - text: Resource Sizing Guidelines url: /kong-production/sizing-guidelines - text: Kong security update process @@ -369,7 +377,7 @@ items: url: /plugin-development/tests - text: (un)Installing your plugin url: /plugin-development/distribution - - text: Plugin Developmen Kit + - text: Plugin Development Kit items: - text: Overview url: /plugin-development/pdk/ @@ -452,6 +460,7 @@ items: url: /kong-plugins/rate-limiting/algorithms/rate-limiting - text: Configuring Fixed bucket url: /kong-plugins/rate-limiting/algorithms/fixed-bucket + - text: GraphQL url: /kong-plugins/graphql-quickstart - text: gRPC diff --git a/src/gateway/kong-production/tracing/api.md b/src/gateway/kong-production/tracing/api.md new file mode 100644 index 000000000000..20d246c8b8e1 --- /dev/null +++ b/src/gateway/kong-production/tracing/api.md @@ -0,0 +1,206 @@ +--- +title: Tracing API Referenece +content-type: Reference +--- + +## 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](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/api.md). +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](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/api.md#span) +- [Attributes](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/span-general.md) + +## Create a tracer + +Kong uses a global tracer internally to instrument the core modules and plugins. + +By default, the tracer is a [NoopTracer](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/api.md#get-a-tracer). The tracer is first initialized when `opentelemetry_tracing` configuration is enabled. + +You can create a new tracer manually, or use the global tracer instance: + +```lua +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: + +```lua +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. + +```lua +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. + +```lua +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: + +```lua +span:finish() -- ends the span +``` + +{:.Note} +>**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: + +```lua +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: + +```lua +-- 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. + +```lua +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. + +```lua +span:set_attribute("key", "value") +``` + +The following semantic conventions for spans are defined: + +* [General](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/span-general.md): General semantic attributes that may be used in describing different kinds of operations. +* [HTTP](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md): For HTTP client and server spans. +* [Database](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/database.md): For SQL and NoSQL client call spans. +* [RPC/RMI](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/rpc.md): For remote procedure call (e.g., gRPC) spans. +* [Messaging](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/messaging.md): For messaging systems (queues, publish/subscribe, etc.) spans. +* [FaaS](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/faas.md): For [Function as a Service](https://en.wikipedia.org/wiki/Function_as_a_service) (e.g., AWS Lambda) spans. +* [Exceptions](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/exceptions.md): For recording exceptions associated with a span. +* [Compatibility](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/compatibility.md): 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. + +```lua +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. + +```lua +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. + +```lua +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. + +```lua +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](/hub/kong-inc/opentelemetry) to see how to visualize the traces. + +## References + +- [Tracing PDK](/gateway/{{page.kong_version}}/pdk/kong.tracing) +- [OpenTelemetry plugin](/hub/kong-inc/opentelemetry) diff --git a/src/gateway/kong-production/tracing/index.md b/src/gateway/kong-production/tracing/index.md new file mode 100644 index 000000000000..632de425cadf --- /dev/null +++ b/src/gateway/kong-production/tracing/index.md @@ -0,0 +1,40 @@ +--- +title: Tracing Reference +content-type: reference +--- + +In this section, we will describe the tracing capabilities of Kong. + +## Core instrumentations + +**Note** +Only works for the plugins that are built on top of Kong's tracing API. +e.g. OpenTelemetry plugin. + +Kong provides a set of core instrumentations for tracing, these can be configured in the `opentelemetry_tracing` configuration. + +- `off`: do not enable instrumentations. +- `request`: only enable request-level instrumentations. +- `all`: enable all the following instrumentations. +- `db_query`: trace database query, including PostgresSQL and Cassandra. +- `dns_query`: trace DNS query. +- `router`: trace router execution, including router rebuilding. +- `http_client`: trace OpenResty HTTP client requests. +- `balancer`: trace balancer retries. +- `plugin_rewrite`: trace plugins iterator execution with rewrite phase. +- `plugin_access`: trace plugins iterator execution with access phase. +- `plugin_header_filter`: trace plugins iterator execution with `header_filter` phase. + +## Propagation + +The tracing API support to propagate the following headers: +- `w3c` - [W3C trace context](https://www.w3.org/TR/trace-context/) +- `b3`, `b3-single` - [Zipkin headers](https://github.com/openzipkin/b3-propagation) +- `jaeger` - [Jaeger headers](https://www.jaegertracing.io/docs/client-libraries/#propagation-format) +- `ot` - [OpenTracing headers](https://github.com/opentracing/specification/blob/master/rfc/trace_identifiers.md) +- `datadog` - [Datadog headers](https://docs.datadoghq.com/tracing/agent/propagation/) + +The tracing API will detect the propagation format from the headers, and will use the appropriate format to propagate the span context. +If no appropriate format is found, then will fallback to the default format, which can be specified. + +The propagation api works for both the OpenTelemetry plugin and the Zipkin plugin. diff --git a/src/gateway/kong-production/tracing/write-custom-trace-exporter.md b/src/gateway/kong-production/tracing/write-custom-trace-exporter.md new file mode 100644 index 000000000000..8f5481692671 --- /dev/null +++ b/src/gateway/kong-production/tracing/write-custom-trace-exporter.md @@ -0,0 +1,32 @@ +--- +title: How to write a custom trace exporter +content-type: how-to +--- + +Kong bundled OpenTelemetry plugin in core with a implementation of [OTLP/HTTP](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/otlp.md#otlphttp), but you can still write your own exporter at scale. + + +## Gathering the spans + +The spans are stored in the tracer's buffer. +The buffer is a queue of spans that are awaiting to be sent to the backend. + +You can access the buffer and process the span using the `span_processor` function. + +```lua +-- Use the global tracer +local tracer = kong.tracing + +-- Process the span +local span_processor = function(span) + -- clone the span so it can be processed after the original one is cleared + local span_dup = table.clone(span) + -- you can transform the span, add tags, etc. to other specific data structures +end +``` + +The `span_processor` function should be called in the `log` phase of the plugin. + +## Full example + +Refer to [Github](https://github.com/Kong/kong/tree/master/spec/fixtures/custom_plugins/kong/plugins/tcp-trace-exporter) to see the example of a custom trace exporter.