opentelemetry_nova

OpenTelemetry instrumentation for the Nova web framework.

Automatic HTTP request tracing and metrics following the OTel HTTP semantic conventions.

Installation

Add to your dependencies in rebar.config:

{deps, [
    {opentelemetry_nova, "~> 0.1"}
]}.

Setup

Call setup/0 during application startup:

opentelemetry_nova:setup().

Or with Prometheus export:

opentelemetry_nova:setup(#{prometheus => #{port => 9464}}).

Span Attributes

Server spans are created for every HTTP request with the following attributes:

Attribute	Source
http.request.method	Request method
http.response.status_code	Response status code
http.route	Matched route template (e.g. /users/:id)
url.path	Request path
url.scheme	http or https
server.address	Host header
server.port	Server port
client.address	X-Forwarded-For / Forwarded header, or peer IP
network.peer.address	Peer IP address
network.peer.port	Peer port
network.protocol.version	HTTP version (1.0, 1.1, 2, 3)
user_agent.original	User-Agent header
error.type	Status code as string on 5xx errors
nova.app	Nova application name
nova.controller	Controller module
nova.action	Action function

Span names follow the {METHOD} {route} convention (e.g. GET /users/:id).

Metrics

Metric	Type	Attributes
http.server.request.duration	Histogram (seconds)	method, scheme, host, port, status, route, error.type
http.server.active_requests	UpDown Counter	method, scheme, host, port
http.server.request.body.size	Histogram (bytes)	method, scheme, host, port, status, route, error.type
http.server.response.body.size	Histogram (bytes)	method, scheme, host, port, status, route, error.type

Components

• otel_nova_stream_h — Cowboy stream handler for HTTP tracing and metrics
• otel_nova_plugin — Nova plugin for span enrichment with route and controller info
• otel_nova_prom_exporter — Prometheus exporter with delta-to-cumulative conversion
• otel_nova_prom_server — HTTP server for Prometheus scraping

License

MIT