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OpenTelemetry for Lua scripts (nauthilus_opentelemetry)

This module allows Lua scripts to create and control OpenTelemetry spans, set attributes/events/status, use baggage, and inject/extract trace headers. The module is request‑scoped and becomes a no‑op when tracing is disabled in configuration.

Controlled by server.insights.tracing.enabled. When disabled, the module functions are present but do nothing.

Loading​

local otel = require("nauthilus_opentelemetry")

Feature detection​

if not otel.is_enabled() then
  -- tracing disabled; skip expensive telemetry work
end

Creating spans​

local tr = otel.tracer("nauthilus/policy")

-- Start/End manually
local sp = tr:start_span("operation", { kind = "internal", attributes = { ["peer.service"] = "example" } })
sp:add_event("started")
sp:end()

-- With convenience: with_span
tr:with_span("policy.evaluate", function(span)
  span:set_attributes({ ["key"] = "value", ["tries"] = 1, ["ok"] = true })
end, { kind = "client" })

Span methods​

  • set_attribute(key, value) — value can be string/number/boolean
  • set_attributes(table) — bulk set attributes from a { key = value } table
  • add_event(name, attributes?)
  • set_status(code, description?) — code: ok | error | unset
  • record_error(err_or_msg) — marks span as error and records the error
  • end()

Options for start_span/with_span​

  • kind: internal (default) | client | server | producer | consumer
  • attributes: table of attributes { [string] = string|number|boolean }
  • links: array of { trace_id = "...", span_id = "...", attributes = { ... } }

Baggage​

otel.baggage_set("user.id", "42")
local v = otel.baggage_get("user.id")
for k, val in pairs(otel.baggage_all()) do print(k, val) end
otel.baggage_clear()

Header propagation (HTTP)​

local headers = { }
otel.inject_headers(headers)   -- write trace headers into table
-- ... perform HTTP request using these headers ...

-- Extract example (restore context from headers)
otel.extract_headers(headers)

Semantic convenience helpers​

local sem = otel.semconv
local attrs = sem.http_client_attrs({ method = "GET", url = "https://api.example.com", status_code = 200 })
-- Merge into span attributes
tr:with_span("http.call", function(span)
  span:set_attributes(attrs)
end, { kind = "client" })

Notes​

  • The module follows the active request span created by the server; child spans created in Lua will be attached to the current request’s context.
  • Attribute tables ignore unsupported value types to keep encoding stable.
  • See also: Guides → Tracing (OpenTelemetry) for server‑side configuration.