Context Attributes

@arizeai/phoenix-otel re-exports the OpenInference context setters from @arizeai/openinference-core. These functions write values into the OpenTelemetry context so helper-created spans and many instrumented child spans can inherit them automatically.

Available setters:

setSession(context, { sessionId })
setUser(context, { userId })
setMetadata(context, metadataObject)
setTags(context, string[])
setPromptTemplate(context, { template, variables?, version? })
setAttributes(context, attributes)

npm install @arizeai/phoenix-otel

import {  context,  setAttributes,  setMetadata,  setPromptTemplate,  setSession,  setTags,  setUser,} from "@arizeai/phoenix-otel";let ctx = context.active();ctx = setSession(ctx, { sessionId: "sess-42" });ctx = setUser(ctx, { userId: "user-7" });ctx = setMetadata(ctx, { tenant: "acme", environment: "prod" });ctx = setTags(ctx, ["support", "priority-high"]);ctx = setPromptTemplate(ctx, {  template: "Answer using docs about {topic}",  variables: { topic: "billing" },  version: "v3",});ctx = setAttributes(ctx, { "app.request_id": "req-123" });await context.with(ctx, async () => {  await doTracedWork();});

How Context Propagation Works#

Each setter takes a Context and returns a new Context with the value attached. Activate that context with context.with(). Any span created inside the callback can then inherit the propagated attributes.

import { context, setSession } from "@arizeai/phoenix-otel";const ctx = setSession(context.active(), { sessionId: "sess-123" });await context.with(ctx, async () => {  await myTracedFunction();});

Setters compose by chaining because each one returns the updated context:

import {  context,  setMetadata,  setSession,  setTags,  setUser,} from "@arizeai/phoenix-otel";const ctx = setTags(  setMetadata(    setUser(      setSession(context.active(), { sessionId: "sess-123" }),      { userId: "user-456" }    ),    { environment: "production", version: "1.4.2" }  ),  ["premium", "beta-feature"]);await context.with(ctx, () => runPipeline());

API Reference#

`setSession(context, session)`#

Attaches a session ID. Spans receive the session.id attribute.

import { context, setSession } from "@arizeai/phoenix-otel";await context.with(  setSession(context.active(), { sessionId: "conv-abc-123" }),  () => handleConversation());

Parameter	Type	Description
`context`	`Context`	The current OpenTelemetry context.
`session`	`{ sessionId: string }`	The session identifier.

`setUser(context, user)`#

Attaches a user ID. Spans receive the user.id attribute.

import { context, setUser } from "@arizeai/phoenix-otel";await context.with(  setUser(context.active(), { userId: "user-456" }),  () => handleRequest());

Parameter	Type	Description
`context`	`Context`	The current OpenTelemetry context.
`user`	`{ userId: string }`	The user identifier.

`setMetadata(context, metadata)`#

Attaches arbitrary key-value metadata. Serialized as JSON on the metadata span attribute.

import { context, setMetadata } from "@arizeai/phoenix-otel";await context.with(  setMetadata(context.active(), {    environment: "production",    region: "us-east-1",    model: "gpt-4o",  }),  () => handleRequest());

Parameter	Type	Description
`context`	`Context`	The current OpenTelemetry context.
`metadata`	`Record<string, unknown>`	Key-value pairs to attach.

`setTags(context, tags)`#

Attaches a list of string tags.

import { context, setTags } from "@arizeai/phoenix-otel";await context.with(  setTags(context.active(), ["premium-user", "beta-feature", "high-priority"]),  () => handleRequest());

Parameter	Type	Description
`context`	`Context`	The current OpenTelemetry context.
`tags`	`string[]`	Tags to attach.

`setAttributes(context, attributes)`#

Attaches arbitrary span attributes. Unlike setMetadata, these become individual span attributes rather than a single serialized JSON blob.

import { context, setAttributes } from "@arizeai/phoenix-otel";await context.with(  setAttributes(context.active(), {    "deployment.environment": "staging",    "request.priority": 1,  }),  () => handleRequest());

Parameter	Type	Description
`context`	`Context`	The current OpenTelemetry context.
`attributes`	`Attributes`	Valid OpenTelemetry span attribute values.

`setPromptTemplate(context, promptTemplate)`#

Attaches a prompt template and its variable bindings.

import { context, setPromptTemplate } from "@arizeai/phoenix-otel";await context.with(  setPromptTemplate(context.active(), {    template: "Answer the user's question about {{topic}}: {{question}}",    variables: { topic: "billing", question: "How do I upgrade?" },    version: "v2.1",  }),  () => callLLM());

Parameter	Type	Description
`context`	`Context`	The current OpenTelemetry context.
`promptTemplate`	`{ template: string; variables?: Record<string, string>; version?: string }`	Template text, bound variables, and optional version.

Manual Span Propagation#

If you create spans manually with a plain OpenTelemetry tracer, copy the propagated attributes onto the span explicitly:

import {  context,  getAttributesFromContext,  trace,} from "@arizeai/phoenix-otel";const tracer = trace.getTracer("manual-tracer");const span = tracer.startSpan("manual-span");span.setAttributes(getAttributesFromContext(context.active()));span.end();

If you use OITracer instead of a plain tracer, it automatically merges context attributes during startSpan() and startActiveSpan().

Combining Multiple Setters#

Build up context incrementally when different parts of your code learn different pieces of request metadata:

import {  context,  register,  setMetadata,  setSession,  setUser,  traceAgent,  traceTool,} from "@arizeai/phoenix-otel";register({ projectName: "support-bot" });const searchKB = traceTool(  async (query: string) => [{ title: "Reset Guide" }],  { name: "search-kb" });const supportAgent = traceAgent(  async (question: string) => {    const docs = await searchKB(question);    return `Found ${docs.length} articles`;  },  { name: "support-agent" });async function handleRequest(userId: string, sessionId: string, question: string) {  const ctx = setMetadata(    setUser(      setSession(context.active(), { sessionId }),      { userId }    ),    { source: "web-chat" }  );  return context.with(ctx, () => supportAgent(question));}

Clearing Context Values#

Each setter has a matching clearer:

clearSession
clearUser
clearMetadata
clearTags
clearPromptTemplate
clearAttributes

import {  clearAttributes,  clearMetadata,  clearPromptTemplate,  clearSession,  clearTags,  clearUser,  context,  setMetadata,  setSession,} from "@arizeai/phoenix-otel";let ctx = setMetadata(  setSession(context.active(), { sessionId: "sess-123" }),  { environment: "prod" });ctx = clearMetadata(ctx);ctx = clearSession(ctx);ctx = clearUser(ctx);ctx = clearTags(ctx);ctx = clearPromptTemplate(ctx);ctx = clearAttributes(ctx);

Context Attributes

Relevant Source Files

How Context Propagation Works#

API Reference#

`setSession(context, session)`#

`setUser(context, user)`#

`setMetadata(context, metadata)`#

`setTags(context, tags)`#

`setAttributes(context, attributes)`#

`setPromptTemplate(context, promptTemplate)`#

Manual Span Propagation#

Combining Multiple Setters#

Clearing Context Values#

Source Map

Relevant Source Files

How Context Propagation Works#

API Reference#

setSession(context, session)#

setUser(context, user)#

setMetadata(context, metadata)#

setTags(context, tags)#

setAttributes(context, attributes)#

setPromptTemplate(context, promptTemplate)#

Manual Span Propagation#

Combining Multiple Setters#

Clearing Context Values#

Source Map

`setSession(context, session)`#

`setUser(context, user)`#

`setMetadata(context, metadata)`#

`setTags(context, tags)`#

`setAttributes(context, attributes)`#

`setPromptTemplate(context, promptTemplate)`#