Concept

In tracing (especially distributed tracing, such as in OpenTelemetry), the terms resource, scope, and span each represent specific concepts in how trace data is structured and organized:

🧱 Span — the basic unit of trace

• A span represents a single operation within a trace.
• It's the core unit in a trace and has:
  • A name (e.g., "HTTP GET /api/users")
  • A start and end timestamp
  • Attributes (key-value pairs)
  • Parent-child relationships (to form the hierarchy of a trace)
  • Optionally, events and status

📌 Example: A span could represent a function call, an HTTP request, or a DB query.

"span" : {
    "traceId" : "1cb33ab03e6864be0bde9716a49be89b",
    "spanId" : "78817076c9cd460b",
    "traceState" : "",
    "parentSpanId" : "6472d7eccbd5f820",
    "name" : "/hello",
    "kind" : "Server",
    "startTimeUnixNano" : 1747908105861,
    "endTimeUnixNano" : 1747908106545,
    "attributes" : {
        "baggage key:client" : "cli",
        "baggage key:method" : "repl",
        "http.flavor" : "1.1",
        "http.host" : "demo-server:7080",
        "http.method" : "GET",
        "http.scheme" : "http",
        "http.server_name" : "/hello",
        "http.status_code" : 200,
        "http.target" : "/hello",
        "http.user_agent" : "Go-http-client/1.1",
        "http.wrote_bytes" : 11,
        "net.host.name" : "demo-server",
        "net.host.port" : 7080,
        "net.peer.ip" : "192.168.97.6",
        "net.peer.port" : 34214,
        "net.transport" : "ip_tcp",
        "server-attribute" : "foo"
    },
}

🧭 Scope (a.k.a. Instrumentation Scope)

• A scope groups spans that are generated by the same instrumentation library.
• It helps identify which library (and version) created a span.
• Contains metadata like:
  • name (e.g., "io.opentelemetry.http")
  • version (e.g., "1.0.1")

📌 Example: All HTTP client spans created by opentelemetry-go v1.5.0 share the same scope.

"scope" : {
    "name" : "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp",
    "version" : "semver:0.37.0",
    "attributes" : { },
    "droppedAttributesCount" : 0
},

🧩 Resource

• A resource describes the entity producing telemetry data.
• It provides context about the service (or host) — like service name, host, environment, etc.
• Shared by all spans from the same producer.

🛠️ Common resource attributes:

• service.name (e.g., "user-service")
• host.name (e.g., "prod-server-123")
• cloud.provider, os.type, k8s.pod.name, etc.

📌 Example: A Kubernetes pod generating spans will have a resource with details about the pod, namespace, and node.

"resource" : {
    "attributes" : {
        "host.name" : "183ac322db40",
        "process.command_args" : [
            "/app/main"
        ],
        "process.executable.name" : "main",
        "process.executable.path" : "/app/main",
        "process.owner" : "root",
        "process.pid" : 1,
        "process.runtime.description" : "go version go1.18.10 linux/arm64",
        "process.runtime.name" : "go",
        "process.runtime.version" : "go1.18.10",
        "service.name" : "demo-server",
        "telemetry.sdk.language" : "go",
        "telemetry.sdk.name" : "opentelemetry",
        "telemetry.sdk.version" : "1.11.2"
    },
    "droppedAttributesCount" : 0
},

🧬 Trace Hierarchy Example:

Resource: { service.name="payment-service" }
 └── Scope: { name="otel-instrumentation-http", version="1.1.0" }
      └── Span: "HTTP GET /pay"
      └── Span: "Call to payment gateway"
 └── Scope: { name="otel-instrumentation-db", version="0.31.0" }
      └── Span: "SELECT * FROM transactions"