Capture sources

The Extractor can run four source families at once. SQL Server and PostgreSQL observations exclude row values, and HTTP observations exclude request and response bodies. Capture output can still contain query strings, identifiers, names, and explicitly allowlisted OpenTelemetry attribute values. See Why Prologue for the complete boundary.

SQL Server

Enabled by	Adding an entry to prologue.sqlServer[]
Mechanism	Change Data Capture. The Extractor enables CDC on the database itself — no manual setup needed unless you set enableChangeDataCapture: false
Captures	Which tables and columns changed, per transaction
Never captures	Row values
Config	name, connectionString, enableChangeDataCapture, tables (allowlist), pollIntervalMilliseconds — see Configuration

PostgreSQL

Enabled by	Adding an entry to prologue.postgres[]
Mechanism	Logical replication. The Extractor creates its own replication slot and publication on the configured database — the server just needs wal_level = logical
Captures	Which tables and columns changed, per transaction
Never captures	Row values
Config	name, connectionString, slot, publication — see Configuration

HTTP

Enabled by	Adding a reverseProxy section — the Extractor becomes a YARP reverse proxy in front of your system
Mechanism	Every request that reaches the proxy passes through to your system unchanged; state-changing requests are also captured
Captures	Method, path including query string, response status, and the W3C traceparent trace id if present, for POST, PUT, and DELETE requests only
Never captures	GET/read traffic, request or response bodies
Config	Plain YARP routes/clusters configuration — see Configuration

OpenTelemetry

Enabled by	prologue.openTelemetry.enabled: true
Mechanism	An OTLP proxy (HTTP and gRPC). Telemetry is captured, then forwarded on to upstream.http/upstream.grpc unchanged — or nowhere, if you leave both empty, making the Extractor a terminal collector
Captures	Span, metric, and log names and identifiers; every observed attribute key; values only for configured attributeKeys; service names matching serviceNames, or all services when empty
Never captures	Log bodies, metric measurements, or values for attributes not in attributeKeys
Config	enabled, serviceNames, attributeKeys, upstream.http, upstream.grpc — see Configuration

How they combine

Any source family can run alone. When several are enabled, the correlator uses the correlation window and trace identifiers where available to associate currently unclaimed observations. The association is provisional: database transactions do not carry trace identifiers in the current contract and therefore correlate with HTTP commands by time.

Next

• Configuration — every property, with defaults.
• How Prologue works — the correlation heuristic in depth.