feat(logs): config-driven log transformations and static values for golden log lines

[AmitsinghTanwar007]

Summary

• Config-driven log transformations: Field renaming and nested JSON construction for golden log lines via [log.transformations.incoming] and [log.transformations.outgoing] config sections. Dotted target paths (e.g. "api_details.url") create nested JSON objects. Gated behind log-transformations feature flag.
• Runtime static values (split by direction): [log.static_values.incoming] and [log.static_values.outgoing] inject separate key-value pairs into each golden log line. This allows different values for the same field — e.g. hostname = "euler-gateway" on incoming vs hostname = "connector-service" on outgoing. Overridable per-request via x-config-override header — no server restart needed.
• transformation_mode: Controls whether event transformations copy or replace the original source fields ("copy" default, "replace" removes originals).
• Deadlock fix: log_utils::Storage::record_value() calls tracing::warn! for reserved keys, which re-enters the subscriber while holding the span extensions write lock → deadlock. Fixed by filtering reserved keys before entering with_current_span_mut.

Config Format

# Static values — separate maps for incoming (gRPC handler) and outgoing (connector call) golden log lines
[log.static_values.incoming]
hostname = "euler-gateway"
schema_version = "V2"

[log.static_values.outgoing]
hostname = "connector-service"

# Log transformations (behind feature flag)
[log.transformations.incoming]
"connector" = "gateway"
"api_details.request_body" = "request_body"
"api_details.response_body" = "response_body"
"api_details.status_code" = "status_code"
"api_details.error" = "error_message"

[log.transformations.outgoing]
"api_details.url" = "request.url"
"api_details.method" = "request.method"
"api_details.request_headers" = "request.headers"
"api_details.request_body" = "request.body"
"api_details.response_body" = "response.body"
"api_details.response_headers" = "response.headers"
"api_details.status_code" = "response.status_code"
"api_details.error" = "response.error_message"
"api_details.latency" = "latency"

Test Plan

1. Build and run

cargo run --features "grpc-server/log-transformations" -p grpc-server

2. gRPC request (static values via header override)

grpcurl -plaintext \
  -import-path crates/types-traits/grpc-api-types/proto \
  -proto services.proto \
  -H "x-auth: body-key" \
  -H "x-connector: authorizedotnet" \
  -H "x-api-key: <REDACTED>" \
  -H "x-key1: <REDACTED>" \
  -H "x-merchant-id: test_merchant_001" \
  -H "x-request-id: req-test-123" \
  -H 'x-config-override: {"log":{"static_values":{"incoming":{"custom_hostname":"incoming-host"},"outgoing":{"custom_hostname":"outgoing-host","custom_key":"my-custom-value"}}}}' \
  -d '{
    "merchant_transaction_id": "test_123",
    "amount": {"minor_amount": 1000, "currency": "USD"},
    "payment_method": {
      "card": {
        "card_number": {"value": "4111111111111111"},
        "card_exp_month": {"value": "03"},
        "card_exp_year": {"value": "2030"},
        "card_cvc": {"value": "737"},
        "card_holder_name": {"value": "John Doe"}
      }
    },
    "capture_method": "AUTOMATIC",
    "address": {"billing_address": {}},
    "auth_type": "NO_THREE_DS",
    "return_url": "https://example.com/return",
    "merchant_request_id": "test_123"
  }' \
  localhost:8000 types.PaymentService/Authorize

3. Response

{
  "merchantTransactionId": "120087958932",
  "connectorTransactionId": "120087958932",
  "status": "CHARGED",
  "statusCode": 200,
  "networkTransactionId": "XUB15TGRX3P9358QTM7XAM4",
  "connectorResponse": {
    "additionalPaymentMethodData": {
      "card": {
        "paymentChecks": "eyJhdnNfcmVzdWx0X2NvZGUiOiJZIiwiZGVzY3JpcHRpb24iOiJUaGUgc3RyZWV0IGFkZHJlc3MgYW5kIHBvc3RhbCBjb2RlIG1hdGNoZWQuIn0="
      }
    }
  },
  "connectorReferenceId": "120087958932"
}

4. Outgoing golden log line

Shows api_details nested object from log transformations + custom_hostname/custom_key from outgoing static values:

{
  "message": "[EXECUTE_CONNECTOR_PROCESSING_STEP - EVENT] Outgoing Request completed",
  "level": "INFO",
  "tag": "OutgoingApi",
  "log_type": "api",
  "message_": "Golden Log Line (outgoing)",
  "custom_key": "my-custom-value",
  "custom_hostname": "outgoing-host",
  "latency": "2432",
  "gateway": "authorizedotnet",
  "api_details": {
    "url": "https://apitest.authorize.net/xml/v1/request.api",
    "method": "POST",
    "latency": "2432",
    "request_body": "{...}",
    "response_body": "{...}",
    "request_headers": "{...}",
    "response_headers": "{...}"
  }
}

5. Incoming golden log line

Shows connector field from incoming transformation + api_details nested object + incoming static values:

{
  "message": "[PAYMENT_AUTHORIZE - EVENT] Golden Log Line (incoming - response)",
  "level": "INFO",
  "message_": "Golden Log Line (incoming)",
  "connector": "authorizedotnet",
  "custom_hostname": "incoming-host",
  "api_details": {
    "request_body": "{...}",
    "response_body": "PaymentServiceAuthorizeResponse { ... }"
  }
}

Checks

• cargo check -p grpc-server (without feature flag) — passes
• cargo check --features "grpc-server/log-transformations" -p grpc-server — passes
• End-to-end test with live connector call — transformations and static values appear in both golden log lines

Golden log incoming

Golden log outgoing