panurus

Driver Metrics

Overview

Panurus provides a shared metrics layer for all driver service implementations. Rather than each driver embedding its own instrumentation, a set of decorator wrappers in token/core/common/metrics/ transparently records Prometheus-style metrics around every driver service call. Both the FabToken and ZKAT-DLog drivers are wrapped identically, ensuring consistent observability regardless of the underlying token technology.

Approach

The metrics layer follows the Decorator Pattern: each wrapper implements the same driver.*Service interface as the real service, delegates every call to the inner implementation, and records three metrics per method invocation:

Metric type	What it captures
Counter (*_operations_total)	Total number of method invocations
Histogram (*_duration_seconds)	Execution duration of each call
Counter (*_errors_total)	Total number of calls that returned an error

All metrics carry four labels for multi-TMS filtering:

Label	Description
network	The Fabric network name
channel	The channel on which the TMS operates
namespace	The token namespace
method	The service method that was invoked (e.g., Issue, Transfer)

Wiring

During driver initialization, each driver factory wraps its concrete services before returning the TokenManagerService:

Caller  →  Metrics Wrapper  →  Concrete Driver Service
           (records metrics)    (business logic only)

This keeps business logic free of monitoring concerns and guarantees that any new driver automatically gets the same metrics by wrapping its services at construction time.

Wrapped Services

Five driver services are wrapped:

IssueService

Wraps driver.IssueService. Methods instrumented:

Method	Description
Issue	Create new tokens for one or more recipients
VerifyIssue	Validate an issue action against its output metadata
DeserializeIssueAction	Deserialize raw bytes into an IssueAction

Metrics emitted:

• issue_service_operations_total
• issue_service_duration_seconds
• issue_service_errors_total

TransferService

Wraps driver.TransferService. Methods instrumented:

Method	Description
Transfer	Move token ownership from sender to receiver(s)
VerifyTransfer	Validate a transfer action against its output metadata
DeserializeTransferAction	Deserialize raw bytes into a TransferAction

Metrics emitted:

• transfer_service_operations_total
• transfer_service_duration_seconds
• transfer_service_errors_total

AuditorService

Wraps driver.AuditorService. Methods instrumented:

Method	Description
AuditorCheck	Verify a token request and its metadata for regulatory compliance

Metrics emitted:

• auditor_service_operations_total
• auditor_service_duration_seconds
• auditor_service_errors_total

TokensService

Wraps driver.TokensService. Methods instrumented:

Method	Description
SupportedTokenFormats	Return the token formats the driver supports
Deobfuscate	Reveal the cleartext token from an opaque output and its metadata
Recipients	Extract the recipient identities from a token output

Metrics emitted:

• tokens_service_operations_total
• tokens_service_duration_seconds
• tokens_service_errors_total

TokensUpgradeService

Wraps driver.TokensUpgradeService. Methods instrumented:

Method	Description
NewUpgradeChallenge	Generate a random challenge for the upgrade protocol
GenUpgradeProof	Produce a zero-knowledge proof for a token upgrade
CheckUpgradeProof	Verify an upgrade proof against a challenge and tokens

Metrics emitted:

• tokens_upgrade_service_operations_total
• tokens_upgrade_service_duration_seconds
• tokens_upgrade_service_errors_total

Metric Reference

The full list of metrics emitted by the driver wrappers:

Metric Name	Type	Description
issue_service_operations_total	Counter	Total IssueService method invocations
issue_service_duration_seconds	Histogram	Duration of IssueService method calls
issue_service_errors_total	Counter	Total IssueService method errors
transfer_service_operations_total	Counter	Total TransferService method invocations
transfer_service_duration_seconds	Histogram	Duration of TransferService method calls
transfer_service_errors_total	Counter	Total TransferService method errors
auditor_service_operations_total	Counter	Total AuditorService method invocations
auditor_service_duration_seconds	Histogram	Duration of AuditorService method calls
auditor_service_errors_total	Counter	Total AuditorService method errors
tokens_service_operations_total	Counter	Total TokensService method invocations
tokens_service_duration_seconds	Histogram	Duration of TokensService method calls
tokens_service_errors_total	Counter	Total TokensService method errors
tokens_upgrade_service_operations_total	Counter	Total TokensUpgradeService method invocations
tokens_upgrade_service_duration_seconds	Histogram	Duration of TokensUpgradeService method calls
tokens_upgrade_service_errors_total	Counter	Total TokensUpgradeService method errors

All metrics use labels: network, channel, namespace, method.

Source

The wrapper implementations and their tests are located in:

• token/core/common/metrics/issue.go
• token/core/common/metrics/transfer.go
• token/core/common/metrics/auditor.go
• token/core/common/metrics/tokens.go
• token/core/common/metrics/upgrade.go
• token/core/common/metrics/wrappers_test.go

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