cardano-node: remove iohk-monitoring tracing backend by jutaro · Pull Request #6580 · IntersectMBO/cardano-node

jutaro · 2026-05-26T11:29:28Z

Summary

Removes the legacy iohk-monitoring-based tracing infrastructure from
cardano-node, leaving trace-dispatcher as the sole tracing backend.

trace-dispatcher has been the production default since node 8.x. The old
iohk-monitoring path was retained during a transition period but is no longer
used or tested in production deployments. Removing it eliminates ~11 000 lines
of dead code and 9 transitive build dependencies.

What changed

Deleted (~8 100 lines, 15 modules):

All of Cardano.Tracing.* — Config, HasIssuer, Metrics, Render,
Shutdown, Startup, Tracers, and all OrphanInstances.* modules
(Byron, Common, Consensus, HardFork, Network, Shelley)
Cardano.Node.Configuration.Logging — the iohk-monitoring init layer
Cardano.Node.Tracing.Compat — compatibility shim

Modified:

Cardano.Node.Run — simplified to use only initTraceDispatcher; all
legacy createLoggingLayer / setupTrace / Cardano.BM.* imports gone
Cardano.Node.TraceConstraints — removes HasIssuer, ToObject, and
related iohk-monitoring constraints
cardano-node.cabal — drops iohk-monitoring, lobemo-backend-*,
lobemo-scribe-systemd, ekg-wai, tracer-transformers, scientific
Nix service config — removes legacy logging-layer options
Benchmark profiles — "tracing_backend" updated to "trace-dispatcher"

Breaking change

Any node config still using "UseTraceDispatcher": false or legacy
Logging config keys will need to be migrated to trace-dispatcher
configuration before upgrading. Refer to the trace-dispatcher migration guide.

Config options removed with iohk-monitoring

The following node configuration keys have no effect after the removal of the
iohk-monitoring tracing backend. All tracing is now handled exclusively by
trace-dispatcher.

Parsed by the node but silently ignored

These three keys are still accepted by the JSON parser to avoid hard failures
on existing configs, but have no effect:

Key	Previous effect
`TurnOnLogging`	Master on/off switch for the iohk-monitoring logging layer
`TurnOnLogMetrics`	Enabled/disabled node metrics collection via iohk-monitoring
`UseTraceDispatcher`	Chose between legacy (`false`) and trace-dispatcher (`true`) backend

Parsed by `Cardano.Tracing.Config` (module deleted)

Key	Previous effect
`TracingVerbosity`	Rendering verbosity: `MinimalVerbosity` / `NormalVerbosity` / `MaximalVerbosity`
`TraceAcceptPolicy`	Per-tracer on/off toggle (bool)
`TraceBackingStore`	"
`TraceBlockFetchClient`	"
`TraceBlockFetchDecisions`	"
`TraceBlockFetchProtocol`	"
`TraceBlockFetchProtocolSerialised`	"
`TraceBlockFetchServer`	"
`TraceBlockchainTime`	"
`TraceChainDB` / `TraceChainDb`	"
`TraceChainSyncClient`	"
`TraceChainSyncBlockServer`	"
`TraceChainSyncHeaderServer`	"
`TraceChainSyncProtocol`	"
`TraceChurnMode`	"
`TraceConnectionManager`	"
`TraceConnectionManagerCounters`	"
`TraceConnectionManagerTransitions`	"
`TraceCsj`	"
`TraceDevotedBlockFetch`	"
`TraceDiffusionInitialization`	"
`TraceDNS` / `TraceDnsResolver` / `TraceDnsSubscription`	"
`TraceErrorPolicy` / `TraceLocalErrorPolicy`	"
`TraceForge` / `TraceForgeStateInfo`	"
`TraceGDD`	"
`TraceGsm`	"
`TraceHandshake` / `TraceLocalHandshake`	"
`TraceInboundGovernor`	"
`TraceInboundGovernorCounters`	"
`TraceInboundGovernorTransitions`	"
`TraceIpSubscription`	"
`TraceKeepAliveClient` / `TraceKeepAliveProtocol`	"
`TraceKesAgent`	"
`TraceLedgerPeers`	"
`TraceLocalChainSyncProtocol`	"
`TraceLocalConnectionManager`	"
`TraceLocalMux` / `TraceLocalMuxBearer` / `TraceLocalMuxChannel`	"
`TraceLocalRootPeers`	"
`TraceLocalServer`	"
`TraceLocalStateQueryProtocol`	"
`TraceLocalTxMonitorProtocol`	"
`TraceLocalTxSubmissionProtocol` / `TraceLocalTxSubmissionServer`	"
`TraceMempool`	"
`TraceMux` / `TraceMuxBearer` / `TraceMuxChannel`	"
`TracePeerSelection` / `TracePeerSelectionActions` / `TracePeerSelectionCounters`	"
`TracePeerSharingProtocol`	"
`TracePublicRootPeers`	"
`TraceSanityCheckIssue`	"
`TraceServer`	"
`TraceTxCounters`	"
`TraceTxInbound` / `TraceTxOutbound`	"
`TraceTxLogic`	"
`TraceTxSubmissionProtocol` / `TraceTxSubmission2Protocol`	"

Read directly by the `iohk-monitoring` library

These keys were consumed by Cardano.BM.Configuration — the node never parsed
them itself. They are now entirely ignored:

Key	Previous effect
`minSeverity`	Global severity filter (`Debug` / `Info` / `Notice` / `Warning` / `Error` / `Critical`)
`rotation`	Log file rotation (`rpLogLimitBytes`, `rpKeepFilesNum`, `rpMaxAgeHours`)
`setupBackends`	Which backends to initialise (`KatipBK`, `EKGViewBK`, etc.)
`defaultBackends`	Default backend routing for namespaces
`setupScribes`	Log output targets (file, stdout, journald, trace-forwarder)
`defaultScribes`	Default scribe routing
`hasEKG`	Port for EKG web metrics interface
`hasPrometheus`	Host/port for Prometheus metrics endpoint
`options.mapBackends`	Per-namespace backend routing overrides
`options.mapSubtrace`	Per-namespace subtrace behaviour overrides
`options.mapSeverity`	Per-namespace severity filter overrides

Replacements in trace-dispatcher

The trace-dispatcher backend has its own equivalents for severity filtering
and output routing, configured under TraceOptions in the trace-dispatcher
config file. Refer to the trace-dispatcher documentation for the current config
format.

jutaro · 2026-05-26T11:47:28Z

The change in [Byron.hs:122] is:

Before:
( "txid" .= txId tx )
which relied on instance ToJSON (TxId (GenTx ByronBlock)) from the now-deleted Cardano.Tracing.OrphanInstances.Byron, which was:

instance ToJSON (TxId (GenTx ByronBlock)) where
toJSON = String . Text.take 8 . renderTxId
After:

( "txid" .= (Text.take 8 . renderTxId $ txId tx) )
The output is identical — both produce an 8-character hex string. The change just inlines the behavior that used to live in the deleted orphan instance, because that instance no longer exists.

Addresses all review comments from PR #6580 (mgmeier). The root cause of most issues was that `Cardano.Tracing.HasIssuer` was incorrectly deleted as part of the iohk-monitoring cleanup

config parsing Replace locally-defined orphan `ToJSON`/`FromJSON` instances that already exist in `Cardano.Network.OrphanInstances` (from the `cardano-diffusion:orphan-instances` sublibrary) with imports of that module: - `TopologyP2P`: remove `FromJSON/ToJSON PeerTrustable`, `FromJSON/ToJSON (NetworkTopology UseBootstrapPeers PeerTrustable)`, and `FromJSON UseBootstrapPeers`; add `Cardano.Network.OrphanInstances ()` and `Ouroboros.Network.OrphanInstances ()` imports. - `StateRep`: remove local `ToJSON/FromJSON NodeToNodeVersion`, `ToJSON/FromJSON NodeToClientVersion`, and `parseBoundedEnum`; add `Cardano.Network.OrphanInstances ()` import. - `Tracers`: remove Show-based `ToJSON NodeToNodeVersionData` and `ToJSON NodeToClientVersionData` stubs; add `Cardano.Network.OrphanInstances ()` import. Additionally fix two pre-existing issues in `Consensus.hs`: - `deltaq`: use `toJSON gsv` (structured JSON via `Ouroboros.Network.OrphanInstances`) instead of `String . show`. - `TraceDecisionEvent`: restore the `dtal >= DMaximum` conditional branch (replacing the reversed fold), using `forMachine DMaximum` for the verbose case. In `Startup.hs`, fix `ConsensusNetworkVersionTuple` to emit proper structured JSON for `nodeToClientVersion`/`nodeToNodeVersion` via `ToJSON` from `Cardano.Network.OrphanInstances`, and fix the `maxNodeToNode/ClientVersion` field to show only the version key rather than the full `(key, value)` pair.

…legacy tracing

mgmeier

Voila, finally, the great moment is upon us.
LGTM!

…nings

carbolymer · 2026-06-02T19:39:47Z

                , ("TestDijkstraHardForkAtEpoch", Aeson.Number 0)
                ]
                )
-  -- | Various tracers we can turn on or off


How does one configure tracing now? What are the defaults?

For example, I was using snippet below to enable PrometheusSimple endpoint - how do I do it now?

The trace-dispatcher backend has its own equivalents for severity filtering
and output routing, configured under TraceOptions in the trace-dispatcher
config file. Refer to the trace-dispatcher documentation for the current config
format.

Few more words how to configure tracing now w/ links would be greatly appreciated.

mgmeier requested changes May 26, 2026

View reviewed changes

jutaro added a commit that referenced this pull request May 27, 2026

Review fixes

2bcfdf9

Addresses all review comments from PR #6580 (mgmeier). The root cause of most issues was that `Cardano.Tracing.HasIssuer` was incorrectly deleted as part of the iohk-monitoring cleanup

mgmeier requested changes May 27, 2026

View reviewed changes

Comment thread cardano-node/src/Cardano/Node/Tracing/StateRep.hs

Comment thread cardano-node/src/Cardano/Node/Configuration/TopologyP2P.hs

jutaro marked this pull request as ready for review May 29, 2026 09:00

jutaro requested review from a team as code owners May 29, 2026 09:00

mgmeier force-pushed the remove-iohk-monitoring branch 2 times, most recently from bbeb171 to 54b60dd Compare June 2, 2026 14:18

mgmeier and others added 6 commits June 2, 2026 17:11

Remove iohk-monitoring-framework from project

01788ce

cardano-node: remove logging switch

742346a

cardano-testnet: adjust golden_DefaultConfig test case to removal of …

8fb0015

…legacy tracing

nix: remove legacy tracing artifacts

1a8a878

cardano-profile: remove oldtracing profiles

a046f30

mgmeier force-pushed the remove-iohk-monitoring branch from 54b60dd to 606f5bb Compare June 2, 2026 15:11

mgmeier added the DO NOT MERGE label Jun 2, 2026

mgmeier approved these changes Jun 2, 2026

View reviewed changes

wb: stop supervisord from spamming stderr with python deprecation war…

ed26482

…nings

mgmeier force-pushed the remove-iohk-monitoring branch from 606f5bb to ed26482 Compare June 2, 2026 15:36

f-f mentioned this pull request Jun 2, 2026

Release v11.1.0 #6588

Open

carbolymer reviewed Jun 2, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

cardano-node: remove iohk-monitoring tracing backend#6580

cardano-node: remove iohk-monitoring tracing backend#6580
jutaro wants to merge 7 commits into
masterfrom
remove-iohk-monitoring

jutaro commented May 26, 2026 •

edited by mgmeier

Loading

Uh oh!

jutaro commented May 26, 2026

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

mgmeier left a comment •

edited

Loading

Uh oh!

carbolymer Jun 2, 2026 •

edited

Loading

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

Conversation

jutaro commented May 26, 2026 • edited by mgmeier Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

What changed

Breaking change

Config options removed with iohk-monitoring

Parsed by the node but silently ignored

Parsed by Cardano.Tracing.Config (module deleted)

Read directly by the iohk-monitoring library

Replacements in trace-dispatcher

Uh oh!

jutaro commented May 26, 2026

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

mgmeier left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

carbolymer Jun 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

jutaro commented May 26, 2026 •

edited by mgmeier

Loading

Parsed by `Cardano.Tracing.Config` (module deleted)

Read directly by the `iohk-monitoring` library

mgmeier left a comment •

edited

Loading

carbolymer Jun 2, 2026 •

edited

Loading