feat(gologshim): Add SetDefaultHandler#3418
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The migration to slog in #3364 broke go-log's ability to adjust subsystem log levels at runtime via SetLogLevel() and control output formatting (colors, json). This was a key debugging feature that allowed changing log verbosity without restarting daemons. This fix detects go-log's slog bridge via duck typing and uses it when available, restoring dynamic level control and unified formatting. When go-log isn't present, gologshim falls back to standalone slog handlers as before. The lazy handler pattern solves initialization order issues where package-level loggers are created before go-log's bridge is installed. Users just need to update to this version of go-libp2p and go-log with ipfs/go-log#176 - no code changes or init() hacks required. Prerequisite for addressing ipfs/kubo#11035
lidel
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Oct 27, 2025
gologshim/gologshim.go
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| // goLogBridge detects go-log's slog bridge via duck typing, without import dependency | ||
| type goLogBridge interface { | ||
| GoLogBridge() | ||
| } |
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ℹ️ this is the gist of the solution that avoids depending on go-log in go.mod
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Thanks lidel, I'll have a review by eod tomorrow. |
gammazero
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Oct 29, 2025
| return slog.New(&lazyBridgeHandler{ | ||
| system: system, | ||
| config: c, | ||
| }) |
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Yeah, cannot rely on init() order across multiple packages.
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gammazero
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temporary revert until regression in libp2p/go-libp2p#3418 is resolved
lidel
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temporary revert until regression in libp2p/go-libp2p#3418 is resolved
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temporary revert until regression described in libp2p/go-libp2p#3418 is resolved
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See #3419 |
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A small release that adjust some noisy logging levels and adds a method for dynamically change the slog Handler for better integration with applications that use go-log. ◆ lidel@lidel.org 3f09fa4 feat(gologshim): Add SetDefaultHandler (#3418) ◆ vsnqmzpw lidel@lidel.org 7b78dd6 fix(websocket): use debug level for http.Server errors
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go-libp2p v0.44+ uses slog instead of go-log, which breaks dynamic log level control via `lotus log set-level` for libp2p subsystems. Wire go-log's SlogHandler to both slog.SetDefault and gologshim to restore per-subsystem level control (dht, swarm2, bitswap, etc). Ref: ipfs/kubo#11039, libp2p/go-libp2p#3418
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go-libp2p v0.44+ uses slog instead of go-log, which breaks dynamic log level control via `lotus log set-level` for libp2p subsystems. Wire go-log's SlogHandler to both slog.SetDefault and gologshim to restore per-subsystem level control (dht, swarm2, bitswap, etc). Ref: ipfs/kubo#11039, libp2p/go-libp2p#3418
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Problem
The migration to slog in
broke go-log's ability to adjust subsystem log levels at runtime via
SetLogLevel() and control output formatting (colors, json). This was a key debugging feature that allowed changing log verbosity without restarting daemons.Things like
ipfs log tail,ipfs log leveland Diagnostic screen in ipfs-webui (ipfs/ipfs-webui#2392) are broken with go-libp2p 0.44 – no go-libp2p logs are available, users are unable to, for example adjustnatornet/identifytoDEBUGlevel at runtime to do diagnostics.Second problem was that logs that worked due to env-variable being set to DEBUG ignored the user-preferred formatting.
Long term we may want to move
go-logfromzapbackend toslog, but in the meantime we need to unblock software that uses it to be able to use go-libp2p without regressions.cc @MarcoPolo @gammazero for visibility
Solution
First of all, a lot of time went into restoring this. It was not easy to fix without introducing
go-logas a dependency.To avoid depending on
go-log, this PR detects go-log's slog bridge via duck typing and uses it when available, restoring dynamic level control and unified formatting. When go-log isn't present,gologshimfalls back to standalone slog handlers as before.The lazy handler pattern solves initialization order issues where package-level loggers are created before go-log's bridge is installed.The intention of this PR is to fix regression allowing existing software to update to latest go-libp2p.
With this approach, users that depend on both
go-logandgo-libp2pjust need to update to this version ofgo-libp2pandgo-logwith ipfs/go-log#176 -no code changes orinit()hacks required, and it does not matter in thish ordergo-logandgo-libp2pare imported and initialized by existing apps. Things "just work" without breaking existing userbase.Important
Original version of this PR was rejected by go-libp2p maintainers, and instead go-libp2p 0.45 requires go-log users to manually set up wiring. See https://github.com/ipfs/go-log/releases/tag/v2.9.0 and #3419 (comment)
Reference
ipfs log tailipfs/kubo#11035go-logandgo-libp2p