golang-samber-oops

Persona: You are a Go engineer who treats errors as structured data. Every error carries enough context — domain, attributes, trace — for an on-call engineer to diagnose the problem without asking the developer. samber/oops Structured Error Handling samber/oops is a drop-in replacement for Go's standard error handling that adds structured context, stack traces, error codes, public messages, and panic recovery. Variable data goes in .With() attributes (not the message string), so APM tools (Datadog, Loki, Sentry) can group errors properly. Unlike the stdlib approach (adding slog attributes at the log site), oops attributes travel with the error through the call stack. Why use samber/oops Standard Go errors lack context — you see connection failed but not which user triggered it, what query was running, or the full call stack. samber/oops provides: Structured context — key-value attributes on any error Stack traces — automatic call stack capture Error codes — machine-readable identifiers Public messages — user-safe messages separate from technical details Low-cardinality messages — variable data in .With() attributes, not the message string, so APM tools group errors properly This skill is not exhaustive. Please refer to library documentation and code examples for more information. Context7 can help as a discoverability platform. Core pattern: Error builder chain All oops errors use a fluent builder pattern: err := oops . In ( "user-service" ) . // domain/feature Tags ( "database" , "postgres" ) . // categorization Code ( "network_failure" ) . // machine-readable identifier User ( "user-123" , "email" , "foo@bar.com" ) . // user context With ( "query" , query ) . // custom attributes Errorf ( "failed to fetch user: %s" , "timeout" ) Terminal methods: .Errorf(format, args...) — create a new error .Wrap(err) — wrap an existing error .Wrapf(err, format, args...) — wrap with a message .Join(err1, err2, ...) — combine multiple errors .Recover(fn) / .Recoverf(fn, format, args...) — convert panic to error Error builder methods Methods Use case .With("key", value) Add custom key-value attribute (lazy func() any values supported) .WithContext(ctx, "key1", "key2") Extract values from Go context into attributes (lazy values supported) .In("domain") Set the feature/service/domain .Tags("auth", "sql") Add categorization tags (query with err.HasTag("tag") ) .Code("iam_authz_missing_permission") Set machine-readable error identifier/slug .Public("Could not fetch user.") Set user-safe message (separate from technical details) .Hint("Runbook: https://doc.acme.org/doc/abcd.md") Add debugging hint for developers .Owner("team/slack") Identify responsible team/owner .User(id, "k", "v") Add user identifier and attributes .Tenant(id, "k", "v") Add tenant/organization context and attributes .Trace(id) Add trace / correlation ID (default: ULID) .Span(id) Add span ID representing a unit of work/operation (default: ULID) .Time(t) Override error timestamp (default: time.Now() ) .Since(t) Set duration based on time since t (exposed via err.Duration() ) .Duration(d) Set explicit error duration .Request(req, includeBody) Attach http.Request (optionally including body) .Response(res, includeBody) Attach http.Response (optionally including body) oops.FromContext(ctx) Start from an OopsErrorBuilder stored in a Go context Common scenarios Database/repository layer func ( r * UserRepository ) FetchUser ( id string ) ( * User , error ) { query := "SELECT * FROM users WHERE id = $1" row , err := r . db . Query ( query , id ) if err != nil { return nil , oops . In ( "user-repository" ) . Tags ( "database" , "postgres" ) . With ( "query" , query ) . With ( "user_id" , id ) . Wrapf ( err , "failed to fetch user from database" ) } // ... } HTTP handler layer func ( h * Handler ) CreateUser ( w http . ResponseWriter , r * http . Request ) { userID := getUserID ( r ) err := h . service . CreateUser ( r . Context ( ) , userID ) if err != nil { return oops . In ( "http-handler" ) . Tags ( "endpoint" , "/users" ) . Request ( r , false ) . User ( userID ) . Wrapf ( err , "create user failed" ) } w . WriteHeader ( http . StatusCreated ) } Service layer with reusable builder func ( s * UserService ) CreateOrder ( ctx context . Context , req CreateOrderRequest ) error { builder := oops . In ( "order-service" ) . Tags ( "orders" , "checkout" ) . Tenant ( req . TenantID , "plan" , req . Plan ) . User ( req . UserID , "email" , req . UserEmail ) product , err := s . catalog . GetProduct ( ctx , req . ProductID ) if err != nil { return builder . With ( "product_id" , req . ProductID ) . Wrapf ( err , "product lookup failed" ) } if product . Stock < req . Quantity { return builder . Code ( "insufficient_stock" ) . Public ( "Not enough items in stock." ) . With ( "requested" , req . Quantity ) . With ( "available" , product . Stock ) . Errorf ( "insufficient stock for product %s" , req . ProductID ) } return nil } Error wrapping best practices DO: Wrap directly, no nil check needed // ✓ Good — Wrap returns nil if err is nil return oops . Wrapf ( err , "operation failed" ) // ✗ Bad — unnecessary nil check if err != nil { return oops . Wrapf ( err , "operation failed" ) } return nil DO: Add context at each layer Each architectural layer SHOULD add context via Wrap/Wrapf — at least once per package boundary (not necessarily at every function call). // ✓ Good — each layer adds relevant context func Controller ( ) error { return oops . In ( "controller" ) . Trace ( traceID ) . Wrapf ( Service ( ) , "user request failed" ) } func Service ( ) error { return oops . In ( "service" ) . With ( "op" , "create_user" ) . Wrapf ( Repository ( ) , "db operation failed" ) } func Repository ( ) error { return oops . In ( "repository" ) . Tags ( "database" , "postgres" ) . Errorf ( "connection timeout" ) } DO: Keep error messages low-cardinality Error messages MUST be low-cardinality for APM aggregation. Interpolating variable data into the message breaks grouping in Datadog, Loki, Sentry. // ✗ Bad — high-cardinality, breaks APM grouping oops . Errorf ( "failed to process user %s in tenant %s" , userID , tenantID ) // ✓ Good — static message + structured attributes oops . With ( "user_id" , userID ) . With ( "tenant_id" , tenantID ) . Errorf ( "failed to process user" ) Panic recovery oops.Recover() MUST be used in goroutine boundaries. Convert panics to structured errors: func ProcessData ( data string ) ( err error ) { return oops . In ( "data-processor" ) . Code ( "panic_recovered" ) . Hint ( "Check input data format and dependencies" ) . With ( "panic_value" , r ) . Recover ( func ( ) { riskyOperation ( data ) } ) } Accessing error information samber/oops errors implement the standard error interface. Access additional info: if oopsErr , ok := err . ( oops . OopsError ) ; ok { fmt . Println ( "Code:" , oopsErr . Code ( ) ) fmt . Println ( "Domain:" , oopsErr . Domain ( ) ) fmt . Println ( "Tags:" , oopsErr . Tags ( ) ) fmt . Println ( "Context:" , oopsErr . Context ( ) ) fmt . Println ( "Stacktrace:" , oopsErr . Stacktrace ( ) ) } // Get public-facing message with fallback publicMsg := oops . GetPublic ( err , "Something went wrong" ) Output formats fmt . Printf ( "%+v\n" , err ) // verbose with stack trace bytes , _ := json . Marshal ( err ) // JSON for logging slog . Error ( err . Error ( ) , slog . Any ( "error" , err ) ) // slog integration Context propagation Carry error context through Go contexts: func middleware ( next http . Handler ) http . Handler { return http . HandlerFunc ( func ( w http . ResponseWriter , r * http . Request ) { builder := oops . In ( "http" ) . Request ( r , false ) . Trace ( r . Header . Get ( "X-Trace-ID" ) ) ctx := oops . WithBuilder ( r . Context ( ) , builder ) next . ServeHTTP ( w , r . WithContext ( ctx ) ) } ) } func handler ( ctx context . Context ) error { return oops . FromContext ( ctx ) . Tags ( "handler" , "users" ) . Errorf ( "something failed" ) } For assertions, configuration, and additional logger examples, see Advanced patterns . References github.com/samber/oops pkg.go.dev/github.com/samber/oops Cross-References → See samber/cc-skills-golang@golang-error-handling skill for general error handling patterns → See samber/cc-skills-golang@golang-observability skill for logger integration and structured logging