{"record":{"id":"a4efc82503dd60fd","repo":"crowdsecurity/crowdsec","slug":"while-compiling-grok-s-expression-w","errorCode":null,"errorMessage":"while compiling grok's expression: %w","messagePattern":"while compiling grok's expression: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/parser/grok.go","lineNumber":70,"sourceCode":"\t} else if g.RegexpValue != \"\" {\n\t\tif strings.HasSuffix(g.RegexpValue, \"\\n\") {\n\t\t\tlogger.Debugf(\"Beware, pattern ends with \\\\n: %q\", g.RegexpValue)\n\t\t}\n\n\t\trg.RunTimeRegexp, err = pctx.Grok.Compile(g.RegexpValue)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"failed to compile grok %q: %v\", g.RegexpValue, err)\n\t\t}\n\n\t\tlogger.Tracef(\"%s regexp: %s\", g.RegexpValue, rg.RunTimeRegexp.String())\n\t}\n\n\t// if grok source is an expression\n\tif g.ExpValue != \"\" {\n\t\trg.RunTimeValue, err = expr.Compile(g.ExpValue,\n\t\t\texprhelpers.GetExprOptions(map[string]any{\"evt\": &pipeline.Event{}})...)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"while compiling grok's expression: %w\", err)\n\t\t}\n\t}\n\n\t/* load grok statics */\n\t// compile expr statics if present\n\tfor _, static := range g.Statics {\n\t\tcompiled, err := static.Compile()\n\t\tif err != nil {\n\t\t\treturn nil, err\n\t\t}\n\n\t\trg.RuntimeStatics = append(rg.RuntimeStatics, *compiled)\n\t}\n\n\treturn rg, nil\n}\n\nfunc (g *GrokPattern) Validate() error {","sourceCodeStart":52,"sourceCodeEnd":88,"githubUrl":"https://github.com/crowdsecurity/crowdsec/blob/909b5157986a2b2c2163300fdaef5ed01289f7d2/pkg/parser/grok.go#L52-L88","documentation":"A grok node may carry an expr-lang expression (ExpValue) evaluated at runtime. Compile invokes expr.Compile with the standard event options; a syntactically or semantically invalid expression is wrapped as 'while compiling grok's expression'.","triggerScenarios":"Compile() calls expr.Compile(g.ExpValue, ...) and the expression fails to parse/type-check — unknown variables, wrong syntax, invalid function calls.","commonSituations":"Custom parser config with a bad expression (typo in evt field, missing quotes around a string, using a function that doesn't exist in exprhelpers); copying an expression from a newer/older crowdsec version using removed helpers.","solutions":["Fix the expression syntax in the 'expression' field of the grok node; ensure it only references known helpers (evt.*, functions from pkg/exprhelpers).","Test the expression with `cscli hub test` against a sample line to see the compile error in context.","Check the expr-lang documentation and exprhelpers package for available functions and valid field paths.","Verify collection version compatibility if the expression came from a hub collection."],"exampleFix":"// before\ngrok:\n  expression: evt.Parsed.some_field ==\n// after\ngrok:\n  expression: evt.Parsed.some_field == 'bar'","handlingStrategy":"validation","validationCode":"opts := exprhelpers.GetExprOptions(map[string]any{\"evt\": &pipeline.Event{}})\n_, err := expr.Compile(expValue, opts...)\nif err != nil {\n    return fmt.Errorf(\"grok expression %q invalid: %w\", expValue, err)\n}","typeGuard":null,"tryCatchPattern":"if _, err := node.Compile(pctx); err != nil {\n    if strings.Contains(err.Error(), \"compiling grok's expression\") {\n        logger.Errorf(\"bad expr in grok expression; check syntax and helper names: %v\", err)\n    }\n    return err\n}","preventionTips":["Test expressions with `cscli hub test` on sample log lines before deploying.","Only use documented evt fields and exprhelpers functions in expressions.","Quote string literals in expr (single quotes), and check operator completeness.","Pin collection versions so expressions match the runtime's helper set."],"tags":["parser","expr","grok","crowdsec"],"backgroundTag":"invalid-regex-pattern","analyzedSha":"909b5157986a2b2c2163300fdaef5ed01289f7d2","analyzedAt":"2026-09-06T12:27:26.012Z","contentChangedAt":"2026-09-06T12:27:26.012Z","schemaVersion":2},"datasetVersion":"2026-09-14T00:17:10.932Z"}