martin-helmich/prometheus-nginxlog-exporter

package relabeling

import (
    "path/filepath"
    "strings"
)

// Map maps a sourceValue from the access log line according to the relabeling
// config (matching against whitelists, regular expressions etc.)
func (r *Relabeling) Map(sourceValue string) (string, error) {
    if r.Split > 0 {
        separator := r.Separator
        if separator == "" {
            separator = " "
        }

        values := strings.Split(sourceValue, separator)

        if len(values) >= r.Split {
            sourceValue = values[r.Split-1]
        } else {
            sourceValue = ""
        }
    }

    if r.WhitelistExists {
        for pattern := range r.WhitelistMap {
            if strings.Contains(pattern, "*") {
                matched, err := filepath.Match(pattern, sourceValue)
                if err != nil {
                    return "other", nil // handle invalid pattern error if it occurs
                }
                if matched {
                    return sourceValue, nil
                }
            } else {
                if pattern == sourceValue {
                    return sourceValue, nil
                }
            }
        }

        return "other", nil
    }

    if len(r.Matches) > 0 {
        replacement := ""
        for i := range r.Matches {
            if r.Matches[i].CompiledRegexp.MatchString(sourceValue) {
                replacement = r.Matches[i].CompiledRegexp.ReplaceAllString(sourceValue, r.Matches[i].Replacement)
                break
            }
        }
        sourceValue = replacement
    }

    return sourceValue, nil
}