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// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package logging
import (
"net/http"
"strings"
"go.uber.org/zap"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
)
func init() {
caddy.RegisterModule(LogAppend{})
}
// LogAppend implements a middleware that takes a key and value, where
// the key is the name of a log field and the value is a placeholder,
// or variable key, or constant value to use for that field.
type LogAppend struct {
// Key is the name of the log field.
Key string `json:"key,omitempty"`
// Value is the value to use for the log field.
// If it is a placeholder (with surrounding `{}`),
// it will be evaluated when the log is written.
// If the value is a key that exists in the `vars`
// map, the value of that key will be used. Otherwise
// the value will be used as-is as a constant string.
Value string `json:"value,omitempty"`
}
// CaddyModule returns the Caddy module information.
func (LogAppend) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.log_append",
New: func() caddy.Module { return new(LogAppend) },
}
}
func (h LogAppend) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
// Run the next handler in the chain first.
// If an error occurs, we still want to add
// any extra log fields that we can, so we
// hold onto the error and return it later.
handlerErr := next.ServeHTTP(w, r)
// On the way back up the chain, add the extra log field
ctx := r.Context()
vars := ctx.Value(caddyhttp.VarsCtxKey).(map[string]any)
repl := ctx.Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
extra := ctx.Value(caddyhttp.ExtraLogFieldsCtxKey).(*caddyhttp.ExtraLogFields)
var varValue any
if strings.HasPrefix(h.Value, "{") &&
strings.HasSuffix(h.Value, "}") &&
strings.Count(h.Value, "{") == 1 {
// the value looks like a placeholder, so get its value
varValue, _ = repl.Get(strings.Trim(h.Value, "{}"))
} else if val, ok := vars[h.Value]; ok {
// the value is a key in the vars map
varValue = val
} else {
// the value is a constant string
varValue = h.Value
}
// Add the field to the extra log fields.
// We use zap.Any because it will reflect
// to the correct type for us.
extra.Add(zap.Any(h.Key, varValue))
return handlerErr
}
// Interface guards
var (
_ caddyhttp.MiddlewareHandler = (*LogAppend)(nil)
)
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