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authorAaron Taylor <git@ataylor.io>2021-03-12 15:01:34 -0500
committerGitHub <noreply@github.com>2021-03-12 13:01:34 -0700
commitf137b82227f7b32b2ca036a89068c806a29a5ac7 (patch)
tree29bb7f2af1aa23f381151b353d32632b8d99bd9e
parent2a127ac3d1650052f39e93f277e1dfd8c7c730e4 (diff)
logging: add replace filter for static value replacement (#4029)
This filter is intended to be useful in scenarios where you may want to redact a value with a static string, giving you information that the field did previously exist and was present, but not revealing the value itself in the logs. This was inspired by work on adding more complete support for removing sensitive values from logs [1]. An example use case would be the Authorization header in request log output, for which the value should usually not be logged, but it may be quite useful for debugging to confirm that the header was present in the request. [1] https://github.com/caddyserver/caddy/issues/3958
-rw-r--r--caddytest/integration/caddyfile_adapt/log_filters.txt7
-rw-r--r--modules/logging/filters.go32
2 files changed, 36 insertions, 3 deletions
diff --git a/caddytest/integration/caddyfile_adapt/log_filters.txt b/caddytest/integration/caddyfile_adapt/log_filters.txt
index ab11807..0949c1d 100644
--- a/caddytest/integration/caddyfile_adapt/log_filters.txt
+++ b/caddytest/integration/caddyfile_adapt/log_filters.txt
@@ -5,7 +5,7 @@ log {
format filter {
wrap console
fields {
- request>headers>Authorization delete
+ request>headers>Authorization replace REDACTED
request>headers>Server delete
request>remote_addr ip_mask {
ipv4 24
@@ -30,7 +30,8 @@ log {
"encoder": {
"fields": {
"request\u003eheaders\u003eAuthorization": {
- "filter": "delete"
+ "filter": "replace",
+ "value": "REDACTED"
},
"request\u003eheaders\u003eServer": {
"filter": "delete"
@@ -66,4 +67,4 @@ log {
}
}
}
-} \ No newline at end of file
+}
diff --git a/modules/logging/filters.go b/modules/logging/filters.go
index a5a917d..a4e3c73 100644
--- a/modules/logging/filters.go
+++ b/modules/logging/filters.go
@@ -25,6 +25,7 @@ import (
func init() {
caddy.RegisterModule(DeleteFilter{})
+ caddy.RegisterModule(ReplaceFilter{})
caddy.RegisterModule(IPMaskFilter{})
}
@@ -57,6 +58,37 @@ func (DeleteFilter) Filter(in zapcore.Field) zapcore.Field {
return in
}
+// ReplaceFilter is a Caddy log field filter that
+// replaces the field with the indicated string.
+type ReplaceFilter struct {
+ Value string `json:"value,omitempty"`
+}
+
+// CaddyModule returns the Caddy module information.
+func (ReplaceFilter) CaddyModule() caddy.ModuleInfo {
+ return caddy.ModuleInfo{
+ ID: "caddy.logging.encoders.filter.replace",
+ New: func() caddy.Module { return new(ReplaceFilter) },
+ }
+}
+
+// UnmarshalCaddyfile sets up the module from Caddyfile tokens.
+func (f *ReplaceFilter) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
+ for d.Next() {
+ if d.NextArg() {
+ f.Value = d.Val()
+ }
+ }
+ return nil
+}
+
+// Filter filters the input field with the replacement value.
+func (f *ReplaceFilter) Filter(in zapcore.Field) zapcore.Field {
+ in.Type = zapcore.StringType
+ in.String = f.Value
+ return in
+}
+
// IPMaskFilter is a Caddy log field filter that
// masks IP addresses.
type IPMaskFilter struct {