Here we are again, replacing more scary characters

For Fiesta / Kubernetes we are encountering (Container Image) version numbers with characters e.g. '@' which are not allowed. Filtering or replacing these characters at the fluent-bit level
is pretty hairy, so we opt to change this at the library level.
Currently, we are replacing all disallowed characters with '💀'.

The alternative of not doing this at the library level is to force every higher level logging system to deal with this (arbitrary) HSDP Logging limitation.

Note that practically every LogEvent field has a set of disallowed characters so to fully solve the issue we will have to add additional fields to the replaceMap and check each field in each message.

logging/client.go

@@ -45,6 +45,39 @@ var (
 	}
 )
 
+type replacer struct {
+	Regexp  *regexp.Regexp
+	Replace map[string]string
+}
+
+func (r replacer) replace(input string) string {
+	for k, v := range r.Replace {
+		input = strings.ReplaceAll(input, k, v)
+	}
+	return input
+}
+
+var (
+	replacerMap = map[string]replacer{
+		"applicationVersion": {
+			Regexp: regexp.MustCompile(`^[^&+;=?@|<>()]*$`),
+			Replace: map[string]string{
+				"@": "💀",
+				"&": "💀",
+				"+": "💀",
+				";": "💀",
+				"=": "💀",
+				"?": "💀",
+				"<": "💀",
+				">": "💀",
+				"|": "💀",
+				"(": "💀",
+				")": "💀",
+			},
+		},
+	}
+)
+
 // Config the client
 type Config struct {
 	Region       string
@@ -169,7 +202,9 @@ func (c *Client) do(req *http.Request, v interface{}) (*http.Response, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer resp.Body.Close()
+	defer func() {
+		_ = resp.Body.Close()
+	}()
 	if v != nil {
 		if w, ok := v.(io.Writer); ok {
 			_, err = io.Copy(w, resp.Body)
@@ -307,6 +342,12 @@ func (c *Client) performAndParseResponse(req *http.Request, msgs []Resource) (*S
 }
 
 func replaceScaryCharacters(msg *Resource) {
+	// Application version fixer
+	appVersion := replacerMap["applicationVersion"]
+	if !appVersion.Regexp.MatchString(msg.ApplicationVersion) {
+		msg.ApplicationVersion = appVersion.replace(msg.ApplicationVersion)
+	}
+
 	if len(msg.Custom) == 0 {
 		return
 	}

logging/client_test.go

@@ -454,3 +454,25 @@ func TestStoreResourceWithBearerToken(t *testing.T) {
 		t.Errorf("Expected HTTP 201, Got: %d", resp.StatusCode)
 	}
 }
+
+func TestApplicationVersionRegexp(t *testing.T) {
+	testsSet := []struct {
+		Field string
+		Input string
+		Fixed string
+	}{
+		{
+			Field: "applicationVersion",
+			Input: "public.ecr.aws/karpenter/controller@sha256:7779bf337cafe5080192f51819c5dc8a52ba6e7c4436ef9b2d164504d4ef8bea",
+			Fixed: "public.ecr.aws/karpenter/controller💀sha256:7779bf337cafe5080192f51819c5dc8a52ba6e7c4436ef9b2d164504d4ef8bea",
+		},
+	}
+
+	for _, test := range testsSet {
+		r := replacerMap[test.Field]
+		val := r.Regexp.MatchString(test.Input)
+		assert.False(t, val)
+		fixed := r.replace(test.Input)
+		assert.Equal(t, fixed, test.Fixed)
+	}
+}