MEDIUM: add parser option allowing to not serialize a section with a given name

Author: hdurand0710

config-parser/options/defaults-section-skip-on-write.go

@@ -0,0 +1,37 @@
+/*
+Copyright 2021 HAProxy Technologies
+
+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 options
+
+type defaultSectionsSkipOnWrite struct {
+	sectionNames map[string]struct{}
+}
+
+func (o defaultSectionsSkipOnWrite) Set(p *Parser) error {
+	p.DefaultSectionsSkipOnWrite = o.sectionNames
+	return nil
+}
+
+// sectionNames is a list of defaults section that the parser will not serialize even if existing in the configuration
+func DefaultSectionsSkipOnWrite(sectionNames []string) ParserOption {
+	names := make(map[string]struct{}, len(sectionNames))
+	for _, s := range sectionNames {
+		names[s] = struct{}{}
+	}
+	return defaultSectionsSkipOnWrite{
+		sectionNames: names,
+	}
+}

config-parser/options/options.go

@@ -23,16 +23,17 @@ import (
 )
 
 type Parser struct {
-	Path                    string
-	Reader                  io.Reader
-	Logger                  logger.Format // we always will have p.Options.LogPrefix
-	UseV2HTTPCheck          bool
-	UseMd5Hash              bool
-	UseListenSectionParsers bool
-	DisableUnProcessed      bool
-	Log                     bool
-	LogPrefix               string
-	NoNamedDefaultsFrom     bool
+	Path                       string
+	Reader                     io.Reader
+	Logger                     logger.Format // we always will have p.Options.LogPrefix
+	UseV2HTTPCheck             bool
+	UseMd5Hash                 bool
+	UseListenSectionParsers    bool
+	DisableUnProcessed         bool
+	Log                        bool
+	LogPrefix                  string
+	NoNamedDefaultsFrom        bool
+	DefaultSectionsSkipOnWrite map[string]struct{}
 }
 
 type ParserOption interface {

config-parser/tests/configs/haproxy_defaults-section-skip-on-write.go

@@ -0,0 +1,66 @@
+/*
+Copyright 2019 HAProxy Technologies
+
+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 configs
+
+const configDefaultSectionsSkipOnWrite_WithSectionName = `# _version=1
+# HAProxy Technologies
+# https://www.haproxy.com/
+
+global
+  master-worker
+
+defaults A
+  log global
+
+defaults B from A
+  maxconn 10
+
+defaults to_not_serialize
+
+frontend http from A
+  mode http
+  bind 0.0.0.0:80 name bind_1
+  bind :::80 v4v6 name bind_2
+  default_backend default_backend
+
+backend default_backend from A
+  mode http
+  http-request deny deny_status 400 # deny
+`
+
+const configDefaultSectionsSkipOnWrite_WithoutSectionName = `# _version=1
+# HAProxy Technologies
+# https://www.haproxy.com/
+
+global
+  master-worker
+
+defaults A
+  log global
+
+defaults B from A
+  maxconn 10
+
+frontend http from A
+  mode http
+  bind 0.0.0.0:80 name bind_1
+  bind :::80 v4v6 name bind_2
+  default_backend default_backend
+
+backend default_backend from A
+  mode http
+  http-request deny deny_status 400 # deny
+`

config-parser/tests/configs/parser_test.go

@@ -153,3 +153,48 @@ func TestListenSectionParsers(t *testing.T) {
 		t.Fatalf("configurations does not match")
 	}
 }
+
+func TestDefaultSectionsSkipOnWriteParsers(t *testing.T) {
+	tests := []struct {
+		Name                  string
+		Config                string
+		Result                string
+		DefaultsSectionToSkip []string
+	}{
+		{
+			"with option DefaultSectionsSkipOnWrite and section present",
+			configDefaultSectionsSkipOnWrite_WithSectionName, configDefaultSectionsSkipOnWrite_WithoutSectionName,
+			[]string{"to_not_serialize"},
+		},
+		{
+			"with option DefaultSectionsSkipOnWrite and section present - multiple options",
+			configDefaultSectionsSkipOnWrite_WithSectionName, configDefaultSectionsSkipOnWrite_WithoutSectionName,
+			[]string{"to_not_serialize", "to_not_serialize2"},
+		},
+		{
+			"no option DefaultSectionsSkipOnWrite and section absent",
+			configDefaultSectionsSkipOnWrite_WithoutSectionName, configDefaultSectionsSkipOnWrite_WithoutSectionName,
+			[]string{"to_not_serialize"},
+		},
+		{
+			"with option DefaultSectionsSkipOnWrite and section present different option name",
+			configDefaultSectionsSkipOnWrite_WithSectionName, configDefaultSectionsSkipOnWrite_WithSectionName,
+			[]string{"other"},
+		},
+	}
+
+	for _, tt := range tests {
+		var buffer bytes.Buffer
+		buffer.WriteString(tt.Config)
+		p, err := parser.New(options.DefaultSectionsSkipOnWrite(tt.DefaultsSectionToSkip), options.Reader(&buffer))
+		if err != nil {
+			t.Fatal(err.Error())
+		}
+
+		result := p.String() //nolint:ifshort
+		if result != tt.Result {
+			compare(t, tt.Config, tt.Result)
+			t.Fatalf("configurations does not match")
+		}
+	}
+}

config-parser/writer.go

@@ -81,12 +81,29 @@ func (p *configParser) String() string {
 			} else {
 				sName = string(section)
 			}
-			p.writeParsers(sName, p.Parsers[section][sectionName], &result, true)
+			serializeOk := p.shouldSerialize(section, sectionName)
+			if serializeOk {
+				p.writeParsers(sName, p.Parsers[section][sectionName], &result, true)
+			}
 		}
 	}
 	return result.String()
 }
 
+func (p *configParser) shouldSerialize(section Section, sectionName string) bool {
+	if section != Defaults {
+		return true
+	}
+
+	// For Defaults section, look if option DefaultSectionsSkipOnWrite is set
+	// if set, take it into into account to not serialize the defaults section with the option name
+	if len(p.Options.DefaultSectionsSkipOnWrite) == 0 {
+		return true
+	}
+	_, sectionToSkip := p.Options.DefaultSectionsSkipOnWrite[sectionName]
+	return !sectionToSkip
+}
+
 func (p *configParser) Save(filename string) error {
 	if p.Options.Log {
 		p.Options.Logger.Debugf("%ssaving configuration to file %s", p.Options.LogPrefix, filename)