[Proof of Concept] Default tags implementation: provider and subnet/vpc resources

.changelog/17974.txt

@@ -0,0 +1,15 @@
+```release-note:note
+provider: New `default_tags` argument as a public preview for applying tags across all resources under a provider. Support for the functionality must be added to individual resources in the codebase and is only implemented for the `aws_subnet` and `aws_vpc` resources at this time. Until a general availability announcement, no compatibility promises are made with these provider arguments and their functionality.
+```
+
+```release-note:enhancement
+provider: Add `default_tags` argument (in public preview, see note above)
+
+
+```release-note:enhancement
+aws_subnet: Support provider-wide default tags (in public preview, see note above)
+```
+
+```release-note:enhancement
+aws_vpc: Support provider-wide default tags (in public preview, see note above)
+```

aws/config.go

@@ -191,9 +191,10 @@ type Config struct {
 	AllowedAccountIds   []string
 	ForbiddenAccountIds []string
 
-	Endpoints        map[string]string
-	IgnoreTagsConfig *keyvaluetags.IgnoreConfig
-	Insecure         bool
+	DefaultTagsConfig *keyvaluetags.DefaultConfig
+	Endpoints         map[string]string
+	IgnoreTagsConfig  *keyvaluetags.IgnoreConfig
+	Insecure          bool
 
 	SkipCredsValidation     bool
 	SkipGetEC2Platforms     bool
@@ -249,6 +250,7 @@ type AWSClient struct {
 	datapipelineconn                    *datapipeline.DataPipeline
 	datasyncconn                        *datasync.DataSync
 	daxconn                             *dax.DAX
+	DefaultTagsConfig                   *keyvaluetags.DefaultConfig
 	devicefarmconn                      *devicefarm.DeviceFarm
 	dlmconn                             *dlm.DLM
 	dmsconn                             *databasemigrationservice.DatabaseMigrationService
@@ -492,6 +494,7 @@ func (c *Config) Client() (interface{}, error) {
 		datapipelineconn:                    datapipeline.New(sess.Copy(&aws.Config{Endpoint: aws.String(c.Endpoints["datapipeline"])})),
 		datasyncconn:                        datasync.New(sess.Copy(&aws.Config{Endpoint: aws.String(c.Endpoints["datasync"])})),
 		daxconn:                             dax.New(sess.Copy(&aws.Config{Endpoint: aws.String(c.Endpoints["dax"])})),
+		DefaultTagsConfig:                   c.DefaultTagsConfig,
 		devicefarmconn:                      devicefarm.New(sess.Copy(&aws.Config{Endpoint: aws.String(c.Endpoints["devicefarm"])})),
 		dlmconn:                             dlm.New(sess.Copy(&aws.Config{Endpoint: aws.String(c.Endpoints["dlm"])})),
 		dmsconn:                             databasemigrationservice.New(sess.Copy(&aws.Config{Endpoint: aws.String(c.Endpoints["dms"])})),

aws/internal/keyvaluetags/key_value_tags.go

@@ -25,6 +25,11 @@ const (
 	ServerlessApplicationRepositoryTagKeyPrefix = `serverlessrepo:`
 )
 
+// DefaultConfig contains tags to default across all resources.
+type DefaultConfig struct {
+	Tags KeyValueTags
+}
+
 // IgnoreConfig contains various options for removing resource tags.
 type IgnoreConfig struct {
 	Keys        KeyValueTags
@@ -50,6 +55,36 @@ func (tags KeyValueTags) IgnoreAws() KeyValueTags {
 	return result
 }
 
+// MergeTags returns the result of keyvaluetags.Merge() on the given
+// DefaultConfig.Tags with KeyValueTags provided as an argument,
+// overriding the value of any tag with a matching key.
+func (dc *DefaultConfig) MergeTags(tags KeyValueTags) KeyValueTags {
+	if dc == nil || dc.Tags == nil {
+		return tags
+	}
+
+	return dc.Tags.Merge(tags)
+}
+
+// TagsEqual returns true if the given configuration's Tags
+// are equal to those passed in as an argument;
+// otherwise returns false
+func (dc *DefaultConfig) TagsEqual(tags KeyValueTags) bool {
+	if dc == nil || dc.Tags == nil {
+		return tags == nil
+	}
+
+	if tags == nil {
+		return false
+	}
+
+	if len(tags) == 0 {
+		return len(dc.Tags) == 0
+	}
+
+	return dc.Tags.ContainsAll(tags)
+}
+
 // IgnoreConfig returns any tags not removed by a given configuration.
 func (tags KeyValueTags) IgnoreConfig(config *IgnoreConfig) KeyValueTags {
 	if config == nil {
@@ -401,6 +436,27 @@ func (tags KeyValueTags) Hash() int {
 	return hash
 }
 
+// RemoveDefaultConfig returns tags not present in a DefaultConfig object
+// in addition to tags with key/value pairs that override those in a DefaultConfig;
+// however, if all tags present in the DefaultConfig object are equivalent to those
+// in the given KeyValueTags, then the KeyValueTags are returned, effectively
+// bypassing the need to remove differing tags.
+func (tags KeyValueTags) RemoveDefaultConfig(dc *DefaultConfig) KeyValueTags {
+	if dc == nil || dc.Tags == nil {
+		return tags
+	}
+
+	result := make(KeyValueTags)
+
+	for k, v := range tags {
+		if defaultVal, ok := dc.Tags[k]; !ok || !v.Equal(defaultVal) {
+			result[k] = v
+		}
+	}
+
+	return result
+}
+
 // String returns the default string representation of the KeyValueTags.
 func (tags KeyValueTags) String() string {
 	var builder strings.Builder