kadm: return defined errors for On functions

kerr errors are defined enough and can be better used with errors.As and
errors.Is.

pkg/kadm/configs.go

@@ -56,7 +56,7 @@ type ResourceConfigs []ResourceConfig
 // The fn is given a copy of the config. This function returns the copy as
 // well; any modifications within fn are modifications on the returned copy.
 //
-// If the resource does not exist, this returns an error indicating it is missing.
+// If the resource does not exist, this returns kerr.UnknownTopicOrPartition.
 func (rs ResourceConfigs) On(name string, fn func(*ResourceConfig) error) (ResourceConfig, error) {
 	for _, r := range rs {
 		if r.Name == name {
@@ -66,7 +66,7 @@ func (rs ResourceConfigs) On(name string, fn func(*ResourceConfig) error) (Resou
 			return r, fn(&r)
 		}
 	}
-	return ResourceConfig{}, errMissing(name)
+	return ResourceConfig{}, kerr.UnknownTopicOrPartition
 }
 
 // DescribeTopicConfigs returns the configuration for the requested topics.
@@ -196,7 +196,7 @@ type AlterConfigsResponses []AlterConfigsResponse
 // The fn is given a copy of the response. This function returns the copy as
 // well; any modifications within fn are modifications on the returned copy.
 //
-// If the resource does not exist, this returns an error indicating it is missing.
+// If the resource does not exist, this returns kerr.UnknownTopicOrPartition.
 func (rs AlterConfigsResponses) On(name string, fn func(*AlterConfigsResponse) error) (AlterConfigsResponse, error) {
 	for _, r := range rs {
 		if r.Name == name {
@@ -206,7 +206,7 @@ func (rs AlterConfigsResponses) On(name string, fn func(*AlterConfigsResponse) e
 			return r, fn(&r)
 		}
 	}
-	return AlterConfigsResponse{}, errMissing(name)
+	return AlterConfigsResponse{}, kerr.UnknownTopicOrPartition
 }
 
 // AlterTopicConfigs incrementally alters topic configuration values.

pkg/kadm/errors.go

@@ -9,14 +9,6 @@ import (
 	"github.com/twmb/franz-go/pkg/kmsg"
 )
 
-func errMissing(name string) error {
-	return fmt.Errorf("missing %q", name)
-}
-
-func errPartMissing(t string, p int32) error {
-	return fmt.Errorf("missing %q partition %d", t, p)
-}
-
 // AuthError can be returned from requests for resources that you are not
 // authorized for.
 type AuthError struct {

pkg/kadm/groups.go

@@ -150,7 +150,7 @@ func (ds DescribedGroups) Sorted() []DescribedGroup {
 // Modifications on a described group's inner fields are persisted to the
 // original map (because slices are pointers).
 //
-// If the group does not exist, this returns an error indicating it is missing.
+// If the group does not exist, this returns kerr.GroupIDNotFound.
 func (rs DescribedGroups) On(group string, fn func(*DescribedGroup) error) (DescribedGroup, error) {
 	if len(rs) > 0 {
 		r, ok := rs[group]
@@ -161,7 +161,7 @@ func (rs DescribedGroups) On(group string, fn func(*DescribedGroup) error) (Desc
 			return r, fn(&r)
 		}
 	}
-	return DescribedGroup{}, errMissing(group)
+	return DescribedGroup{}, kerr.GroupIDNotFound
 }
 
 // Topics returns a sorted list of all group names.
@@ -373,7 +373,7 @@ func (ds DeleteGroupResponses) Sorted() []DeleteGroupResponse {
 // The fn is given a copy of the response. This function returns the copy as
 // well; any modifications within fn are modifications on the returned copy.
 //
-// If the group does not exist, this returns an error indicating it is missing.
+// If the group does not exist, this returns kerr.GroupIDNotFound.
 func (rs DeleteGroupResponses) On(group string, fn func(*DeleteGroupResponse) error) (DeleteGroupResponse, error) {
 	if len(rs) > 0 {
 		r, ok := rs[group]
@@ -384,7 +384,7 @@ func (rs DeleteGroupResponses) On(group string, fn func(*DeleteGroupResponse) er
 			return r, fn(&r)
 		}
 	}
-	return DeleteGroupResponse{}, errMissing(group)
+	return DeleteGroupResponse{}, kerr.GroupIDNotFound
 }
 
 // DeleteGroups deletes all groups specified.
@@ -750,7 +750,7 @@ func (rs FetchOffsetsResponses) AllFailed() bool {
 // The fn is given a copy of the response. This function returns the copy as
 // well; any modifications within fn are modifications on the returned copy.
 //
-// If the group does not exist, this returns an error indicating it is missing.
+// If the group does not exist, this returns kerr.GroupIDNotFound.
 func (rs FetchOffsetsResponses) On(group string, fn func(*FetchOffsetsResponse) error) (FetchOffsetsResponse, error) {
 	if len(rs) > 0 {
 		r, ok := rs[group]
@@ -761,7 +761,7 @@ func (rs FetchOffsetsResponses) On(group string, fn func(*FetchOffsetsResponse)
 			return r, fn(&r)
 		}
 	}
-	return FetchOffsetsResponse{}, errMissing(group)
+	return FetchOffsetsResponse{}, kerr.GroupIDNotFound
 }
 
 // FetchManyOffsets issues a fetch offsets requests for each group specified.

pkg/kadm/topics.go

@@ -73,7 +73,7 @@ func (rs CreateTopicResponses) Sorted() []CreateTopicResponse {
 // The fn is given a copy of the response. This function returns the copy as
 // well; any modifications within fn are modifications on the returned copy.
 //
-// If the topic does not exist, this returns an error indicating it is missing.
+// If the topic does not exist, this returns kerr.UnknownTopicOrPartition.
 func (rs CreateTopicResponses) On(topic string, fn func(*CreateTopicResponse) error) (CreateTopicResponse, error) {
 	if len(rs) > 0 {
 		r, ok := rs[topic]
@@ -84,7 +84,7 @@ func (rs CreateTopicResponses) On(topic string, fn func(*CreateTopicResponse) er
 			return r, fn(&r)
 		}
 	}
-	return CreateTopicResponse{}, errMissing(topic)
+	return CreateTopicResponse{}, kerr.UnknownTopicOrPartition
 }
 
 // CreateTopics issues a create topics request with the given partitions,
@@ -197,7 +197,7 @@ func (rs DeleteTopicResponses) Sorted() []DeleteTopicResponse {
 // The fn is given a copy of the response. This function returns the copy as
 // well; any modifications within fn are modifications on the returned copy.
 //
-// If the topic does not exist, this returns an error indicating it is missing.
+// If the topic does not exist, this returns kerr.UnknownTopicOrPartition.
 func (rs DeleteTopicResponses) On(topic string, fn func(*DeleteTopicResponse) error) (DeleteTopicResponse, error) {
 	if len(rs) > 0 {
 		r, ok := rs[topic]
@@ -208,7 +208,7 @@ func (rs DeleteTopicResponses) On(topic string, fn func(*DeleteTopicResponse) er
 			return r, fn(&r)
 		}
 	}
-	return DeleteTopicResponse{}, errMissing(topic)
+	return DeleteTopicResponse{}, kerr.UnknownTopicOrPartition
 }
 
 // DeleteTopics issues a delete topics request for the given topic names with a
@@ -317,8 +317,8 @@ func (rs DeleteRecordsResponses) Sorted() []DeleteRecordsResponse {
 // The fn is given a copy of the response. This function returns the copy as
 // well; any modifications within fn are modifications on the returned copy.
 //
-// If the topic or partition does not exist, this returns an error indicating
-// it is missing.
+// If the topic or partition does not exist, this returns
+// kerr.UnknownTopicOrPartition.
 func (rs DeleteRecordsResponses) On(topic string, partition int32, fn func(*DeleteRecordsResponse) error) (DeleteRecordsResponse, error) {
 	if len(rs) > 0 {
 		t, ok := rs[topic]
@@ -332,7 +332,7 @@ func (rs DeleteRecordsResponses) On(topic string, partition int32, fn func(*Dele
 			}
 		}
 	}
-	return DeleteRecordsResponse{}, errPartMissing(topic, partition)
+	return DeleteRecordsResponse{}, kerr.UnknownTopicOrPartition
 }
 
 // DeleteRecords issues a delete records request for the given offsets. Per
@@ -411,7 +411,7 @@ func (rs CreatePartitionsResponses) Sorted() []CreatePartitionsResponse {
 // The fn is given a copy of the response. This function returns the copy as
 // well; any modifications within fn are modifications on the returned copy.
 //
-// If the topic does not exist, this returns an error indicating it is missing.
+// If the topic does not exist, this returns kerr.UnknownTopicOrPartition.
 func (rs CreatePartitionsResponses) On(topic string, fn func(*CreatePartitionsResponse) error) (CreatePartitionsResponse, error) {
 	if len(rs) > 0 {
 		r, ok := rs[topic]
@@ -422,7 +422,7 @@ func (rs CreatePartitionsResponses) On(topic string, fn func(*CreatePartitionsRe
 			return r, fn(&r)
 		}
 	}
-	return CreatePartitionsResponse{}, errMissing(topic)
+	return CreatePartitionsResponse{}, kerr.UnknownTopicOrPartition
 }
 
 // CreatePartitions issues a create partitions request for the given topics,