Decouple otlp/otlptrace/otlptracehttp from otlp/internal and otlp/otlptrace/internal using gotmpl (#4401)

* Use template retry pkg in otlpconfig

* Template out all otlptrace internal

* Add envconfig pkg to otlptrace/internal

* Generate otlptrace/internal/otlpconfig

* Revert templatizing otlptracegrpc

* Add changes to changelog

* Fix lint

* Add partialsuccess to internal shared

* Use gotmpl to generate otlptracehttp/internal

* Add change to changelog

internal/shared/otlp/partialsuccess.go.tmpl

@@ -0,0 +1,67 @@
+// Code created by gotmpl. DO NOT MODIFY.
+// source: internal/shared/otlp/partialsuccess.go
+
+// Copyright The OpenTelemetry Authors
+//
+// 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 internal
+
+import "fmt"
+
+// PartialSuccess represents the underlying error for all handling
+// OTLP partial success messages.  Use `errors.Is(err,
+// PartialSuccess{})` to test whether an error passed to the OTel
+// error handler belongs to this category.
+type PartialSuccess struct {
+	ErrorMessage  string
+	RejectedItems int64
+	RejectedKind  string
+}
+
+var _ error = PartialSuccess{}
+
+// Error implements the error interface.
+func (ps PartialSuccess) Error() string {
+	msg := ps.ErrorMessage
+	if msg == "" {
+		msg = "empty message"
+	}
+	return fmt.Sprintf("OTLP partial success: %s (%d %s rejected)", msg, ps.RejectedItems, ps.RejectedKind)
+}
+
+// Is supports the errors.Is() interface.
+func (ps PartialSuccess) Is(err error) bool {
+	_, ok := err.(PartialSuccess)
+	return ok
+}
+
+// TracePartialSuccessError returns an error describing a partial success
+// response for the trace signal.
+func TracePartialSuccessError(itemsRejected int64, errorMessage string) error {
+	return PartialSuccess{
+		ErrorMessage:  errorMessage,
+		RejectedItems: itemsRejected,
+		RejectedKind:  "spans",
+	}
+}
+
+// MetricPartialSuccessError returns an error describing a partial success
+// response for the metric signal.
+func MetricPartialSuccessError(itemsRejected int64, errorMessage string) error {
+	return PartialSuccess{
+		ErrorMessage:  errorMessage,
+		RejectedItems: itemsRejected,
+		RejectedKind:  "metric data points",
+	}
+}

internal/shared/otlp/partialsuccess_test.go.tmpl

@@ -0,0 +1,46 @@
+// Code created by gotmpl. DO NOT MODIFY.
+// source: internal/shared/otlp/partialsuccess_test.go
+
+// Copyright The OpenTelemetry Authors
+//
+// 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 internal
+
+import (
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func requireErrorString(t *testing.T, expect string, err error) {
+	t.Helper()
+	require.NotNil(t, err)
+	require.Error(t, err)
+	require.True(t, errors.Is(err, PartialSuccess{}))
+
+	const pfx = "OTLP partial success: "
+
+	msg := err.Error()
+	require.True(t, strings.HasPrefix(msg, pfx))
+	require.Equal(t, expect, msg[len(pfx):])
+}
+
+func TestPartialSuccessFormat(t *testing.T) {
+	requireErrorString(t, "empty message (0 metric data points rejected)", MetricPartialSuccessError(0, ""))
+	requireErrorString(t, "help help (0 metric data points rejected)", MetricPartialSuccessError(0, "help help"))
+	requireErrorString(t, "what happened (10 metric data points rejected)", MetricPartialSuccessError(10, "what happened"))
+	requireErrorString(t, "what happened (15 spans rejected)", TracePartialSuccessError(15, "what happened"))
+}