Drop support for Go 1.19

.github/workflows/ci.yml

@@ -99,7 +99,7 @@ jobs:
   compatibility-test:
     strategy:
       matrix:
-        go-version: ["~1.21.1", "~1.20.8", 1.19]
+        go-version: ["~1.21.1", "~1.20.8"]
         os: [ubuntu-latest, macos-latest, windows-latest]
         # GitHub Actions does not support arm* architectures on default
         # runners. It is possible to accomplish this with a self-hosted runner

.github/workflows/create-dependabot-pr.yml

@@ -10,7 +10,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v4
         with:
-          go-version: 1.19
+          go-version: "~1.21.1"
 
       - uses: actions/checkout@v3
 

CHANGELOG.md

@@ -24,6 +24,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Removed the deprecated `go.opentelemetry.io/otel/example/jaeger` package. (#4467)
 - Removed the deprecated `go.opentelemetry.io/otel/sdk/metric/aggregation` package. (#4468)
 - Removed the deprecated internal packages in `go.opentelemetry.io/otel/exporters/otlp` and its sub-packages. (#4469)
+- Dropped guaranteed support for versions of Go less than 1.20. (#4481)
 
 ## [1.17.0/0.40.0/0.0.5] 2023-08-28
 

Makefile

@@ -210,7 +210,7 @@ go-mod-tidy/%: DIR=$*
 go-mod-tidy/%: | crosslink
 	@echo "$(GO) mod tidy in $(DIR)" \
 		&& cd $(DIR) \
-		&& $(GO) mod tidy -compat=1.19
+		&& $(GO) mod tidy -compat=1.20
 
 .PHONY: lint-modules
 lint-modules: go-mod-tidy

README.md

@@ -55,19 +55,14 @@ Currently, this project supports the following environments.
 |---------|------------|--------------|
 | Ubuntu  | 1.21       | amd64        |
 | Ubuntu  | 1.20       | amd64        |
-| Ubuntu  | 1.19       | amd64        |
 | Ubuntu  | 1.21       | 386          |
 | Ubuntu  | 1.20       | 386          |
-| Ubuntu  | 1.19       | 386          |
 | MacOS   | 1.21       | amd64        |
 | MacOS   | 1.20       | amd64        |
-| MacOS   | 1.19       | amd64        |
 | Windows | 1.21       | amd64        |
 | Windows | 1.20       | amd64        |
-| Windows | 1.19       | amd64        |
 | Windows | 1.21       | 386          |
 | Windows | 1.20       | 386          |
-| Windows | 1.19       | 386          |
 
 While this project should work for other systems, no compatibility guarantees
 are made for those systems currently.

sdk/metric/go.mod

@@ -1,6 +1,6 @@
 module go.opentelemetry.io/otel/sdk/metric
 
-go 1.19
+go 1.20
 
 require (
 	github.com/go-logr/logr v1.2.4

sdk/metric/internal/aggregate/exponential_histogram_test.go

@@ -51,16 +51,13 @@ func TestExpoHistogramDataPointRecord(t *testing.T) {
 	t.Run("int64 MinMaxSum", testExpoHistogramMinMaxSumInt64)
 }
 
-// TODO: This can be defined in the test after we drop support for go1.19.
-type expoHistogramDataPointRecordTestCase[N int64 | float64] struct {
-	maxSize         int
-	values          []N
-	expectedBuckets expoBuckets
-	expectedScale   int
-}
-
 func testExpoHistogramDataPointRecord[N int64 | float64](t *testing.T) {
-	testCases := []expoHistogramDataPointRecordTestCase[N]{
+	testCases := []struct {
+		maxSize         int
+		values          []N
+		expectedBuckets expoBuckets
+		expectedScale   int
+	}{
 		{
 			maxSize: 4,
 			values:  []N{2, 4, 1},
@@ -747,14 +744,6 @@ func TestExponentialHistogramAggregation(t *testing.T) {
 }
 
 // TODO: This can be defined in the test after we drop support for go1.19.
-type exponentialHistogramAggregationTestCase[N int64 | float64] struct {
-	name      string
-	build     func() (Measure[N], ComputeAggregation)
-	input     [][]N
-	want      metricdata.ExponentialHistogram[N]
-	wantCount int
-}
-
 func testExponentialHistogramAggregation[N int64 | float64](t *testing.T) {
 	const (
 		maxSize  = 4
@@ -763,7 +752,13 @@ func testExponentialHistogramAggregation[N int64 | float64](t *testing.T) {
 		noSum    = false
 	)
 
-	tests := []exponentialHistogramAggregationTestCase[N]{
+	tests := []struct {
+		name      string
+		build     func() (Measure[N], ComputeAggregation)
+		input     [][]N
+		want      metricdata.ExponentialHistogram[N]
+		wantCount int
+	}{
 		{
 			name: "Delta Single",
 			build: func() (Measure[N], ComputeAggregation) {