feat: adds cloudmeta package

This adds cloudmeta package. For now it's only a basic interface for
working with different cloud metadata providers, like aws, gcp, azure.

pkg/cloudmeta/metadata.go

@@ -0,0 +1,72 @@
+// Copyright (C) 2024 ScyllaDB
+
+package cloudmeta
+
+import (
+	"context"
+	"errors"
+	"time"
+)
+
+// InstanceMetadata represents metadata returned by cloud provider.
+type InstanceMetadata struct {
+	InstanceType  string
+	CloudProvider CloudProvider
+}
+
+// CloudProvider is enum of supported cloud providers.
+type CloudProvider string
+
+// CloudProviderAWS represents aws provider.
+var CloudProviderAWS CloudProvider = "aws"
+
+// CloudMetadataProvider interface that each metadata provider should implement.
+type CloudMetadataProvider interface {
+	Metadata(ctx context.Context) (InstanceMetadata, error)
+}
+
+// CloudMeta is a wrapper around various cloud metadata providers.
+type CloudMeta struct {
+	providers []CloudMetadataProvider
+
+	providerTimeout time.Duration
+}
+
+// NewCloudMeta creates new CloudMeta provider.
+func NewCloudMeta() (*CloudMeta, error) {
+	// providers will initialized here and added to CloudMeta.providers.
+
+	const defaultTimeout = 5 * time.Second
+
+	return &CloudMeta{
+		providers:       []CloudMetadataProvider{},
+		providerTimeout: defaultTimeout,
+	}, nil
+}
+
+// GetInstanceMetadata tries to fetch instance metadata from AWS, GCP, Azure providers in order.
+func (cloud *CloudMeta) GetInstanceMetadata(ctx context.Context) (InstanceMetadata, error) {
+	var mErr error
+	for _, provider := range cloud.providers {
+		meta, err := cloud.runWithTimeout(ctx, provider)
+		if err != nil {
+			mErr = errors.Join(mErr, err)
+			continue
+		}
+		return meta, nil
+	}
+
+	return InstanceMetadata{}, mErr
+}
+
+func (cloud *CloudMeta) runWithTimeout(ctx context.Context, provider CloudMetadataProvider) (InstanceMetadata, error) {
+	ctx, cancel := context.WithTimeout(ctx, cloud.providerTimeout)
+	defer cancel()
+
+	return provider.Metadata(ctx)
+}
+
+// WithProviderTimeout sets per provider timeout.
+func (cloud *CloudMeta) WithProviderTimeout(providerTimeout time.Duration) {
+	cloud.providerTimeout = providerTimeout
+}

pkg/cloudmeta/metadata_test.go

@@ -0,0 +1,140 @@
+// Copyright (C) 2017 ScyllaDB
+
+package cloudmeta
+
+import (
+	"context"
+	"fmt"
+	"testing"
+)
+
+func TestGetInstanceMetadata(t *testing.T) {
+	t.Run("when there is no active providers", func(t *testing.T) {
+		cloudmeta := &CloudMeta{}
+
+		meta, err := cloudmeta.GetInstanceMetadata(context.Background())
+		if err != nil {
+			t.Fatalf("unexpected err: %v", err)
+		}
+		if meta.InstanceType != "" {
+			t.Fatalf("meta.InstanceType should be empty, got %v", meta.InstanceType)
+		}
+
+		if meta.CloudProvider != "" {
+			t.Fatalf("meta.CloudProvider should be empty, got %v", meta.CloudProvider)
+		}
+	})
+
+	t.Run("when there is only one active provider", func(t *testing.T) {
+		cloudmeta := &CloudMeta{
+			providers: []CloudMetadataProvider{newTestProvider(t, "test_provider_1", "x-test-1", nil)},
+		}
+
+		meta, err := cloudmeta.GetInstanceMetadata(context.Background())
+		if err != nil {
+			t.Fatalf("unexpected err: %v", err)
+		}
+
+		if meta.InstanceType != "x-test-1" {
+			t.Fatalf("meta.InstanceType should be 'x-test-1', got %v", meta.InstanceType)
+		}
+
+		if meta.CloudProvider != "test_provider_1" {
+			t.Fatalf("meta.CloudProvider should be 'test_provider_1', got %v", meta.CloudProvider)
+		}
+	})
+
+	t.Run("when there is more than one active provider", func(t *testing.T) {
+		cloudmeta := &CloudMeta{
+			providers: []CloudMetadataProvider{
+				newTestProvider(t, "test_provider_1", "x-test-1", nil),
+				newTestProvider(t, "test_provider_2", "x-test-2", nil),
+			},
+		}
+
+		// Only first one should be returned.
+		meta, err := cloudmeta.GetInstanceMetadata(context.Background())
+		if err != nil {
+			t.Fatalf("unexpected err: %v", err)
+		}
+
+		if meta.InstanceType != "x-test-1" {
+			t.Fatalf("meta.InstanceType should be 'x-test-1', got %v", meta.InstanceType)
+		}
+
+		if meta.CloudProvider != "test_provider_1" {
+			t.Fatalf("meta.CloudProvider should be 'test_provider_1', got %v", meta.CloudProvider)
+		}
+	})
+	t.Run("when there is more than one active provider, but first returns err", func(t *testing.T) {
+		cloudmeta := &CloudMeta{
+			providers: []CloudMetadataProvider{
+				newTestProvider(t, "test_provider_1", "x-test-1", fmt.Errorf("'test_provider_1' err")),
+				newTestProvider(t, "test_provider_2", "x-test-2", nil),
+			},
+		}
+
+		// Only first succesfull one should be returned.
+		meta, err := cloudmeta.GetInstanceMetadata(context.Background())
+		if err != nil {
+			t.Fatalf("unexpected err: %v", err)
+		}
+
+		if meta.InstanceType != "x-test-2" {
+			t.Fatalf("meta.InstanceType should be 'x-test-2', got %v", meta.InstanceType)
+		}
+
+		if meta.CloudProvider != "test_provider_2" {
+			t.Fatalf("meta.CloudProvider should be 'test_provider_2', got %v", meta.CloudProvider)
+		}
+	})
+
+	t.Run("when there is more than one active provider, but all returns err", func(t *testing.T) {
+		cloudmeta := &CloudMeta{
+			providers: []CloudMetadataProvider{
+				newTestProvider(t, "test_provider_1", "x-test-1", fmt.Errorf("'test_provider_1' err")),
+				newTestProvider(t, "test_provider_2", "x-test-2", fmt.Errorf("'test_provider_2' err")),
+			},
+		}
+
+		// Only first succesfull one should be returned.
+		meta, err := cloudmeta.GetInstanceMetadata(context.Background())
+		if err == nil {
+			t.Fatalf("expected err, but got: %v", err)
+		}
+
+		if meta.InstanceType != "" {
+			t.Fatalf("meta.InstanceType should be empty, got %v", meta.InstanceType)
+		}
+
+		if meta.CloudProvider != "" {
+			t.Fatalf("meta.CloudProvider should be empty, got %v", meta.CloudProvider)
+		}
+	})
+}
+
+func newTestProvider(t *testing.T, providerName, instanceType string, err error) *testProvider {
+	t.Helper()
+
+	return &testProvider{
+		name:         CloudProvider(providerName),
+		instanceType: instanceType,
+		err:          err,
+	}
+}
+
+type testProvider struct {
+	name         CloudProvider
+	instanceType string
+	err          error
+}
+
+func (tp testProvider) Metadata(ctx context.Context) (InstanceMetadata, error) {
+	if tp.err != nil {
+		return InstanceMetadata{}, tp.err
+	}
+	return InstanceMetadata{
+		CloudProvider: tp.name,
+		InstanceType:  tp.instanceType,
+	}, nil
+}