Use I/O stream for provider logs interface

Providers must still update the implementaiton to actually gain any
benefit here, but this makes the provider interface a bit more sane.

providers/aws/fargate/cluster.go

@@ -2,6 +2,8 @@ package fargate
 
 import (
 	"fmt"
+	"io"
+	"io/ioutil"
 	"log"
 	"strings"
 	"sync"
@@ -11,6 +13,7 @@ import (
 	"github.com/aws/aws-sdk-go/service/cloudwatchlogs"
 	"github.com/aws/aws-sdk-go/service/ecs"
 	"github.com/cpuguy83/strongerrors"
+	"github.com/virtual-kubelet/virtual-kubelet/providers"
 	k8sTypes "k8s.io/apimachinery/pkg/types"
 )
 
@@ -310,9 +313,9 @@ func (c *Cluster) RemovePod(tag string) {
 }
 
 // GetContainerLogs returns the logs of a container from this cluster.
-func (c *Cluster) GetContainerLogs(namespace, podName, containerName string, tail int) (string, error) {
+func (c *Cluster) GetContainerLogs(namespace, podName, containerName string, opts providers.ContainerLogOpts) (io.ReadCloser, error) {
 	if c.cloudWatchLogGroupName == "" {
-		return "", fmt.Errorf("logs not configured, please specify a \"CloudWatchLogGroupName\"")
+		return nil, fmt.Errorf("logs not configured, please specify a \"CloudWatchLogGroupName\"")
 	}
 
 	prefix := fmt.Sprintf("%s_%s", buildTaskDefinitionTag(c.name, namespace, podName), containerName)
@@ -321,18 +324,18 @@ func (c *Cluster) GetContainerLogs(namespace, podName, containerName string, tai
 		LogStreamNamePrefix: aws.String(prefix),
 	})
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
 	// Nothing logged yet.
 	if len(describeResult.LogStreams) == 0 {
-		return "", nil
+		return nil, nil
 	}
 
 	logs := ""
 
 	err = client.logsapi.GetLogEventsPages(&cloudwatchlogs.GetLogEventsInput{
-		Limit:         aws.Int64(int64(tail)),
+		Limit:         aws.Int64(int64(opts.Tail)),
 		LogGroupName:  aws.String(c.cloudWatchLogGroupName),
 		LogStreamName: describeResult.LogStreams[0].LogStreamName,
 	}, func(page *cloudwatchlogs.GetLogEventsOutput, lastPage bool) bool {
@@ -348,8 +351,8 @@ func (c *Cluster) GetContainerLogs(namespace, podName, containerName string, tai
 	})
 
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
-	return logs, nil
+	return ioutil.NopCloser(strings.NewReader(logs)), nil
 }

providers/aws/provider.go

@@ -3,13 +3,13 @@ package aws
 import (
 	"context"
 	"fmt"
+	"io"
 	"log"
 	"time"
 
 	"github.com/virtual-kubelet/virtual-kubelet/manager"
 	"github.com/virtual-kubelet/virtual-kubelet/providers"
 	"github.com/virtual-kubelet/virtual-kubelet/providers/aws/fargate"
-
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -172,9 +172,9 @@ func (p *FargateProvider) GetPod(ctx context.Context, namespace, name string) (*
 }
 
 // GetContainerLogs retrieves the logs of a container by name from the provider.
-func (p *FargateProvider) GetContainerLogs(ctx context.Context, namespace, podName, containerName string, tail int) (string, error) {
+func (p *FargateProvider) GetContainerLogs(ctx context.Context, namespace, podName, containerName string, opts providers.ContainerLogOpts) (io.ReadCloser, error) {
 	log.Printf("Received GetContainerLogs request for %s/%s/%s.\n", namespace, podName, containerName)
-	return p.cluster.GetContainerLogs(namespace, podName, containerName, tail)
+	return p.cluster.GetContainerLogs(namespace, podName, containerName, opts)
 }
 
 // GetPodFullName retrieves the full pod name as defined in the provider context.

providers/aws/provider_test.go

@@ -15,8 +15,9 @@ import (
 	"github.com/aws/aws-sdk-go/service/ec2"
 	"github.com/aws/aws-sdk-go/service/ecs"
 	"github.com/aws/aws-sdk-go/service/iam"
+	"github.com/virtual-kubelet/virtual-kubelet/providers"
 	vkAWS "github.com/virtual-kubelet/virtual-kubelet/providers/aws"
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
@@ -282,13 +283,19 @@ func TestAWSFargateProviderPodLifecycle(t *testing.T) {
 		// Wait a few seconds for the logs to settle.
 		time.Sleep(10 * time.Second)
 
-		logs, err := provider.GetContainerLogs(context.Background(), "default", podName, "echo-container", 100)
+		logs, err := provider.GetContainerLogs(context.Background(), "default", podName, "echo-container", providers.ContainerLogOpts{Tail: 100})
 		if err != nil {
-			t.Error(err)
+			t.Fatal(err)
+		}
+		defer logs.Close()
+
+		b, err := ioutil.ReadAll(logs)
+		if err != nil {
+			t.Fatal(err)
 		}
 
 		// Test log output.
-		receivedLogs := strings.Split(logs, "\n")
+		receivedLogs := strings.Split(string(b), "\n")
 		expectedLogs := []string{
 			"Started",
 			pod.Spec.Containers[0].Env[0].Name + "=" + pod.Spec.Containers[0].Env[0].Value,