TUN-8734: add log collection for kubernetes

## Summary
Adds the log collector for K8s based deployments.

Closes TUN-8734

Author: lmpn

diagnostic/log_collector_docker.go

@@ -3,7 +3,6 @@ package diagnostic
 import (
 	"context"
 	"fmt"
-	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -44,40 +43,5 @@ func (collector *DockerLogCollector) Collect(ctx context.Context) (*LogInformati
 		collector.containerID,
 	)
 
-	stdoutReader, err := command.StdoutPipe()
-	if err != nil {
-		return nil, fmt.Errorf(
-			"error retrieving output from command '%s': %w",
-			command.String(),
-			err,
-		)
-	}
-
-	if err := command.Start(); err != nil {
-		return nil, fmt.Errorf(
-			"error running command '%s': %w",
-			command.String(),
-			err,
-		)
-	}
-
-	_, err = io.Copy(outputHandle, stdoutReader)
-	if err != nil {
-		return nil, fmt.Errorf(
-			"error copying output from %s to file %s: %w",
-			command.String(),
-			outputHandle.Name(),
-			err,
-		)
-	}
-
-	if err := command.Wait(); err != nil {
-		return nil, fmt.Errorf(
-			"error waiting from command '%s': %w",
-			command.String(),
-			err,
-		)
-	}
-
-	return NewLogInformation(outputHandle.Name(), true, false), nil
+	return PipeCommandOutputToFile(command, outputHandle)
 }

diagnostic/log_collector_kubernetes.go

@@ -0,0 +1,63 @@
+package diagnostic
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"time"
+)
+
+type KubernetesLogCollector struct {
+	containerID string // This member identifies the container by identifier or name
+	pod         string // This member identifies the pod where the container is deployed
+}
+
+func NewKubernetesLogCollector(containerID, pod string) *KubernetesLogCollector {
+	return &KubernetesLogCollector{
+		containerID,
+		pod,
+	}
+}
+
+func (collector *KubernetesLogCollector) Collect(ctx context.Context) (*LogInformation, error) {
+	tmp := os.TempDir()
+	outputHandle, err := os.Create(filepath.Join(tmp, logFilename))
+	if err != nil {
+		return nil, fmt.Errorf("error opening output file: %w", err)
+	}
+
+	defer outputHandle.Close()
+
+	var command *exec.Cmd
+	// Calculate 2 weeks ago
+	since := time.Now().Add(twoWeeksOffset).Format(time.RFC3339)
+	if collector.containerID != "" {
+		command = exec.CommandContext(
+			ctx,
+			"kubectl",
+			"logs",
+			collector.pod,
+			"--since-time=",
+			since,
+			"--tail=",
+			tailMaxNumberOfLines,
+			"-c",
+			collector.containerID,
+		)
+	} else {
+		command = exec.CommandContext(
+			ctx,
+			"kubectl",
+			"logs",
+			collector.pod,
+			"--since-time=",
+			since,
+			"--tail=",
+			tailMaxNumberOfLines,
+		)
+	}
+
+	return PipeCommandOutputToFile(command, outputHandle)
+}

diagnostic/log_collector_utils.go

@@ -0,0 +1,47 @@
+package diagnostic
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+)
+
+func PipeCommandOutputToFile(command *exec.Cmd, outputHandle *os.File) (*LogInformation, error) {
+	stdoutReader, err := command.StdoutPipe()
+	if err != nil {
+		return nil, fmt.Errorf(
+			"error retrieving output from command '%s': %w",
+			command.String(),
+			err,
+		)
+	}
+
+	if err := command.Start(); err != nil {
+		return nil, fmt.Errorf(
+			"error running command '%s': %w",
+			command.String(),
+			err,
+		)
+	}
+
+	_, err = io.Copy(outputHandle, stdoutReader)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"error copying output from %s to file %s: %w",
+			command.String(),
+			outputHandle.Name(),
+			err,
+		)
+	}
+
+	if err := command.Wait(); err != nil {
+		return nil, fmt.Errorf(
+			"error waiting from command '%s': %w",
+			command.String(),
+			err,
+		)
+	}
+
+	return NewLogInformation(outputHandle.Name(), true, false), nil
+}