Use slim cloud-sdk instead of alpine

The gsutil command in alpine sometimes hangs.

io/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM google/cloud-sdk:alpine
+FROM google/cloud-sdk:slim
 
 RUN apk --no-cache add go musl-dev
 

migrate-pipeline/main.go

@@ -28,8 +28,8 @@ import (
 	v2 "google.golang.org/api/genomics/v2alpha1"
 )
 
-// The 'alpine' variant is about 10x smaller than the default.
-const cloudSDKImage = "google/cloud-sdk:alpine"
+// The 'slim' variant is about 3x smaller than the default.
+const cloudSDKImage = "google/cloud-sdk:slim"
 
 func main() {
 	var input v1.RunPipelineRequest

pipelines/internal/commands/run/run.go

@@ -156,7 +156,7 @@ var (
 	diskImage      = flags.String("disk-image", "", "optional image to pre-load onto the attached disk")
 	bootDiskSizeGb = flags.Int("boot-disk-size", 0, "if non-zero, specifies the boot disk size (in GB)")
 	privateAddress = flags.Bool("private-address", false, "use a private IP address")
-	cloudSDKImage  = flags.String("cloud-sdk-image", "google/cloud-sdk:183.0.0-alpine", "the cloud SDK image to use")
+	cloudSDKImage  = flags.String("cloud-sdk-image", "google/cloud-sdk:slim", "the cloud SDK image to use")
 	timeout        = flags.Duration("timeout", 0, "how long to wait before the operation is abandoned")
 	defaultImage   = flags.String("image", "bash", "the default image to use when executing commands")
 	attempts       = flags.Uint("attempts", 0, "number of attempts on non-fatal failure, using non-preemptible VM")