HADOOP-15635. s3guard set-capacity command to fail fast if bucket is unguarded.

Contributed by Gabor Bota.

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/s3guard/S3GuardTool.java

@@ -479,6 +479,20 @@ public abstract class S3GuardTool extends Configured implements Tool {
     public int run(String[] args, PrintStream out) throws Exception {
       List<String> paths = parseArgs(args);
       Map<String, String> options = new HashMap<>();
+      String s3Path = paths.get(0);
+
+      // Check if DynamoDB url is set from arguments.
+      String metadataStoreUri = getCommandFormat().getOptValue(META_FLAG);
+      if(metadataStoreUri == null || metadataStoreUri.isEmpty()) {
+        // If not set, check if filesystem is guarded by creating an
+        // S3AFileSystem and check if hasMetadataStore is true
+        try (S3AFileSystem s3AFileSystem = (S3AFileSystem)
+            S3AFileSystem.newInstance(toUri(s3Path), getConf())){
+          Preconditions.checkState(s3AFileSystem.hasMetadataStore(),
+              "The S3 bucket is unguarded. " + getName()
+                  + " can not be used on an unguarded bucket.");
+        }
+      }
 
       String readCap = getCommandFormat().getOptValue(READ_FLAG);
       if (StringUtils.isNotEmpty(readCap)) {

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/s3guard/AbstractS3GuardToolTestBase.java

@@ -29,6 +29,7 @@ import java.net.URI;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.UUID;
 import java.util.concurrent.Callable;
 import java.util.concurrent.TimeUnit;
 
@@ -53,6 +54,7 @@ import org.apache.hadoop.util.ExitUtil;
 import org.apache.hadoop.util.StringUtils;
 
 import static org.apache.hadoop.fs.s3a.Constants.METADATASTORE_AUTHORITATIVE;
+import static org.apache.hadoop.fs.s3a.Constants.S3GUARD_DDB_TABLE_CREATE_KEY;
 import static org.apache.hadoop.fs.s3a.Constants.S3GUARD_DDB_TABLE_NAME_KEY;
 import static org.apache.hadoop.fs.s3a.Constants.S3GUARD_METASTORE_NULL;
 import static org.apache.hadoop.fs.s3a.Constants.S3_METADATA_STORE_IMPL;
@@ -296,7 +298,7 @@ public abstract class AbstractS3GuardToolTestBase extends AbstractS3ATestBase {
   }
 
   @Test
-  public void testSetCapacityFailFast() throws Exception{
+  public void testSetCapacityFailFastOnReadWriteOfZero() throws Exception{
     Configuration conf = getConfiguration();
     conf.set(S3GUARD_DDB_TABLE_NAME_KEY, getFileSystem().getBucket());
 
@@ -312,6 +314,21 @@ public abstract class AbstractS3GuardToolTestBase extends AbstractS3ATestBase {
         S3GuardTool.SetCapacity.WRITE_CAP_INVALID, () -> cmdW.run(argsW));
   }
 
+  @Test
+  public void testSetCapacityFailFastIfNotGuarded() throws Exception{
+    Configuration conf = getConfiguration();
+    conf.set(S3GUARD_DDB_TABLE_NAME_KEY, UUID.randomUUID().toString());
+    conf.set(S3GUARD_DDB_TABLE_CREATE_KEY, Boolean.FALSE.toString());
+    conf.set(S3_METADATA_STORE_IMPL, S3GUARD_METASTORE_NULL);
+
+    S3GuardTool.SetCapacity cmdR = new S3GuardTool.SetCapacity(conf);
+    String[] argsR = new String[]{cmdR.getName(),
+        "s3a://" + getFileSystem().getBucket()};
+
+    intercept(IllegalStateException.class, "unguarded",
+        () -> run(argsR));
+  }
+
   @Test
   public void testDestroyNoBucket() throws Throwable {
     intercept(FileNotFoundException.class,