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HADOOP-16424. S3Guard fsck: Check internal consistency of the MetadataStore (#1691). Contributed by Gabor Bota.

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259
hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/s3guard/S3GuardFsck.java
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@ -24,12 +24,21 @@
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import com.amazonaws.services.dynamodbv2.document.Item;
import com.amazonaws.services.dynamodbv2.document.PrimaryKey;
import com.amazonaws.services.dynamodbv2.document.ScanOutcome;
import com.amazonaws.services.dynamodbv2.document.Table;
import com.amazonaws.services.dynamodbv2.document.internal.IteratorSupport;
import com.amazonaws.services.dynamodbv2.document.spec.GetItemSpec;
import com.amazonaws.services.dynamodbv2.xspec.ExpressionSpecBuilder;
import com.google.common.base.Preconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@ -38,10 +47,14 @@
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.s3a.S3AFileStatus;
import org.apache.hadoop.fs.s3a.S3AFileSystem;
import org.apache.hadoop.fs.s3a.Tristate;
import org.apache.hadoop.util.StopWatch;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;
import static org.apache.hadoop.fs.s3a.s3guard.PathMetadataDynamoDBTranslation.itemToPathMetadata;
import static org.apache.hadoop.fs.s3a.s3guard.PathMetadataDynamoDBTranslation.pathToKey;
import static org.apache.hadoop.fs.s3a.s3guard.PathMetadataDynamoDBTranslation.pathToParentKey;
/**
* Main class for the FSCK factored out from S3GuardTool
@ -51,6 +64,7 @@
* Functions:
* <ul>
* <li>Checking metadata consistency between S3 and metadatastore</li>
* <li>Checking the internal metadata consistency</li>
* </ul>
*/
public class S3GuardFsck {
@ -306,7 +320,7 @@ protected ComparePair compareFileStatusToPathMetadata(
}
if(msPathMetadata.getFileStatus().getVersionId() == null
|| s3FileStatus.getVersionId() == null ) {
|| s3FileStatus.getVersionId() == null) {
LOG.debug("Missing versionIDs skipped. A HEAD request is "
+ "required for each object to get the versionID.");
} else if(!s3FileStatus.getVersionId().equals(msFileStatus.getVersionId())) {
@ -349,7 +363,11 @@ public static class ComparePair {
this.msPathMetadata = pm;
this.s3DirListing = null;
this.msDirListing = null;
this.path = status.getPath();
if (status != null) {
this.path = status.getPath();
} else {
this.path = pm.getFileStatus().getPath();
}
}
ComparePair(List<FileStatus> s3DirListing, DirListingMetadata msDirListing) {
@ -396,6 +414,230 @@ public Path getPath() {
}
}
/**
* Check the DynamoDB metadatastore internally for consistency.
* <pre>
* Tasks to do here:
* - find orphan entries (entries without a parent).
* - find if a file's parent is not a directory (so the parent is a file).
* - find entries where the parent is a tombstone.
* - warn: no lastUpdated field.
* </pre>
*/
public List<ComparePair> checkDdbInternalConsistency(Path basePath)
throws IOException {
Preconditions.checkArgument(basePath.isAbsolute(), "path must be absolute");
List<ComparePair> comparePairs = new ArrayList<>();
String rootStr = basePath.toString();
LOG.info("Root for internal consistency check: {}", rootStr);
StopWatch stopwatch = new StopWatch();
stopwatch.start();
final Table table = metadataStore.getTable();
final String username = metadataStore.getUsername();
DDBTree ddbTree = new DDBTree();
/*
* I. Root node construction
* - If the root node is the real bucket root, a node is constructed instead of
* doing a query to the ddb because the bucket root is not stored.
* - If the root node is not a real bucket root then the entry is queried from
* the ddb and constructed from the result.
*/
DDBPathMetadata baseMeta;
if (!basePath.isRoot()) {
PrimaryKey rootKey = pathToKey(basePath);
final GetItemSpec spec = new GetItemSpec()
.withPrimaryKey(rootKey)
.withConsistentRead(true);
final Item baseItem = table.getItem(spec);
baseMeta = itemToPathMetadata(baseItem, username);
if (baseMeta == null) {
throw new FileNotFoundException(
"Base element metadata is null. " +
"This means the base path element is missing, or wrong path was " +
"passed as base path to the internal ddb consistency checker.");
}
} else {
baseMeta = new DDBPathMetadata(
new S3AFileStatus(Tristate.UNKNOWN, basePath, username)
);
}
DDBTreeNode root = new DDBTreeNode(baseMeta);
ddbTree.addNode(root);
ddbTree.setRoot(root);
/*
* II. Build and check the descendant tree:
* 1. query all nodes where the prefix is the given root, and put it in the tree
* 2. Check connectivity: check if each parent is in the hashmap
* - This is done in O(n): we only need to find the parent based on the
* path with a hashmap lookup.
* - Do a test if the graph is connected - if the parent is not in the
* hashmap, we found an orphan entry.
*
* 3. Do test the elements for errors:
* - File is a parent of a file.
* - Entries where the parent is tombstoned but the entries are not.
* - Warn on no lastUpdated field.
*
*/
ExpressionSpecBuilder builder = new ExpressionSpecBuilder();
builder.withCondition(
ExpressionSpecBuilder.S("parent")
.beginsWith(pathToParentKey(basePath))
);
final IteratorSupport<Item, ScanOutcome> resultIterator = table.scan(
builder.buildForScan()).iterator();
resultIterator.forEachRemaining(item -> {
final DDBPathMetadata pmd = itemToPathMetadata(item, username);
DDBTreeNode ddbTreeNode = new DDBTreeNode(pmd);
ddbTree.addNode(ddbTreeNode);
});
LOG.debug("Root: {}", ddbTree.getRoot());
for (Map.Entry<Path, DDBTreeNode> entry : ddbTree.getContentMap().entrySet()) {
final DDBTreeNode node = entry.getValue();
final ComparePair pair = new ComparePair(null, node.val);
// let's skip the root node when checking.
if (node.getVal().getFileStatus().getPath().isRoot()) {
continue;
}
if(node.getVal().getLastUpdated() == 0) {
pair.violations.add(Violation.NO_LASTUPDATED_FIELD);
}
// skip further checking the basenode which is not the actual bucket root.
if (node.equals(ddbTree.getRoot())) {
continue;
}
final Path parent = node.getFileStatus().getPath().getParent();
final DDBTreeNode parentNode = ddbTree.getContentMap().get(parent);
if (parentNode == null) {
pair.violations.add(Violation.ORPHAN_DDB_ENTRY);
} else {
if (!node.isTombstoned() && !parentNode.isDirectory()) {
pair.violations.add(Violation.PARENT_IS_A_FILE);
}
if(!node.isTombstoned() && parentNode.isTombstoned()) {
pair.violations.add(Violation.PARENT_TOMBSTONED);
}
}
if (!pair.violations.isEmpty()) {
comparePairs.add(pair);
}
node.setParent(parentNode);
}
// Create a handler and handle each violated pairs
S3GuardFsckViolationHandler handler =
new S3GuardFsckViolationHandler(rawFS, metadataStore);
comparePairs.forEach(handler::handle);
stopwatch.stop();
LOG.info("Total scan time: {}s", stopwatch.now(TimeUnit.SECONDS));
LOG.info("Scanned entries: {}", ddbTree.contentMap.size());
return comparePairs;
}
/**
* DDBTree is the tree that represents the structure of items in the DynamoDB.
*/
public static class DDBTree {
private final Map<Path, DDBTreeNode> contentMap = new HashMap<>();
private DDBTreeNode root;
public DDBTree() {
}
public Map<Path, DDBTreeNode> getContentMap() {
return contentMap;
}
public DDBTreeNode getRoot() {
return root;
}
public void setRoot(DDBTreeNode root) {
this.root = root;
}
public void addNode(DDBTreeNode pm) {
contentMap.put(pm.getVal().getFileStatus().getPath(), pm);
}
@Override
public String toString() {
return "DDBTree{" +
"contentMap=" + contentMap +
", root=" + root +
'}';
}
}
/**
* Tree node for DDBTree.
*/
private static final class DDBTreeNode {
private final DDBPathMetadata val;
private DDBTreeNode parent;
private final List<DDBPathMetadata> children;
private DDBTreeNode(DDBPathMetadata pm) {
this.val = pm;
this.parent = null;
this.children = new ArrayList<>();
}
public DDBPathMetadata getVal() {
return val;
}
public DDBTreeNode getParent() {
return parent;
}
public void setParent(DDBTreeNode parent) {
this.parent = parent;
}
public List<DDBPathMetadata> getChildren() {
return children;
}
public boolean isDirectory() {
return val.getFileStatus().isDirectory();
}
public S3AFileStatus getFileStatus() {
return val.getFileStatus();
}
public boolean isTombstoned() {
return val.isDeleted();
}
@Override
public String toString() {
return "DDBTreeNode{" +
"val=" + val +
", parent=" + parent +
", children=" + children +
'}';
}
}
/**
* Violation with severity and the handler.
* Defines the severity of the violation between 0-2
@ -437,7 +679,7 @@ public enum Violation {
AUTHORITATIVE_DIRECTORY_CONTENT_MISMATCH(1,
S3GuardFsckViolationHandler.AuthDirContentMismatch.class),
/**
* An entry in the MS is tombstoned, but the object is not deleted on S3
* An entry in the MS is tombstoned, but the object is not deleted on S3.
*/
TOMBSTONED_IN_MS_NOT_DELETED_IN_S3(0,
S3GuardFsckViolationHandler.TombstonedInMsNotDeletedInS3.class),
@ -462,7 +704,16 @@ public enum Violation {
* Don't worry too much if we don't have an etag.
*/
NO_ETAG(2,
S3GuardFsckViolationHandler.NoEtag.class);
S3GuardFsckViolationHandler.NoEtag.class),
/**
* The entry does not have a parent in ddb.
*/
ORPHAN_DDB_ENTRY(0, S3GuardFsckViolationHandler.OrphanDDBEntry.class),
/**
* The entry's lastUpdated field is empty.
*/
NO_LASTUPDATED_FIELD(2,
S3GuardFsckViolationHandler.NoLastUpdatedField.class);
private final int severity;
private final Class<? extends S3GuardFsckViolationHandler.ViolationHandler> handler;

30
hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/s3guard/S3GuardFsckViolationHandler.java
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@ -343,4 +343,34 @@ public String getError() {
return "The entry for the path is tombstoned in the MS.";
}
}
/**
* The violation handler there's no parent in the MetadataStore.
*/
public static class OrphanDDBEntry extends ViolationHandler {
public OrphanDDBEntry(S3GuardFsck.ComparePair comparePair) {
super(comparePair);
}
@Override
public String getError() {
return "The DDB entry is orphan - there is no parent in the MS.";
}
}
/**
* The violation handler when there's no last updated field for the entry.
*/
public static class NoLastUpdatedField extends ViolationHandler {
public NoLastUpdatedField(S3GuardFsck.ComparePair comparePair) {
super(comparePair);
}
@Override
public String getError() {
return "No lastUpdated field provided for the entry.";
}
}
}

42
hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/s3guard/S3GuardTool.java
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@ -1544,6 +1544,7 @@ private void vprintln(PrintStream out, String format, Object...
*/
static class Fsck extends S3GuardTool {
public static final String CHECK_FLAG = "check";
public static final String DDB_MS_CONSISTENCY_FLAG = "internal";
public static final String NAME = "fsck";
public static final String PURPOSE = "Compares S3 with MetadataStore, and "
@ -1553,10 +1554,12 @@ static class Fsck extends S3GuardTool {
"\t" + PURPOSE + "\n\n" +
"Common options:\n" +
" -" + CHECK_FLAG + " Check the metadata store for errors, but do "
+ "not fix any issues.\n";
+ "not fix any issues.\n"+
" -" + DDB_MS_CONSISTENCY_FLAG + " Check the dynamodb metadata store "
+ "for internal consistency.\n";
Fsck(Configuration conf) {
super(conf, CHECK_FLAG);
super(conf, CHECK_FLAG, DDB_MS_CONSISTENCY_FLAG);
}
@Override
@ -1578,6 +1581,21 @@ public int run(String[] args, PrintStream out) throws
}
int exitValue = EXIT_SUCCESS;
final CommandFormat commandFormat = getCommandFormat();
// check if there's more than one arguments
int flags = 0;
if (commandFormat.getOpt(CHECK_FLAG)) {
flags++;
}
if (commandFormat.getOpt(DDB_MS_CONSISTENCY_FLAG)) {
flags++;
}
if (flags > 1) {
out.println(USAGE);
throw invalidArgs("There should be only one parameter used for checking.");
}
String s3Path = paths.get(0);
try {
initS3AFileSystem(s3Path);
@ -1600,25 +1618,25 @@ public int run(String[] args, PrintStream out) throws
if (ms == null ||
!(ms instanceof DynamoDBMetadataStore)) {
errorln(s3Path + " path uses MS: " + ms);
errorln(s3Path + " path uses metadata store: " + ms);
errorln(NAME + " can be only used with a DynamoDB backed s3a bucket.");
errorln(USAGE);
return ERROR;
}
final CommandFormat commandFormat = getCommandFormat();
List<S3GuardFsck.ComparePair> violations;
if (commandFormat.getOpt(CHECK_FLAG)) {
// do the check
S3GuardFsck s3GuardFsck = new S3GuardFsck(fs, ms);
try {
final List<S3GuardFsck.ComparePair> comparePairs
= s3GuardFsck.compareS3ToMs(fs.qualify(root));
if (comparePairs.size() > 0) {
exitValue = EXIT_FAIL;
}
violations = s3GuardFsck.compareS3ToMs(fs.qualify(root));
} catch (IOException e) {
throw e;
}
} else if (commandFormat.getOpt(DDB_MS_CONSISTENCY_FLAG)) {
S3GuardFsck s3GuardFsck = new S3GuardFsck(fs, ms);
violations = s3GuardFsck.checkDdbInternalConsistency(fs.qualify(root));
} else {
errorln("No supported operation is selected.");
errorln(USAGE);
@ -1626,6 +1644,12 @@ public int run(String[] args, PrintStream out) throws
}
out.flush();
// We fail if there were compare pairs, as the returned compare pairs
// contain issues.
if (violations == null || violations.size() > 0) {
exitValue = EXIT_FAIL;
}
return exitValue;
}
}

39
hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/s3guard.md
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@ -923,10 +923,47 @@ Metadata Store Diagnostics:
table={ ... }
write-capacity=20
```
*Note*: There is a limit to how many times in a 24 hour period the capacity
of a bucket can be changed, either through this command or the AWS console.
### Check the consistency of the metadata store, `s3guard fsck`
Compares S3 with MetadataStore, and returns a failure status if any
rules or invariants are violated. Only works with DynamoDB metadata stores.
```bash
hadoop s3guard fsck [-check | -internal] (s3a://BUCKET | s3a://PATH_PREFIX)
```
`-check` operation checks the metadata store from the S3 perspective, but
does not fix any issues.
The consistency issues will be logged in ERROR loglevel.
`-internal` operation checks the internal consistency of the metadata store,
but does not fix any issues.
The errors found will be logged at the ERROR log level.
*Note*: `-check` and `-internal` operations can be used only as separate
commands. Running `fsck` with both will result in an error.
Example
```bash
hadoop s3guard fsck -check s3a://ireland-1/path_prefix/
```
Checks the metadata store while iterating through the S3 bucket.
The path_prefix will be used as the root element of the check.
```bash
hadoop s3guard fsck -internal s3a://ireland-1/path_prefix/
```
Checks the metadata store internal consistency.
The path_prefix will be used as the root element of the check.
## Debugging and Error Handling
If you run into network connectivity issues, or have a machine failure in the

120
hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/s3guard/ITestS3GuardFsck.java
View File

@ -435,10 +435,126 @@ public void testTombstonedInMsNotDeletedInS3() throws Exception {
assertComparePairsSize(comparePairs, 1);
// check fil1 that there's the violation
// check if the violation is there
checkForViolationInPairs(file, comparePairs,
S3GuardFsck.Violation.TOMBSTONED_IN_MS_NOT_DELETED_IN_S3);
// check the child that there's no NO_ETAG violation
} finally {
cleanup(file, cwd);
}
}
@Test
public void checkDdbInternalConsistency() throws Exception {
final S3GuardFsck s3GuardFsck = new S3GuardFsck(rawFs, metadataStore);
final DynamoDBMetadataStore ms =
(DynamoDBMetadataStore) guardedFs.getMetadataStore();
s3GuardFsck.checkDdbInternalConsistency(
new Path("s3a://" + guardedFs.getBucket() + "/"));
}
@Test
public void testDdbInternalNoLastUpdatedField() throws Exception {
final Path cwd = path("/" + getMethodName() + "-" + UUID.randomUUID());
final Path file = new Path(cwd, "file");
try {
final S3AFileStatus s3AFileStatus = new S3AFileStatus(100, 100, file, 100,
"test", "etag", "version");
final PathMetadata pathMetadata = new PathMetadata(s3AFileStatus);
pathMetadata.setLastUpdated(0);
metadataStore.put(pathMetadata);
final S3GuardFsck s3GuardFsck = new S3GuardFsck(rawFs, metadataStore);
final List<S3GuardFsck.ComparePair> comparePairs =
s3GuardFsck.checkDdbInternalConsistency(cwd);
assertComparePairsSize(comparePairs, 1);
// check if the violation is there
checkForViolationInPairs(file, comparePairs,
S3GuardFsck.Violation.NO_LASTUPDATED_FIELD);
} finally {
cleanup(file, cwd);
}
}
@Test
public void testDdbInternalOrphanEntry() throws Exception {
final Path cwd = path("/" + getMethodName() + "-" + UUID.randomUUID());
final Path parentDir = new Path(cwd, "directory");
final Path file = new Path(parentDir, "file");
try {
final S3AFileStatus s3AFileStatus = new S3AFileStatus(100, 100, file, 100,
"test", "etag", "version");
final PathMetadata pathMetadata = new PathMetadata(s3AFileStatus);
pathMetadata.setLastUpdated(1000);
metadataStore.put(pathMetadata);
metadataStore.forgetMetadata(parentDir);
final S3GuardFsck s3GuardFsck = new S3GuardFsck(rawFs, metadataStore);
final List<S3GuardFsck.ComparePair> comparePairs =
s3GuardFsck.checkDdbInternalConsistency(cwd);
// check if the violation is there
assertComparePairsSize(comparePairs, 1);
checkForViolationInPairs(file, comparePairs,
S3GuardFsck.Violation.ORPHAN_DDB_ENTRY);
} finally {
cleanup(file, cwd);
}
}
@Test
public void testDdbInternalParentIsAFile() throws Exception {
final Path cwd = path("/" + getMethodName() + "-" + UUID.randomUUID());
final Path parentDir = new Path(cwd, "directory");
final Path file = new Path(parentDir, "file");
try {
final S3AFileStatus s3AFileStatus = new S3AFileStatus(100, 100, file, 100,
"test", "etag", "version");
final PathMetadata pathMetadata = new PathMetadata(s3AFileStatus);
pathMetadata.setLastUpdated(1000);
metadataStore.put(pathMetadata);
final S3AFileStatus dirAsFile = MetadataStoreTestBase
.basicFileStatus(parentDir, 1, false, 1);
final PathMetadata dirAsFilePm = new PathMetadata(dirAsFile);
dirAsFilePm.setLastUpdated(100);
metadataStore.put(dirAsFilePm);
final S3GuardFsck s3GuardFsck = new S3GuardFsck(rawFs, metadataStore);
final List<S3GuardFsck.ComparePair> comparePairs =
s3GuardFsck.checkDdbInternalConsistency(cwd);
// check if the violation is there
assertComparePairsSize(comparePairs, 1);
checkForViolationInPairs(file, comparePairs,
S3GuardFsck.Violation.PARENT_IS_A_FILE);
} finally {
cleanup(file, cwd);
}
}
@Test
public void testDdbInternalParentTombstoned() throws Exception {
final Path cwd = path("/" + getMethodName() + "-" + UUID.randomUUID());
final Path parentDir = new Path(cwd, "directory");
final Path file = new Path(parentDir, "file");
try {
final S3AFileStatus s3AFileStatus = new S3AFileStatus(100, 100, file, 100,
"test", "etag", "version");
final PathMetadata pathMetadata = new PathMetadata(s3AFileStatus);
pathMetadata.setLastUpdated(1000);
metadataStore.put(pathMetadata);
metadataStore.delete(parentDir, null);
final S3GuardFsck s3GuardFsck = new S3GuardFsck(rawFs, metadataStore);
final List<S3GuardFsck.ComparePair> comparePairs =
s3GuardFsck.checkDdbInternalConsistency(cwd);
// check if the violation is there
assertComparePairsSize(comparePairs, 1);
checkForViolationInPairs(file, comparePairs,
S3GuardFsck.Violation.PARENT_TOMBSTONED);
} finally {
cleanup(file, cwd);
}

35
hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/s3guard/ITestS3GuardToolDynamoDB.java
View File

@ -304,11 +304,11 @@ public void testCLIFsckWithoutParam() throws Exception {
@Test
public void testCLIFsckWithParam() throws Exception {
LOG.info("This test serves the purpose to run fsck with the correct " +
"parameters, so there will be no exception thrown.");
final int result = run(S3GuardTool.Fsck.NAME, "-check",
"s3a://" + getFileSystem().getBucket());
LOG.info("This test serves the purpose to run fsck with the correct " +
"parameters, so there will be no exception thrown. " +
"The return value of the run: {}", result);
LOG.info("The return value of the run: {}", result);
}
@Test
@ -324,4 +324,33 @@ public void testCLIFsckFailInitializeFs() throws Exception {
() -> run(S3GuardTool.Fsck.NAME, "-check",
"s3a://this-bucket-does-not-exist-" + UUID.randomUUID()));
}
@Test
public void testCLIFsckDDbInternalWrongS3APath() throws Exception {
intercept(FileNotFoundException.class, "wrong path",
() -> run(S3GuardTool.Fsck.NAME, "-"+Fsck.DDB_MS_CONSISTENCY_FLAG,
"s3a://" + getFileSystem().getBucket() + "/" + UUID.randomUUID()));
}
@Test
public void testCLIFsckDDbInternalParam() throws Exception {
describe("This test serves the purpose to run fsck with the correct " +
"parameters, so there will be no exception thrown.");
final int result = run(S3GuardTool.Fsck.NAME,
"-" + Fsck.DDB_MS_CONSISTENCY_FLAG,
"s3a://" + getFileSystem().getBucket());
LOG.info("The return value of the run: {}", result);
}
@Test
public void testCLIFsckCheckExclusive() throws Exception {
describe("There should be only one check param when running fsck." +
"If more then one param is passed, the command should fail." +
"This provide exclusive run for checks so the user is able to define " +
"the order of checking.");
intercept(ExitUtil.ExitException.class, "only one parameter",
() -> run(S3GuardTool.Fsck.NAME,
"-" + Fsck.DDB_MS_CONSISTENCY_FLAG, "-" + Fsck.CHECK_FLAG,
"s3a://" + getFileSystem().getBucket()));
}
}