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Kafka Backup: Tooling

Before you go, you need to add the kafka-backup.jar to your classpath:

export CLASSPATH="./path/to/kafka-backup.jar:$CLASSPATH"

If you are in the root directory of Kafka Backup, you can use:

export CLASSPATH="`pwd`/build/libs/kafka-backup.jar:$CLASSPATH"

SegmentCLI

Basic usage:

java de.azapps.kafkabackup.cli.SegmentCLI

List all records

java de.azapps.kafkabackup.cli.SegmentCLI \
  --list \
  --segment /path/to/segment_partition_123_from_offset_0000000123_records

Show key and value of a specific offset in a segment

java de.azapps.kafkabackup.cli.SegmentCLI --show --segment /path/to/segment_partition_123_from_offset_0000000123_records --offset 597

Formatting Options

Using the --formatter option you can customize how the keys and values of the messages are formatted. The default is the RawFormatter which prints the bytes as they are (i.e. as characters to the console.

Implemented options:

  • de.azapps.kafkabackup.cli.formatters.RawFormatter
  • de.azapps.kafkabackup.cli.formatters.UTF8Formatter
  • de.azapps.kafkabackup.cli.formatters.Base64Formatter

Example:

java de.azapps.kafkabackup.cli.SegmentCLI --list \
  --segment /path/to/segment_partition_123_from_offset_0000000123_records \
  --key-formatter de.azapps.kafkabackup.cli.formatters.Base64Formatter

SegmentIndexCLI

The segment index is required for faster access to the records in the segment file. It also simplifies the implementation of the idempotent sink connector. The segment index does not need to be backed up, but must exist before performing a restore.

List Index entries

Displays information about the records referenced in the index.

java de.azapps.kafkabackup.cli.SegmentIndexCLI --list \
  --segment-index /path/to/segment_partition_123_from_offset_0000000123_records \

Restore Index

Given a record file, restores the segment index for that file.

java de.azapps.kafkabackup.cli.SegmentIndexCLI --restore-index \
  --segment /path/to/segment_partition_123_from_offset_0000000123_records

Restoring all Segment Indexes

export TOPICDIR="/path/to/topicdir/"
for f in "$TOPICDIR"/segment_partition_*_records ; do
  java de.azapps.kafkabackup.cli.SegmentIndexCLI --restore-index \
  --segment $f
done

PartitionIndexCLI

The partition index contains the information about which offsets are located in which segment. This file too, does not need to be backed up but is required for restoration.

It is totally ok to delete old segments that are not needed anymore. But it is crucial to restore the partition index afterwards.

List Index entries

java de.azapps.kafkabackup.cli.PartitionIndexCLI --list \
  --partition-index /path/to/index_partition_123

Restore Partition Index

java de.azapps.kafkabackup.cli.PartitionIndexCLI --restore \
  --partition 0 \
  --topic-dir /path/to/topicdir/

Restore Indexes for all Partitions

export NUM_PARTITIONS=9
export TOPICDIR="/path/to/topicdir/"
for i in {0..$(( $NUM_PARTITIONS - 1 ))} ; do
    java de.azapps.kafkabackup.cli.PartitionIndexCLI --restore --partition $i --topic-dir "$TOPICDIR"
done

Completed segments processing

You may want to process completed segment files. Let's say you have your target.dir backed up to cloud storage daily. So you don't need to keep all the files locally then. To save some space you may delete completed segment files. There is bin/completed_segments.py script for your convenience.

To get some information on segment files just call script with path to your backup directory.

completed_segments.py /path/to/target_dir

To delete completed segments use -d option.

completed_segments.py -d /path/to/target_dir

You may keep last N completed segments by using -k N option.

If you need more complex processing you may just list completed segment files and pass them for further processing. E.g. to keep last 2 segments and shred the rest run the following command.

completed_segments.py -l -k 2 /path/to/target_dir | xargs shred -u