<a id="migrate-confluent-kafka"></a>

# Migrate from Confluent Server to Confluent Kafka

To migrate a Confluent Platform cluster from the `confluent-server` package to
the `confluent-kafka` package, shut down the cluster, convert the
cluster metadata on each broker using the `kafka-metadata-shell`
and `kafka-metadata-recovery` tools, then restart the cluster with
the `confluent-kafka` package. The conversion strips out metadata
for `confluent-server` proprietary features so the cluster can run
on the open source `confluent-kafka` package.

## Prerequisites

This migration procedure applies to Confluent Platform versions 8.1.0 and later. To check your Confluent Platform version, run the following command.

```text
confluent local services kafka version
```

## Migration procedure

Perform the following steps on each broker node in your cluster.

1. Shut down the cluster. Ensure all broker processes are stopped across the entire cluster before you proceed.
   This prevents state changes during the migration.
2. On a broker node, create a temporary working directory for the migration. This allows you to work with a copy of the metadata,
   preventing accidental modification of live data.
   1. Define a variable for the temporary working directory:
      ```none
      OFFBOARD_WORKING_DIR="/tmp/offboard-wd"
      ```
   2. Set this variable to the path of your active `__cluster_metadata-0` directory:
      ```none
      METADATA_DIRECTORY="/var/lib/kafka/data/__cluster_metadata-0"
      ```
   3. Create the working directory and copy the current metadata into it:
      ```none
      mkdir -p "$OFFBOARD_WORKING_DIR"
      cp -r "$METADATA_DIRECTORY" "$OFFBOARD_WORKING_DIR/"
      ```
3. Use the `kafka-metadata-shell` tool to create a fresh snapshot from the copied metadata. This command
   writes a new `<offset-epoch>.checkpoint` file inside the copied metadata directory:
   ```none
   echo "write-snapshot -o $OFFBOARD_WORKING_DIR/__cluster_metadata-0" | kafka-metadata-shell -d "$OFFBOARD_WORKING_DIR/__cluster_metadata-0"
   ```
4. Run the `kafka-metadata-recovery` offboard command to convert the snapshot to a format compatible with open source Kafka.
   1. Find the latest checkpoint file created in the previous step by the `kafka-metadata-shell` tool:
      ```none
      CP_METADATA_SNAPSHOT_FILE=$(ls -1t "$OFFBOARD_WORKING_DIR"/__cluster_metadata-0/*.checkpoint | head -n 1)
      ```
   2. Run the offboard tool to generate the converted files:
      ```none
      kafka-metadata-recovery offboard \
        --checkpoint "$CP_METADATA_SNAPSHOT_FILE" \
        --out-directory "$OFFBOARD_WORKING_DIR"
      ```

   A successful run prints the location of the new files:
   ```none
   AK compatible Checkpoint file location:   /tmp/offboard-wd/0-1.checkpoint
   Bootstrap file location:  /tmp/offboard-wd/bootstrap.checkpoint
   kraft.version:    1
   Apache metadata.version:  4.1-IV1
   ```
5. Replace the original metadata files with the new, converted files.

   #### NOTE
   This step overwrites existing metadata files. Before proceeding, ensure you have a complete backup of your original `$METADATA_DIRECTORY`.

   1. Identify the new checkpoint file that was created in the working directory. The following command finds the checkpoint file
      while excluding the `bootstrap.checkpoint` file:
      ```none
      OFFBOARDED_SNAPSHOT_FILE=$(find "$OFFBOARD_WORKING_DIR" -name '*.checkpoint' ! -name 'bootstrap.checkpoint')
      ```
   2. Copy the new bootstrap file to the parent of the original metadata directory:
      ```none
      cp "$OFFBOARD_WORKING_DIR/bootstrap.checkpoint" "$(dirname "$METADATA_DIRECTORY")/"
      ```
   3. Copy the new data checkpoint file into the original metadata directory:
      ```none
      cp "$OFFBOARDED_SNAPSHOT_FILE" "$METADATA_DIRECTORY/"
      ```
6. Complete the following steps to finish the migration:
   1. Repeat steps two through five on every other broker node in the cluster.
   2. After all broker nodes are updated, restart the cluster using the `confluent-kafka` package.
      The cluster now boots using the converted metadata.

## Related content

- [Migrate from Kafka to Confluent Platform](migrating.md#migrate-ak-cc)
- [Manage Confluent Platform Licenses](license.md#cp-license-overview)