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Add support for changing the external listener hostname #6

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1 change: 1 addition & 0 deletions Dockerfile
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ ARG kafkaversion=3.6.1
ARG scalaversion=2.13

ENV KRAFT_CONTAINER_HOST_NAME=
ENV KRAFT_ADVERTISE_HOST_NAME=
ENV KRAFT_CREATE_TOPICS=
ENV KRAFT_PARTITIONS_PER_TOPIC=
ENV KRAFT_AUTO_CREATE_TOPICS=
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36 changes: 30 additions & 6 deletions README.md
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Expand Up @@ -17,6 +17,29 @@ $ docker run -e KRAFT_CONTAINER_HOST_NAME=kafka -e KRAFT_CREATE_TOPICS=topic-a,t
- Comma seperated values received by `KRAFT_CREATE_TOPICS` env will be used to create topics at startup time.
- The `KRAFT_AUTO_CREATE_TOPICS` env variable lets you turn off auto topic creation (`auto.create.topics.enable=false`). Default Kafka behavior is `true`.

### Access Across The Network

You can expose this Kafka broker to the network, in case any non-container applications need to access it or you want to access it from other machines.
This can also be useful if you run Linux in a VM (or via WSL) and want to allow your host machine to access Kafka.

Remember that this image **does not use Kafka authentication** so you should only do this on networks you trust.

```bash
$ hostname
my-linux-box
$ docker run -p 9093:9093 -e KRAFT_ADVERTISE_HOST_NAME=my-linux-box -e KRAFT_CONTAINER_HOST_NAME=kafka -e KRAFT_PARTITIONS_PER_TOPIC=3 -e KRAFT_AUTO_CREATE_TOPICS=true moeenz/docker-kafka-kraft
```

This allows other machines on the network to connect to Kafka at `my-linux-box:9093`.
`KRAFT_ADVERTISE_HOST_NAME` can also be an IP address if your network is not setup for hostnames:

```bash
$ ip addr show eth0
...
inet 192.168.0.2
$ docker run -p 9093:9093 -e KRAFT_ADVERTISE_HOST_NAME=192.168.0.2 -e KRAFT_CONTAINER_HOST_NAME=kafka -e KRAFT_PARTITIONS_PER_TOPIC=3 -e KRAFT_AUTO_CREATE_TOPICS=true moeenz/docker-kafka-kraft
```

### Compose Example

```yaml
Expand All @@ -35,12 +58,13 @@ services:

## Environment Variables

| Name | Type | Description | Example |
| -------------------------- | -------- | -------------------------------------------------------------- | ----------------------- |
| KRAFT_CONTAINER_HOST_NAME | string | Hostname for the running container as the Kafka listener | kafka |
| KRAFT_CREATE_TOPICS | []string | Comma separated list of topics to be created post server setup | topic-a,topic-b,topic-c |
| KRAFT_PARTITIONS_PER_TOPIC | int | Number of partitions per topic | 3 |
| KRAFT_AUTO_CREATE_TOPICS | string | `true` or `false`, Kafka default behavior is `true`. | false |
| Name | Type | Description | Example |
| -------------------------- | -------- | --------------------------------------------------------------------------------- | ----------------------- |
| KRAFT_CONTAINER_HOST_NAME | string | Hostname for the running container as the Kafka listener | kafka |
| KRAFT_ADVERTISE_HOST_NAME | string | Hostname or IP address that Kafka advertises externally. Defaults to `localhost`. | my-hostname |
| KRAFT_CREATE_TOPICS | []string | Comma separated list of topics to be created post server setup | topic-a,topic-b,topic-c |
| KRAFT_PARTITIONS_PER_TOPIC | int | Number of partitions per topic | 3 |
| KRAFT_AUTO_CREATE_TOPICS | string | `true` or `false`, Kafka default behavior is `true`. | false |

## Resources

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10 changes: 7 additions & 3 deletions docker-entrypoint.sh
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Expand Up @@ -19,14 +19,18 @@ else
echo "auto.create.topics.enable=${KRAFT_AUTO_CREATE_TOPICS}" >> $properties_file;
fi

if [ -z $KRAFT_ADVERTISE_HOST_NAME ]; then
KRAFT_ADVERTISE_HOST_NAME=localhost
fi

if [ -z $KRAFT_CONTAINER_HOST_NAME ]; then
echo "listeners=CONTROLLER://:19092,EXTERNAL://:9093" >> $properties_file;
echo "advertised.listeners=EXTERNAL://localhost:9093" >> $properties_file;
echo "advertised.listeners=EXTERNAL://${KRAFT_ADVERTISE_HOST_NAME}:9093" >> $properties_file;
echo "inter.broker.listener.name=EXTERNAL" >> $properties_file;
echo "listener.security.protocol.map=CONTROLLER:PLAINTEXT,EXTERNAL:PLAINTEXT" >> $properties_file;
else
echo "listeners=CONTROLLER://:19092,INTERNAL://:9092,EXTERNAL://:9093" >> $properties_file;
echo "advertised.listeners=INTERNAL://${KRAFT_CONTAINER_HOST_NAME}:9092,EXTERNAL://localhost:9093" >> $properties_file;
echo "advertised.listeners=INTERNAL://${KRAFT_CONTAINER_HOST_NAME}:9092,EXTERNAL://${KRAFT_ADVERTISE_HOST_NAME}:9093" >> $properties_file;
echo "inter.broker.listener.name=EXTERNAL" >> $properties_file;
echo "listener.security.protocol.map=CONTROLLER:PLAINTEXT,INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT" >> $properties_file;
fi
Expand Down Expand Up @@ -62,5 +66,5 @@ else
echo "==> ✅ Requested topics created.";
fi


echo "==> Connect to Kafka at ${KRAFT_ADVERTISE_HOST_NAME}:9093"
wait "$child";