slack/slack-sink/README.adoc

# Camel-Kafka-connector Slack Sink

This is an example for Camel-Kafka-connector Slack Sink 

## Standalone

### What is needed

- A Slack app
- A Slack channel

### Setting up Slack

You'll need a workspace and a channel.

In your Slack settings, create an app.

Add the following permissions to your Bot Token scopes:

  * channels:history
  * channels:read

Install the app on your workspace and select the channel you want to consume from. 

Use the Bot User OAuth Access Token as token for this example.

### Running Kafka

```
$KAFKA_HOME/bin/zookeeper-server-start.sh $KAFKA_HOME/config/zookeeper.properties
$KAFKA_HOME/bin/kafka-server-start.sh $KAFKA_HOME/config/server.properties
$KAFKA_HOME/bin/kafka-topics.sh --create --bootstrap-server localhost:9092 --replication-factor 1 --partitions 1 --topic mytopic
```

### Setting up the needed bits and running the example

You'll need to setup the plugin.path property in your kafka

Open the `$KAFKA_HOME/config/connect-standalone.properties`

and set the `plugin.path` property to your choosen location

In this example we'll use `/home/oscerd/connectors/`

```
> cd /home/oscerd/connectors/
> wget https://repo1.maven.org/maven2/org/apache/camel/kafkaconnector/camel-slack-kafka-connector/0.11.5/camel-slack-kafka-connector-0.11.5-package.tar.gz
> untar.gz camel-slack-kafka-connector-0.11.5-package.tar.gz
```

Now it's time to setup the connectors

Open the Slack sink configuration file

```
name=CamelSlackSinkConnector
connector.class=org.apache.camel.kafkaconnector.slack.CamelSlackSinkConnector
key.converter=org.apache.kafka.connect.storage.StringConverter
value.converter=org.apache.kafka.connect.storage.StringConverter

topics=mytopic

camel.sink.path.channel=general
camel.component.slack.webhookUrl=<your_webhook_url>
```

Now you can run the example

```
$KAFKA_HOME/bin/connect-standalone.sh $KAFKA_HOME/config/connect-standalone.properties config/CamelSlackSinkConnector.properties
```

Check for messages in your channel

In another terminal, using kafkacat, you should be able to send messages

```
> echo "Hello from Apache Camel" | ./kafkacat -b localhost:9092 -t mytopic 
% Auto-selecting Producer mode (use -P or -C to override)
```

## Openshift

### What is needed

- A Slack App
- A Slack channel
- An Openshift instance

### Running Kafka using Strimzi Operator

First we install the Strimzi operator and use it to deploy the Kafka broker and Kafka Connect into our OpenShift project.
We need to create security objects as part of installation so it is necessary to switch to admin user.
If you use Minishift, you can do it with the following command:

[source,bash,options="nowrap"]
----
oc login -u system:admin
----

We will use OpenShift project `myproject`.
If it doesn't exist yet, you can create it using following command:

[source,bash,options="nowrap"]
----
oc new-project myproject
----

If the project already exists, you can switch to it with:

[source,bash,options="nowrap"]
----
oc project myproject
----

We can now install the Strimzi operator into this project:

[source,bash,options="nowrap",subs="attributes"]
----
oc apply -f https://github.com/strimzi/strimzi-kafka-operator/releases/download/0.20.1/strimzi-cluster-operator-0.20.1.yaml
----

Next we will deploy a Kafka broker cluster and a Kafka Connect cluster and then create a Kafka Connect image with the Debezium connectors installed:

[source,bash,options="nowrap",subs="attributes"]
----
# Deploy a single node Kafka broker
oc apply -f https://github.com/strimzi/strimzi-kafka-operator/raw/0.20.1/examples/kafka/kafka-persistent-single.yaml

# Deploy a single instance of Kafka Connect with no plug-in installed
oc apply -f https://github.com/strimzi/strimzi-kafka-operator/raw/0.20.1/examples/connect/kafka-connect-s2i-single-node-kafka.yaml
----

Optionally enable the possibility to instantiate Kafka Connectors through specific custom resource:
[source,bash,options="nowrap"]
----
oc annotate kafkaconnects2is my-connect-cluster strimzi.io/use-connector-resources=true
----

### Add Camel Kafka connector binaries

Strimzi uses `Source2Image` builds to allow users to add their own connectors to the existing Strimzi Docker images.
We now need to build the connectors and add them to the image,
if you have built the whole project (`mvn clean package`) decompress the connectors you need in a folder (i.e. like `my-connectors/`)
so that each one is in its own subfolder
(alternatively you can download the latest officially released and packaged connectors from maven):

So we need to do something like this:

```
> cd my-connectors/
> wget https://repo1.maven.org/maven2/org/apache/camel/kafkaconnector/camel-slack-kafka-connector/0.11.5/camel-slack-kafka-connector-0.11.5-package.tar.gz
> untar.gz camel-slack-kafka-connector-0.11.5-package.tar.gz
```

Now we can start the build 

[source,bash,options="nowrap"]
----
oc start-build my-connect-cluster-connect --from-dir=./my-connectors/ --follow
----

We should now wait for the rollout of the new image to finish and the replica set with the new connector to become ready.
Once it is done, we can check that the connectors are available in our Kafka Connect cluster.
Strimzi is running Kafka Connect in a distributed mode.

To check the available connector plugins, you can run the following command:

[source,bash,options="nowrap"]
----
oc exec -i `oc get pods --field-selector status.phase=Running -l strimzi.io/name=my-connect-cluster-connect -o=jsonpath='{.items[0].metadata.name}'` -- curl -s http://my-connect-cluster-connect-api:8083/connector-plugins
----

You should see something like this:

[source,json,options="nowrap"]
----
[{"class":"org.apache.camel.kafkaconnector.CamelSinkConnector","type":"sink","version":"0.11.5"},{"class":"org.apache.camel.kafkaconnector.CamelSourceConnector","type":"source","version":"0.11.5"},{"class":"org.apache.camel.kafkaconnector.slack.CamelSlackSinkConnector","type":"sink","version":"0.11.5"},{"class":"org.apache.camel.kafkaconnector.slack.CamelSlackSourceConnector","type":"source","version":"0.11.5"},{"class":"org.apache.kafka.connect.file.FileStreamSinkConnector","type":"sink","version":"2.5.0"},{"class":"org.apache.kafka.connect.file.FileStreamSourceConnector","type":"source","version":"2.5.0"},{"class":"org.apache.kafka.connect.mirror.MirrorCheckpointConnector","type":"source","version":"1"},{"class":"org.apache.kafka.connect.mirror.MirrorHeartbeatConnector","type":"source","version":"1"},{"class":"org.apache.kafka.connect.mirror.MirrorSourceConnector","type":"source","version":"1"}]
----

### Set the Bot Token as secret (optional)

You can also set the webhook option as secret, you'll need to edit the file config/slack-webhook.properties with the correct credentials and then execute the following command

[source,bash,options="nowrap"]
----
oc create secret generic slack-webhook --from-file=config/openshift/slack-webhook.properties
----

Now we need to edit KafkaConnectS2I custom resource to reference the secret. For example:

[source,bash,options="nowrap"]
----
spec:
  # ...
  config:
    config.providers: file
    config.providers.file.class: org.apache.kafka.common.config.provider.FileConfigProvider
  #...
  externalConfiguration:
    volumes:
      - name: slack-webhook
        secret:
          secretName: slack-webhook
----

In this way the secret slack-webhook will be mounted as volume with path /opt/kafka/external-configuration/slack-webhook/

### Create connector instance

Now we can create some instance of the Slack sink connector:

[source,bash,options="nowrap"]
----
oc exec -i `oc get pods --field-selector status.phase=Running -l strimzi.io/name=my-connect-cluster-connect -o=jsonpath='{.items[0].metadata.name}'` -- curl -X POST \
    -H "Accept:application/json" \
    -H "Content-Type:application/json" \
    http://my-connect-cluster-connect-api:8083/connectors -d @- <<'EOF'
{
  "name": "slack-sink-connector",
  "config": {
    "connector.class": "org.apache.camel.kafkaconnector.slack.CamelSlackSinkConnector",
    "tasks.max": "1",
    "key.converter": "org.apache.kafka.connect.storage.StringConverter",
    "value.converter": "org.apache.kafka.connect.storage.StringConverter",
    "topics": "slack-topic",
    "camel.sink.path.channel": "general",
    "camel.component.slack.webhookUrl": "<webhook_url>"
  }
}
EOF
----

Altenatively, if have enabled `use-connector-resources`, you can create the connector instance by creating a specific custom resource:

[source,bash,options="nowrap"]
----
oc apply -f - << EOF
apiVersion: kafka.strimzi.io/v1alpha1
kind: KafkaConnector
metadata:
  name: slack-sink-connector
  namespace: myproject
  labels:
    strimzi.io/cluster: my-connect-cluster
spec:
  class: org.apache.camel.kafkaconnector.slack.CamelSlackSinkConnector
  tasksMax: 1
  config:
    key.converter: org.apache.kafka.connect.storage.StringConverter
    value.converter: org.apache.kafka.connect.storage.StringConverter
    topics: slack-topic
    camel.sink.path.channel: general
    camel.component.slack.webhookUrl: webhook_url
EOF
----

If you followed the optional step for secret webhook you can run the following command:

[source,bash,options="nowrap"]
----
oc apply -f config/openshift/slack-sink.yaml
----

Check for messages in your channel

In another terminal, using kafkacat, you should be able to send messages

```
oc exec -i -c kafka my-cluster-kafka-0 -- bin/kafka-console-producer.sh --bootstrap-server localhost:9092 --topic slack-topic
Hello from Apache Camel
```