Add example application about how to write to Slack using the http-re…

…quest agent (#628)

examples/applications/slack/README.md

@@ -0,0 +1,21 @@
+# Slack channel witer
+
+This sample application shows how to write to a slack channel
+
+Export the slack incoming webhook (token) (iwebhooks are locked to slack apps channels at creation):
+export SLACK_TOKEN="<token>"
+
+## Deploy the LangStream application
+```
+langstream docker run slack -app examples/applications/slack -i examples/instances/kafka-docker.yaml  -s examples/secrets/secrets.yaml
+```
+
+## write
+
+Since the application opens a gateway, we can use the gateway API to send and consume messages using the use gateway `chat` feature:
+```
+langstream gateway produce slack produce-input -p sessionId=$(uuidgen) -v "hello"
+```
+
+This is currently working because the slack message and token are hardcoded and need to be referenced by variables.
+

examples/applications/slack/configuration.yaml

@@ -0,0 +1,22 @@
+#
+#
+# Copyright DataStax, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+configuration:
+  defaults:
+    globals:
+      slack:
+        url: "https://hooks.slack.com/services/"

examples/applications/slack/gateways.yaml

@@ -0,0 +1,27 @@
+#
+#
+# Copyright DataStax, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+gateways:
+  - id: produce-input
+    type: produce
+    topic: input-topic
+    parameters:
+      - sessionId
+    produce-options:
+      headers:
+        - key: langstream-client-session-id
+          value-from-parameters: sessionId        

examples/applications/slack/pipeline.yaml

@@ -0,0 +1,32 @@
+#
+# Copyright DataStax, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+topics:
+  - name: "input-topic"
+    creation-mode: create-if-not-exists
+pipeline:
+  - name: "convert-to-json"
+    type: "document-to-json"
+    input: "input-topic"
+    configuration:
+      text-field: "text"
+  - name: "submit to slack API"
+    type: "http-request"
+    configuration:
+      url: "${globals.slack.url}${secrets.slack.token}"
+      body: '{"text":"{{ value.text }}"}'
+      output-field: "value.response"
+      method: "POST"

examples/secrets/secrets.yaml

@@ -123,4 +123,12 @@ secrets:
       access-key: "${BEDROCK_ACCESS_KEY}"
       secret-key: "${BEDROCK_SECRET_KEY}"
       region: "${REGION:-us-east-1}"
-      completions-model: "${BEDROCK_COMPLETIONS_MODEL}"
+      completions-model: "${BEDROCK_COMPLETIONS_MODEL}"
+  - id: slack 
+    data:
+      token: "${SLACK_TOKEN:-}"
+      url: "${SLACK_URL:-}"
+      provider: "${SLACK_PROVIDER:-slack}"
+#      embeddings-model: "${OPEN_AI_EMBEDDINGS_MODEL:-text-embedding-ada-002}"
+#      chat-completions-model: "${OPEN_AI_CHAT_COMPLETIONS_MODEL:-gpt-3.5-turbo}"
+#      text-completions-model: "${OPEN_AI_TEXT_COMPLETIONS_MODEL:-gpt-3.5-turbo-instruct}"