[GitHub] [druid] clintropolis commented on a change in pull request #9320: fix protobuf extension packaging and docs

[GitBox <gi...@apache.org>]

clintropolis commented on a change in pull request #9320: fix protobuf extension packaging and docs
URL: https://github.com/apache/druid/pull/9320#discussion_r376088414
 
 

 ##########
 File path: docs/development/extensions-core/protobuf.md
 ##########
 @@ -165,54 +164,74 @@ Please make sure these keys are properly configured for successful ingestion.
 }
 ```
 
-## Kafka Producer
+## Adding Protobuf messages to Kafka
 
-Here is the sample script that publishes the metrics to Kafka in Protobuf format.
+If necessary, from your Kafka installation directory run the following command to create the Kafka topic
 
-1. Run `protoc` again with the Python binding option.  This command generates `metrics_pb2.py` file.
- ```
-  protoc -o metrics.desc metrics.proto --python_out=.
- ```
+```
+./bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic metrics_pb
+```
 
-2. Create Kafka producer script.
+This example script requires `protobuf` and `kafka-python` modules. With the topic in place, messages can be inserted running the following command from your Druid installation directory
 
-This script requires `protobuf` and `kafka-python` modules.
+```
+./bin/generate-example-metrics | ./quickstart/protobuf/pb_publisher.py
+```
 
-```python
-#!/usr/bin/env python
+You can confirm that data has been inserted to your Kafka topic using the following command from your Kafka installation directory
+
+```
+./bin/kafka-console-consumer --zookeeper localhost --topic metrics_pb
+```
+
+which should print messages like this
+
+```
+millisecondsGETR"2017-04-06T03:23:56Z*2002/list:request/latencyBwww1.example.com
+```
+
+If your supervisor created in the previous step is running, the indexing tasks should begin producing the messages and the data will soon be available for querying in Druid.
+
+## Generating the example files
+
+The files provided in the example quickstart can be generated in the following manner starting with only `metrics.proto`.
+
+### `metrics.desc`
+
+The descriptor file is generated using `protoc` Protobuf compiler. Given a `.proto` file, a `.desc` file can be generated like so.
+
+```
+protoc -o metrics.desc metrics.proto
+```
+
+### `metrics_pb2.py`
+`metrics_pb2.py` is also generated with `protoc`
+
+```
+ protoc -o metrics.desc metrics.proto --python_out=.
+```
 
+### `pb_publisher.py`
+After `metrics_pb2.py` is generated, another script can be constructed to parse JSON data, convert it to Protobuf, and produce to a Kafka topic
+
+```python
 
 Review comment:
   Oops, accidentally left that off when i moved stuff around :+1:

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