62 lines
2.3 KiB
Markdown
62 lines
2.3 KiB
Markdown
# Your first Watermill app
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This example project shows a basic setup of Watermill. The application runs in a loop, consuming events from a Kafka
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topic, modifying them and publishing to another topic.
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There's a docker-compose file included, so you can run the example and see it in action.
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To understand the background and internals, see [getting started guide](https://watermill.io/learn/getting-started/).
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## Files
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- [main.go](main.go) - example source code, the **most interesting file for you**
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- [docker-compose.yml](docker-compose.yml) - local environment Docker Compose configuration, contains Golang, Kafka and Zookeeper
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- [go.mod](go.mod) - Go modules dependencies, you can find more information at [Go wiki](https://github.com/golang/go/wiki/Modules)
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- [go.sum](go.sum) - Go modules checksums
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## Requirements
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To run this example you will need Docker and docker-compose installed. See the [installation guide](https://docs.docker.com/compose/install/).
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## Running
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```bash
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> docker-compose up
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[some initial logs]
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server_1 | 2019/08/29 19:41:23 received event {ID:0}
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server_1 | 2019/08/29 19:41:23 received event {ID:1}
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server_1 | 2019/08/29 19:41:23 received event {ID:2}
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server_1 | 2019/08/29 19:41:23 received event {ID:3}
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server_1 | 2019/08/29 19:41:24 received event {ID:4}
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server_1 | 2019/08/29 19:41:25 received event {ID:5}
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server_1 | 2019/08/29 19:41:26 received event {ID:6}
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server_1 | 2019/08/29 19:41:27 received event {ID:7}
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server_1 | 2019/08/29 19:41:28 received event {ID:8}
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server_1 | 2019/08/29 19:41:29 received event {ID:9}
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```
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Open another terminal and take a look at Kafka topics to see that all messages are there. The initial events should be present on the `events` topic:
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```bash
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> docker-compose exec server mill kafka consume -b kafka:9092 --topic events
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{"id":12}
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{"id":13}
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{"id":14}
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{"id":15}
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{"id":16}
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{"id":17}
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```
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And the processed messages will be stored in the `events-processed` topic:
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```bash
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> docker-compose exec server mill kafka consume -b kafka:9092 -t events-processed
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{"processed_id":21,"time":"2019-08-29T19:42:31.4464598Z"}
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{"processed_id":22,"time":"2019-08-29T19:42:32.4501767Z"}
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{"processed_id":23,"time":"2019-08-29T19:42:33.4530692Z"}
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{"processed_id":24,"time":"2019-08-29T19:42:34.4561694Z"}
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{"processed_id":25,"time":"2019-08-29T19:42:35.4608918Z"}
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```
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