118 lines
4.0 KiB
Markdown
118 lines
4.0 KiB
Markdown
# Compose sample application
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This sample demonstrates a WebAssembly (Wasm) microservice written in Rust. It subscribes to a Kafka queue topic on a Redpanda server, and then transforms and saves each message into a MySQL (MariaDB) database table. The microservice is compiled into Wasm and runs in the WasmEdge runtime, which is a secure and lightweight alternative to natively compiled Rust apps in Linux containers.
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## Use with Docker Development Environments
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You will need a version of Docker Desktop or Docker CLI with Wasm support.
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* [Install Docker Desktop + Wasm (Beta)](https://docs.docker.com/desktop/wasm/)
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* [Install Docker CLI + Wasm](https://github.com/chris-crone/wasm-day-na-22/tree/main/server)
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## WasmEdge server with Redpanda and MySQL database
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Project structure:
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```
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.
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+-- compose.yml
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|-- etl
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|-- Dockerfile
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|-- Cargo.toml
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+-- src
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|-- main.rs
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|-- kafka
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|-- order.json
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|-- db
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|-- db-password.txt
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```
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The [compose.yml](compose.yml) is as follows.
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```yaml
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services:
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redpanda:
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image: docker.redpanda.com/vectorized/redpanda:v22.2.2
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command:
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- redpanda start
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- --smp 1
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- --overprovisioned
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- --node-id 0
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- --kafka-addr PLAINTEXT://0.0.0.0:29092,OUTSIDE://0.0.0.0:9092
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- --advertise-kafka-addr PLAINTEXT://redpanda:29092,OUTSIDE://redpanda:9092
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- --pandaproxy-addr 0.0.0.0:8082
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- --advertise-pandaproxy-addr localhost:8082
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ports:
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- 8081:8081
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- 8082:8082
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- 9092:9092
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- 9644:9644
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- 29092:29092
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volumes:
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- ./kafka:/app
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etl:
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image: etl-kafka
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build:
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context: etl
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platforms:
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- wasi/wasm32
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environment:
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DATABASE_URL: mysql://root:whalehello@db:3306/mysql
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KAFKA_URL: kafka://redpanda:9092/order
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RUST_BACKTRACE: full
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RUST_LOG: info
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restart: unless-stopped
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runtime: io.containerd.wasmedge.v1
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db:
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image: mariadb:10.9
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environment:
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MYSQL_ROOT_PASSWORD: whalehello
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```
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The compose file defines an application with three services `redpanda`, `etl` and `db`. The `redpanda` service is a Kafka-compatible messaging server that produces messages in a queue topic. The `etl` service, in the WasmEdge container that subscribes to the queue topic and receives incoming messages. Each incoming message is parsed and stored in the `db` MySQL (MariaDB) database server.
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## Deploy with docker compose
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```bash
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$ docker compose up -d
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...
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⠿ Network wasmedge-kafka-mysql_default Created 0.1s
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⠿ Container wasmedge-kafka-mysql-redpanda-1 Created 0.3s
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⠿ Container wasmedge-kafka-mysql-etl-1 Created 0.3s
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⠿ Container wasmedge-kafka-mysql-db-1 Created 0.3s
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```
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## Expected result
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```bash
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$ docker compose ps
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NAME COMMAND SERVICE STATUS PORTS
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wasmedge-kafka-mysql-db-1 "docker-entrypoint.s…" db running 3306/tcp
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wasmedge-kafka-mysql-etl-1 "kafka.wasm" etl running
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wasmedge-kafka-mysql-redpanda-1 "/entrypoint.sh 'red…" redpanda running 0.0.0.0:8081-8082->8081-8082/tcp, :::8081-8082->8081-8082/tcp, 0.0.0.0:9092->9092/tcp, :::9092->9092/tcp, 0.0.0.0:9644->9644/tcp, :::9644->9644/tcp, 0.0.0.0:29092->29092/tcp, :::29092->29092/tcp
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```
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After the application starts,
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log into the Redpanda container and send a message to the queue topic `order` as follows.
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```bash
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$ docker compose exec redpanda /bin/bash
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redpanda@1add2615774b:/$ cd /app
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redpanda@1add2615774b:/app$ cat order.json | rpk topic produce order
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Produced to partition 0 at offset 0 with timestamp 1667922788523.
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```
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To see the data in the database container, you can use the following commands.
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```bash
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$ docker compose exec db /bin/bash
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root@c97c472db02e:/# mysql -u root -pwhalehello mysql
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mysql> select * from orders;
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... ...
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```
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