First commit !

.gitignore

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+Thumbs.db
+.DS_Store
+.gradle
+build/
+target/
+out/
+.micronaut/
+.idea
+*.iml
+*.ipr
+*.iws
+.project
+.settings
+.classpath
+.factorypath

README.md

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+## What this is about
+
+This is an exporter for Prometheus to be able to scrape metrics from Shelly (https://shelly.cloud/) modules.
+
+## Why yet-another app doing this
+
+Well, you may be right. But...
+
+First, I wanted to try Micronaut Native for a while, this was a pretty good pretext.
+
+Then, I wanted this to be stateless and config-less. That is, I wanted the full configuration to be in Prometheus and nothing here.
+
+Finally, because I decided so.
+
+## Why java ? this is old/slow/...
+
+Have you actually been trying "modern" java ? That is java (and frameworks) not from previous century ?
+
+## How to use
+
+First, run this application:
+* Either by downloading the native executable (see releases page) and starting it
+* Or by using the docker image: `docker run -d -p 8080:8080 cambierr/shelly-exporter`
+
+Then, in your prometheus config file, add a scrape job:
+
+```yaml
+scrape_configs:
+  # ... your existing jobs
+  - job_name: 'shelly'
+    metrics_path: /metrics
+    static_configs:
+      - targets:
+          - 127.0.0.1:8080 # This is where shelly-exporter is listening
+    scrape_interval: 60s
+    params:
+      host: ["192.168.0.13"] # This is the shelly module hostname
+      type: ["em"] # This is the shelly module type
+      username: ["some-username"] # optional, only if configured on your shelly module
+      password: ["some-password"] # optional, only if configured on your shelly module
+```
+
+## How to build
+
+* `mvn package` will build you an executable jar
+* `mvn package -Dpackaging=native-image` will build you a native executable (assuming you have graal available on your machine)
+* `mvn package -Dpackaging=docker-native` will build you a docker image containing the native executable
+
+## Supported Shelly modules
+
+* Shelly EM
+
+Not a lot, heh ? Feel free to send a PR with the implementation of a new module, or open an issue with the response of the `/status` call of your module :-)
+
+## How to add support for a module
+
+Just create a new class in the `be.romaincambier.shellyexporter.shelly.modules` package, extend the `Shelly` abstract class, and do your thing.

docker-compose.yaml

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+version: '3.7'
+
+services:
+  prometheus:
+    image: prom/prometheus:v2.40.1
+    volumes:
+      - ./prometheus.yml:/etc/prometheus/prometheus.yml
+    command:
+      - '--config.file=/etc/prometheus/prometheus.yml'
+    network_mode: host

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>be.romaincambier</groupId>
+    <artifactId>shelly-exporter</artifactId>
+    <version>0.1</version>
+    <packaging>${packaging}</packaging>
+
+    <parent>
+        <groupId>io.micronaut</groupId>
+        <artifactId>micronaut-parent</artifactId>
+        <version>3.7.3</version>
+    </parent>
+
+    <properties>
+        <packaging>jar</packaging>
+        <jdk.version>17</jdk.version>
+        <release.version>17</release.version>
+        <micronaut.version>3.7.3</micronaut.version>
+        <micronaut.runtime>netty</micronaut.runtime>
+        <exec.mainClass>be.romaincambier.shellyexporter.Application</exec.mainClass>
+    </properties>
+
+    <repositories>
+        <repository>
+            <id>central</id>
+            <url>https://repo.maven.apache.org/maven2</url>
+        </repository>
+    </repositories>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.micronaut</groupId>
+            <artifactId>micronaut-inject</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micronaut</groupId>
+            <artifactId>micronaut-validation</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micronaut</groupId>
+            <artifactId>micronaut-http-client</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micronaut</groupId>
+            <artifactId>micronaut-http-server-netty</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micronaut</groupId>
+            <artifactId>micronaut-jackson-databind</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>jakarta.annotation</groupId>
+            <artifactId>jakarta.annotation-api</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>io.micronaut.build</groupId>
+                <artifactId>micronaut-maven-plugin</artifactId>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <!-- Uncomment to enable incremental compilation -->
+                    <!-- <useIncrementalCompilation>false</useIncrementalCompilation> -->
+
+                    <annotationProcessorPaths combine.self="override">
+                        <path>
+                            <groupId>org.projectlombok</groupId>
+                            <artifactId>lombok</artifactId>
+                            <version>${lombok.version}</version>
+                        </path>
+                        <path>
+                            <groupId>io.micronaut</groupId>
+                            <artifactId>micronaut-inject-java</artifactId>
+                            <version>${micronaut.version}</version>
+                        </path>
+                        <path>
+                            <groupId>io.micronaut</groupId>
+                            <artifactId>micronaut-graal</artifactId>
+                            <version>${micronaut.version}</version>
+                        </path>
+                        <path>
+                            <groupId>io.micronaut</groupId>
+                            <artifactId>micronaut-http-validation</artifactId>
+                            <version>${micronaut.version}</version>
+                        </path>
+                        <path>
+                            <groupId>io.micronaut</groupId>
+                            <artifactId>micronaut-validation</artifactId>
+                            <version>${micronaut.version}</version>
+                        </path>
+                    </annotationProcessorPaths>
+                    <compilerArgs>
+                        <arg>-Amicronaut.processing.group=be.romaincambier</arg>
+                        <arg>-Amicronaut.processing.module=shelly-exporter</arg>
+                    </compilerArgs>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

prometheus.yml

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+scrape_configs:
+  - job_name: 'shelly'
+    metrics_path: /metrics
+    static_configs:
+      - targets:
+          - 127.0.0.1:8080
+    scrape_interval: 60s
+    params:
+      host: ["192.168.0.13"]
+      type: ["em"]

src/main/java/be/romaincambier/shellyexporter/Application.java

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+package be.romaincambier.shellyexporter;
+
+import io.micronaut.runtime.Micronaut;
+
+public class Application {
+    public static void main(String[] args) {
+        Micronaut.build(args)
+                 .eagerInitSingletons(true)
+                 .mainClass(Application.class)
+                 .start();
+    }
+}

src/main/java/be/romaincambier/shellyexporter/prometheus/PrometheusController.java

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+package be.romaincambier.shellyexporter.prometheus;
+
+import be.romaincambier.shellyexporter.shelly.Registry;
+import be.romaincambier.shellyexporter.shelly.Shelly;
+import io.micronaut.http.MediaType;
+import io.micronaut.http.annotation.Controller;
+import io.micronaut.http.annotation.Get;
+import io.micronaut.http.annotation.QueryValue;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.Optional;
+
+@Controller("/metrics")
+@RequiredArgsConstructor
+@Slf4j
+public class PrometheusController {
+
+    private final Registry registry;
+
+    @Get(uri = "/", produces = MediaType.TEXT_PLAIN)
+    public String scrape(
+            @QueryValue("type") String type,
+            @QueryValue("host") String host,
+            @QueryValue(value = "username", defaultValue = "") String username,
+            @QueryValue(value = "password", defaultValue = "") String password) {
+
+        if (type == null || type.isBlank()) {
+            log.warn("Invalid value for type: '{}'", type);
+            return "";
+        }
+
+        if (host == null || host.isBlank()) {
+            log.warn("Invalid value for host: '{}'", host);
+            return "";
+        }
+
+        Optional<Shelly> scraperMaybe = registry.forName(type);
+
+        if (scraperMaybe.isEmpty()) {
+            log.warn("No such shelly scraper: {}", type);
+            return "";
+        }
+
+        return scraperMaybe.get().scrape(host, username, password);
+    }
+
+}

src/main/java/be/romaincambier/shellyexporter/shelly/Registry.java

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+package be.romaincambier.shellyexporter.shelly;
+
+import jakarta.inject.Singleton;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+@Singleton
+public class Registry {
+
+    private final Map<String, Shelly> modules = new HashMap<>();
+
+    public void register(Shelly shelly, String name) {
+        modules.put(name, shelly);
+    }
+
+    public Optional<Shelly> forName(String name) {
+        return Optional.ofNullable(modules.get(name));
+    }
+}

src/main/java/be/romaincambier/shellyexporter/shelly/Shelly.java

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+package be.romaincambier.shellyexporter.shelly;
+
+public abstract class Shelly {
+
+    protected Shelly(Registry registry) {
+        registry.register(this, getName());
+    }
+
+    protected abstract String getName();
+
+    public abstract String scrape(String host, String username, String password);
+}