Restore Java worker

worker/Dockerfile

@@ -1,11 +1,19 @@
-FROM microsoft/dotnet:1.0.0-preview1
+FROM java:openjdk-8-jdk-alpine
 
-WORKDIR /app
+RUN MAVEN_VERSION=3.3.3 \
+ && cd /usr/share \
+ && wget http://archive.apache.org/dist/maven/maven-3/$MAVEN_VERSION/binaries/apache-maven-$MAVEN_VERSION-bin.tar.gz -O - | tar xzf - \
+ && mv /usr/share/apache-maven-$MAVEN_VERSION /usr/share/maven \
+ && ln -s /usr/share/maven/bin/mvn /usr/bin/mvn
 
-ADD src/ /app/src/
+WORKDIR /code
 
-RUN dotnet restore -v minimal src/ \
-    && dotnet publish -c Release -o ./ src/Worker/ \
-    && rm -rf src/ $HOME/.nuget/
+ADD pom.xml /code/pom.xml
+RUN ["mvn", "dependency:resolve"]
+RUN ["mvn", "verify"]
 
-CMD dotnet Worker.dll
+# Adding source, compile and package into a fat jar
+ADD src /code/src
+RUN ["mvn", "package"]
+
+CMD ["java", "-jar", "target/worker-jar-with-dependencies.jar"]

worker/pom.xml

@@ -0,0 +1,84 @@
+<?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>worker</groupId>
+  <artifactId>worker</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+
+  <dependencies>
+    <dependency>
+      <groupId>org.json</groupId>
+      <artifactId>json</artifactId>
+      <version>20140107</version>
+    </dependency>
+
+    <dependency>
+        <groupId>redis.clients</groupId>
+        <artifactId>jedis</artifactId>
+        <version>2.7.2</version>
+        <type>jar</type>
+        <scope>compile</scope>
+    </dependency>
+
+    <dependency>
+        <groupId>org.postgresql</groupId>
+        <artifactId>postgresql</artifactId>
+        <version>9.4-1200-jdbc41</version>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-jar-plugin</artifactId>
+        <version>2.4</version>
+        <configuration>
+          <finalName>worker</finalName>
+          <archive>
+            <manifest>
+              <addClasspath>true</addClasspath>
+              <mainClass>worker.Worker</mainClass>
+              <classpathPrefix>dependency-jars/</classpathPrefix>
+            </manifest>
+          </archive>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.1</version>
+        <configuration>
+          <source>1.7</source>
+          <target>1.7</target>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-assembly-plugin</artifactId>
+        <executions>
+          <execution>
+            <goals>
+              <goal>attached</goal>
+            </goals>
+            <phase>package</phase>
+            <configuration>
+              <finalName>worker</finalName>
+              <descriptorRefs>
+                <descriptorRef>jar-with-dependencies</descriptorRef>
+              </descriptorRefs>
+              <archive>
+                <manifest>
+                  <mainClass>worker.Worker</mainClass>
+                </manifest>
+              </archive>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

worker/src/main/java/worker/Worker.java

@@ -0,0 +1,101 @@
+package worker;
+
+import redis.clients.jedis.Jedis;
+import redis.clients.jedis.exceptions.JedisConnectionException;
+import java.sql.*;
+import org.json.JSONObject;
+
+class Worker {
+  public static void main(String[] args) {
+    try {
+      Jedis redis = connectToRedis("redis");
+      Connection dbConn = connectToDB("db");
+
+      System.err.println("Watching vote queue");
+
+      while (true) {
+        String voteJSON = redis.blpop(0, "votes").get(1);
+        JSONObject voteData = new JSONObject(voteJSON);
+        String voterID = voteData.getString("voter_id");
+        String vote = voteData.getString("vote");
+
+        System.err.printf("Processing vote for '%s' by '%s'\n", vote, voterID);
+        updateVote(dbConn, voterID, vote);
+      }
+    } catch (SQLException e) {
+      e.printStackTrace();
+      System.exit(1);
+    }
+  }
+
+  static void updateVote(Connection dbConn, String voterID, String vote) throws SQLException {
+    PreparedStatement insert = dbConn.prepareStatement(
+      "INSERT INTO votes (id, vote) VALUES (?, ?)");
+    insert.setString(1, voterID);
+    insert.setString(2, vote);
+
+    try {
+      insert.executeUpdate();
+    } catch (SQLException e) {
+      PreparedStatement update = dbConn.prepareStatement(
+        "UPDATE votes SET vote = ? WHERE id = ?");
+      update.setString(1, vote);
+      update.setString(2, voterID);
+      update.executeUpdate();
+    }
+  }
+
+  static Jedis connectToRedis(String host) {
+    Jedis conn = new Jedis(host);
+
+    while (true) {
+      try {
+        conn.keys("*");
+        break;
+      } catch (JedisConnectionException e) {
+        System.err.println("Failed to connect to redis - retrying");
+        sleep(1000);
+      }
+    }
+
+    System.err.println("Connected to redis");
+    return conn;
+  }
+
+  static Connection connectToDB(String host) throws SQLException {
+    Connection conn = null;
+
+    try {
+
+      Class.forName("org.postgresql.Driver");
+      String url = "jdbc:postgresql://" + host + "/postgres";
+
+      while (conn == null) {
+        try {
+          conn = DriverManager.getConnection(url, "postgres", "");
+        } catch (SQLException e) {
+          System.err.println("Failed to connect to db - retrying");
+          sleep(1000);
+        }
+      }
+
+      PreparedStatement st = conn.prepareStatement(
+        "CREATE TABLE IF NOT EXISTS votes (id VARCHAR(255) NOT NULL UNIQUE, vote VARCHAR(255) NOT NULL)");
+      st.executeUpdate();
+
+    } catch (ClassNotFoundException e) {
+      e.printStackTrace();
+      System.exit(1);
+    }
+
+    return conn;
+  }
+
+  static void sleep(long duration) {
+    try {
+      Thread.sleep(duration);
+    } catch (InterruptedException e) {
+      System.exit(1);
+    }
+  }
+}