Example with Kubernetes ConfigMap. (#337)

doc/modules/ROOT/pages/config-sources/filesystem-config-source.adoc

@@ -35,14 +35,14 @@ The same mapping rules as defined for environment variables are applied, so the
 
 To use the FileSystem Config Source, add the following to your Maven `pom.xml`:
 
-[source,xml,subs="verbatim,attributes"]
+https://xxx[[source,xml,subs="verbatim,attributes"]
 ----
 <dependency>
     <groupId>io.smallrye.config</groupId>
     <artifactId>smallrye-config-source-file-system</artifactId>
     <version>{version}</version>
 </dependency>
-----
+----]
 
 This Config Source is not automatically registered. This means that you also need to provide your own
 `ConfigSourceProvider` implementation and registration via `ServiceLoader` to use this Config Source like documented in

examples/configmap/.kubernetes/configmap-app.yml

@@ -0,0 +1,57 @@
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: configmap-app
+spec:
+  type: "LoadBalancer"
+  ports:
+    - name: "http"
+      port: 8080
+      targetPort: 8080
+  selector:
+    app: configmap-app
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: configmap-app
+  labels:
+    app: configmap-app
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: configmap-app
+  template:
+    metadata:
+      labels:
+        app: configmap-app
+    spec:
+      containers:
+        - name: configmap-app
+          image: docker-registry:5000/smallrye-config-examples/configmap-app
+          imagePullPolicy: Always
+          ports:
+            - containerPort: 8080
+          env:
+            - name: CONFIG_MAP_DIR_SOURCE
+              value: "/usr/local/apps/config"
+          volumeMounts:
+            - name: configmap-app
+              mountPath: /usr/local/apps/config
+      volumes:
+        - name: configmap-app
+          configMap:
+            name: configmap-app
+      restartPolicy: Always
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: configmap-app
+  labels:
+    app: configmap-app
+data:
+  smallrye.config.example.configmap.foo: something
+  smallrye.config.example.configmap.bar: something-else

examples/configmap/README.adoc

@@ -0,0 +1,76 @@
+= Kubernetes ConfigMap ConfigSource Example
+
+In this example, the `FileSystemConfigSource` is used to access a Kubernetes ConfigMap configuration.
+
+== Setup
+
+Since the `FileSystemConfigSource` is implemented in a separate `SmallRyeConfig` module, it requires an additional
+dependency in the project that wants to read configuration from Kubernetes ConfigMap.
+
+[source,xml,subs="verbatim,attributes"]
+----
+<dependency>
+    <groupId>io.smallrye.config</groupId>
+    <artifactId>smallrye-config-source-file-system</artifactId>
+    <version>{version}</version>
+</dependency>
+----
+
+== Implementation
+
+The `FileSystemConfigSource` needs to be registed with the application. The recommended way is to use a
+`ConfigSourceFactory` via the standard ServiceLoader mechanism. The factory gives the option to configure the
+`FileSystemConfigSource` with higher priority ConfigSources.
+
+[source,java]
+----
+public class ConfigMapConfigSourceFactory implements ConfigSourceFactory {
+    @Override
+    public ConfigSource getSource(final ConfigSourceContext context) {
+        final ConfigValue value = context.getValue("CONFIG_MAP_DIR_SOURCE");
+        if (value == null || value.getValue() == null) {
+            throw new IllegalArgumentException("CONFIG_MAP_DIR_SOURCE not defined");
+        }
+
+        return new FileSystemConfigSource(value.getValue());
+    }
+
+    @Override
+    public OptionalInt getPriority() {
+        return OptionalInt.of(200);
+    }
+}
+----
+
+In this case, the volume path to read the Kubernetes ConfigMap comes from an environment variable configuration.
+
+== Run
+
+The example starts a simple http server with a single endpoint im `/configMap`. To deploy the example in a Kubernetes
+cluster requires the following steps.
+
+Set up a local Docker Registry first to store the generated Docker images:
+
+[source,bash]
+----
+docker run -d -p 5000:5000 --restart=always --name docker-registry registry:2
+----
+
+Set up a host in '/etc/hosts' pointing `127.0.0.1` to `docker-registry`.
+
+Build the example with:
+
+[source,bash]
+----
+mvn package docker:build docker:push
+----
+
+Deploy to Kubernetes with:
+
+[source,bash]
+----
+kubectl apply -f .kubernetes
+----
+
+Call tbe endpoint `curl http://localhost:8080/configMap`. This should list all the configurations set in the Kubernets
+Config Map. The Kubernetes and ConfigMap configuration can be found in `.kubernetes/configmap-app.yml`.

examples/configmap/pom.xml

@@ -0,0 +1,110 @@
+<?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>
+  <parent>
+    <groupId>io.smallrye</groupId>
+    <artifactId>smallrye-parent</artifactId>
+    <version>20</version>
+  </parent>
+
+  <groupId>io.smallrye.config.examples</groupId>
+  <artifactId>configmap</artifactId>
+  <version>1.8.2-SNAPSHOT</version>
+
+  <name>SmallRye Config Examples: ConfigMap</name>
+
+  <dependencies>
+    <dependency>
+      <groupId>jakarta.annotation</groupId>
+      <artifactId>jakarta.annotation-api</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>io.smallrye.config</groupId>
+      <artifactId>smallrye-config</artifactId>
+      <version>${project.version}</version>
+    </dependency>
+
+    <dependency>
+      <groupId>io.smallrye.config</groupId>
+      <artifactId>smallrye-config-source-file-system</artifactId>
+      <version>${project.version}</version>
+    </dependency>
+
+    <!-- Test Dependencies -->
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <artifactId>maven-assembly-plugin</artifactId>
+        <version>3.3.0</version>
+        <configuration>
+          <finalName>${project.artifactId}-app</finalName>
+          <appendAssemblyId>false</appendAssemblyId>
+          <archive>
+            <manifest>
+              <mainClass>io.smallrye.config.examples.configmap.ConfigMapApp</mainClass>
+            </manifest>
+          </archive>
+          <descriptorRefs>
+            <descriptorRef>jar-with-dependencies</descriptorRef>
+          </descriptorRefs>
+        </configuration>
+        <executions>
+          <execution>
+            <id>create-jar</id>
+            <phase>package</phase>
+            <goals>
+              <goal>single</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+
+      <plugin>
+        <groupId>io.fabric8</groupId>
+        <artifactId>docker-maven-plugin</artifactId>
+        <version>0.33.0</version>
+        <configuration>
+          <verbose>true</verbose>
+          <registry>docker-registry:5000</registry>
+          <pullRegistry>docker.io</pullRegistry>
+          <images>
+            <image>
+              <name>smallrye-config-examples/configmap-app</name>
+              <build>
+                <from>adoptopenjdk/openjdk11:alpine-slim</from>
+                <ports>
+                  <port>8080</port>
+                </ports>
+                <workdir>/usr/local/apps</workdir>
+                <assembly>
+                  <name>usr/local/apps</name>
+                  <inline>
+                    <files>
+                      <file>
+                        <source>${project.build.directory}/${project.artifactId}-app.jar</source>
+                        <destName>${project.artifactId}-app.jar</destName>
+                      </file>
+                    </files>
+                  </inline>
+                </assembly>
+                <cmd>java -jar ${project.artifactId}-app.jar</cmd>
+              </build>
+              <run>
+                <ports>
+                  <port>8080:8080</port>
+                </ports>
+              </run>
+            </image>
+          </images>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

examples/configmap/src/main/java/io/smallrye/config/examples/configmap/ConfigMapApp.java

@@ -0,0 +1,44 @@
+package io.smallrye.config.examples.configmap;
+
+import java.net.InetSocketAddress;
+import java.util.Map;
+
+import org.eclipse.microprofile.config.Config;
+import org.eclipse.microprofile.config.ConfigProvider;
+import org.eclipse.microprofile.config.spi.ConfigSource;
+
+import com.sun.net.httpserver.HttpServer;
+
+public class ConfigMapApp {
+    public static void main(String[] args) throws Exception {
+        Config config = ConfigProvider.getConfig();
+
+        HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);
+        server.createContext("/configMap", exchange -> {
+            boolean responseSent = false;
+
+            final Iterable<ConfigSource> configSources = config.getConfigSources();
+            for (ConfigSource configSource : configSources) {
+                if (configSource.getName().startsWith("FileSystemConfig")) {
+                    final Map<String, String> properties = configSource.getProperties();
+                    final byte[] bytes = properties.toString().getBytes();
+                    exchange.sendResponseHeaders(200, properties.toString().length());
+                    exchange.getResponseBody().write(bytes);
+                    exchange.getResponseBody().flush();
+                    exchange.getResponseBody().close();
+                    responseSent = true;
+                    break;
+                }
+            }
+
+            if (!responseSent) {
+                exchange.sendResponseHeaders(404, 0);
+                exchange.getResponseBody().write(new byte[0]);
+                exchange.getResponseBody().flush();
+                exchange.getResponseBody().close();
+            }
+        });
+
+        server.start();
+    }
+}

examples/configmap/src/main/java/io/smallrye/config/examples/configmap/ConfigMapConfigSourceFactory.java

@@ -0,0 +1,27 @@
+package io.smallrye.config.examples.configmap;
+
+import java.util.OptionalInt;
+
+import org.eclipse.microprofile.config.spi.ConfigSource;
+
+import io.smallrye.config.ConfigSourceContext;
+import io.smallrye.config.ConfigSourceFactory;
+import io.smallrye.config.ConfigValue;
+import io.smallrye.config.source.file.FileSystemConfigSource;
+
+public class ConfigMapConfigSourceFactory implements ConfigSourceFactory {
+    @Override
+    public ConfigSource getSource(final ConfigSourceContext context) {
+        final ConfigValue value = context.getValue("config.map.dir.source");
+        if (value == null || value.getValue() == null) {
+            throw new IllegalArgumentException("CONFIG_MAP_DIR_SOURCE not defined");
+        }
+
+        return new FileSystemConfigSource(value.getValue());
+    }
+
+    @Override
+    public OptionalInt getPriority() {
+        return OptionalInt.of(200);
+    }
+}

examples/configmap/src/main/resources/META-INF/services/io.smallrye.config.ConfigSourceFactory

@@ -0,0 +1 @@
+io.smallrye.config.examples.configmap.ConfigMapConfigSourceFactory

examples/pom.xml

@@ -32,5 +32,6 @@
     <module>interceptors</module>
     <module>expansion</module>
     <module>profiles</module>
+    <module>configmap</module>
   </modules>
 </project>

sources/file-system/src/main/java/io/smallrye/config/source/file/FileSystemConfigSource.java

@@ -60,18 +60,22 @@ public class FileSystemConfigSource extends MapBackedConfigSource {
 
     private static final Pattern PATTERN = Pattern.compile("[^a-zA-Z0-9_]");
 
-    FileSystemConfigSource(File dir) {
+    public FileSystemConfigSource(File dir) {
         this(dir, DEFAULT_ORDINAL);
     }
 
+    public FileSystemConfigSource(String dir) {
+        this(new File(dir), DEFAULT_ORDINAL);
+    }
+
     /**
      * Construct a new instance
      *
      * @param dir the directory, containing configuration files
      * @param ordinal the ordinal value
      */
     public FileSystemConfigSource(File dir, int ordinal) {
-        super("DirConfigSource[dir=" + dir.getAbsolutePath() + "]", scan(dir), ordinal);
+        super("FileSystemConfigSource[dir=" + dir.getAbsolutePath() + "]", scan(dir), ordinal);
     }
 
     private static Map<String, String> scan(File directory) {