Support for reading env from .env files

inject/src/main/java/io/micronaut/context/env/DotEnvPropertySourceLoader.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2017-2025 original authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.micronaut.context.env;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+
+public class DotEnvPropertySourceLoader extends AbstractPropertySourceLoader {
+
+    /**
+     * File extension for property source loader.
+     */
+    public static final String FILE_EXTENSION = "env";
+
+    public DotEnvPropertySourceLoader() {
+    }
+
+    public DotEnvPropertySourceLoader(boolean logEnabled) { super(logEnabled); }
+
+    @Override
+    public Set<String> getExtensions() { return Collections.singleton(FILE_EXTENSION); }
+
+    @Override
+    protected void processInput(String name, InputStream input, Map<String, Object> finalMap) throws IOException {
+        try (BufferedReader reader = new BufferedReader(new InputStreamReader(input))) {
+            String line;
+            while ((line = reader.readLine()) != null) {
+                parseLine(line, finalMap);
+            }
+        }
+    }
+
+    private void parseLine(String line, Map<String, Object> finalMap) {
+        line = line.trim();
+
+        if (line.isEmpty() || line.startsWith("#")) { return; }
+
+        int delimIndex = line.indexOf('=');
+        if (delimIndex <= 0) { return; }
+
+        String key = line.substring(0, delimIndex).trim();
+        String val = line.substring(delimIndex+1).trim();
+
+        if (key.isEmpty() || val.isEmpty()) { return; }
+
+        key = processKey(key);
+        val = processVal(val);
+
+        finalMap.put(key, val);
+    }
+
+    private String processKey(String key) {
+        return key.toLowerCase().replace('_', '.');
+    }
+
+    private String processVal(String val) {
+        if (val.length() >= 2) {
+            if ((val.startsWith("'") && val.endsWith("'")) || (val.startsWith("\"") && val.endsWith("\""))) {
+                return val.substring(1, val.length()-1);
+            }
+        }
+        return val;
+    }
+}

inject/src/main/resources/META-INF/services/io.micronaut.context.env.PropertySourceLoader

@@ -1,2 +1,3 @@
 io.micronaut.context.env.yaml.YamlPropertySourceLoader
 io.micronaut.context.env.PropertiesPropertySourceLoader
+io.micronaut.context.env.DotEnvPropertySourceLoader

inject/src/test/groovy/io/micronaut/context/env/DotEnvPropertySourceLoaderSpec.groovy

@@ -0,0 +1,42 @@
+package io.micronaut.context.env
+
+import io.micronaut.core.io.service.ServiceDefinition
+import io.micronaut.core.io.service.SoftServiceLoader
+import spock.lang.Specification
+
+class DotEnvPropertySourceLoaderSpec extends Specification {
+
+    void "test dot-env property source loader"() {
+        given:
+        def serviceDefinition = Mock(ServiceDefinition)
+        serviceDefinition.isPresent() >> true
+        serviceDefinition.load() >> new DotEnvPropertySourceLoader()
+
+        Environment env = new DefaultEnvironment({ ["test"] }) {
+            @Override
+            protected SoftServiceLoader<PropertySourceLoader> readPropertySourceLoaders() {
+                GroovyClassLoader gcl = new GroovyClassLoader()
+                gcl.addURL(DotEnvPropertySourceLoader.getResource("/META-INF/services/io.micronaut.context.env.PropertySourceLoader"))
+                return new SoftServiceLoader<PropertySourceLoader>(PropertySourceLoader, gcl)
+            }
+
+            @Override
+            Optional<InputStream> getResourceAsStream(String path) {
+                return Optional.of(new ByteArrayInputStream('''\
+HIBERNATE_CACHE_QUERIES=false
+DATASOURCE_POOLED   = true
+DATASOURCE_DRIVER-CLASS-NAME="org.h2.Driver"
+'''.bytes))
+            }
+        }
+
+        when:
+        env.start()
+
+        then:
+        env.get("hibernate.cache.queries", Boolean).get() == false
+        env.get("datasource.pooled", Boolean).get() == true
+        env.get("datasource.driver-class-name", String).get() == 'org.h2.Driver'
+
+    }
+}