fix: add default values for environment variables

Author: ludomikula

server/api-service/lowcoder-domain/src/main/java/org/lowcoder/domain/serversetting/service/ServerSettingServiceImpl.java

@@ -1,21 +1,29 @@
 package org.lowcoder.domain.serversetting.service;
 
+import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.StringUtils;
 import org.lowcoder.domain.serversetting.model.ServerSetting;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.core.env.*;
 import org.springframework.stereotype.Service;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 import javax.annotation.PostConstruct;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
 
 
+@RequiredArgsConstructor
 @Slf4j
 @Service
 public class ServerSettingServiceImpl implements ServerSettingService {
+
+    private final Environment environment;
     private final ServerSettingRepository repository;
+
     private final List<String> EXCLUDED_KEYS = List.of("LOWCODER_MONGODB_EXPOSED",
     "LOWCODER_PUID",
     "LOWCODER_PGID",
@@ -33,21 +41,25 @@ public class ServerSettingServiceImpl implements ServerSettingService {
     "LOWCODER_NODE_SERVICE_SECRET",
     "LOWCODER_NODE_SERVICE_SECRET_SALT");
 
-    @Autowired
-    public ServerSettingServiceImpl(ServerSettingRepository repository) {
-        this.repository = repository;
-    }
-
     @Override
     public Mono<Map<String, String>> getServerSettingsMap() {
         return repository.findAll().collectMap(ServerSetting::getKey, ServerSetting::getValue);
     }
 
     @PostConstruct
     public void saveEnvironmentVariables() {
-        Map<String, String> envVariables = System.getenv();
-        Flux.fromIterable(envVariables.keySet())
-                .filter(key -> key.startsWith("LOWCODER_"))
+
+        Map<String, String> defaults = getEnvironmentVariablesDefaults();
+
+        Map<String, String> envVariables = new TreeMap<>(System.getenv().entrySet().stream()
+                .filter(entry -> StringUtils.startsWith(entry.getKey(), "LOWCODER_"))
+                .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)));
+
+        Map<String, String> merged = new TreeMap<>(defaults);
+        merged.keySet().removeAll(envVariables.keySet());
+        merged.putAll(envVariables);
+
+        Flux.fromIterable(merged.keySet())
                 .map(key -> {
                     String value = envVariables.getOrDefault(key, "");
                     if(EXCLUDED_KEYS.contains(key)) {
@@ -61,4 +73,30 @@ public void saveEnvironmentVariables() {
                 .flatMap(repository::save)
                 .subscribe();
     }
+
+
+    private Map<String, String> getEnvironmentVariablesDefaults() {
+        Map<String, String> defaults = new HashMap<>();
+
+        MutablePropertySources propertySources = ((AbstractEnvironment) environment).getPropertySources();
+        StreamSupport.stream(propertySources.spliterator(), false)
+            .filter(EnumerablePropertySource.class::isInstance)
+            .map(EnumerablePropertySource.class::cast)
+            .forEach(propertySource -> {
+                String[] names = propertySource.getPropertyNames();
+                if (names.length > 0) {
+                    Arrays.stream(names).forEach(name -> {
+                        String rawValue = Objects.toString(propertySource.getProperty(name), "");
+                        if (rawValue != null && StringUtils.contains(rawValue, "${LOWCODER_")) {
+                            String defaultValue = StringUtils.substringBetween(rawValue, "${", "}");
+                            String[] keyValue = StringUtils.split(defaultValue, ":");
+                            if (keyValue.length == 2 && !defaults.containsKey(keyValue[0])) {
+                                defaults.put(keyValue[0], keyValue[1]);
+                            }
+                        }
+                    });
+                }
+            });
+        return defaults;
+    }
 }