Fix Azure Managed Identity configuration for SQL authentication in mi-azuresql-spring demo

.gitignore

@@ -58,3 +58,6 @@ build/
 .vscode/
 
 /logs/
+
+# Maven shade plugin artifacts
+dependency-reduced-pom.xml

mi-sql-public-demo/src/main/java/com/example/MainSQL.java

@@ -30,6 +30,10 @@ public static void main(String[] args) {
         String connString = properties.getProperty("AZURE_SQLDB_CONNECTIONSTRING");
         String clientId = properties.getProperty("AZURE_CLIENT_ID");
 
+        // Resolve environment variables in the connection string
+        connString = resolveEnvironmentVariables(connString);
+        clientId = resolveEnvironmentVariables(clientId);
+
         connString = connString + ";msiClientId=" + clientId + ";authentication=ActiveDirectoryMSI";
         System.out.print(connString);
 
@@ -42,5 +46,29 @@ public static void main(String[] args) {
         }
     }
 
+    /**
+     * Resolves environment variables in the format ${VAR_NAME} with their actual values
+     */
+    private static String resolveEnvironmentVariables(String input) {
+        if (input == null) {
+            return null;
+        }
+
+        String result = input;
+        // Find all environment variable references like ${VAR_NAME}
+        java.util.regex.Pattern pattern = java.util.regex.Pattern.compile("\\$\\{([^}]+)\\}");
+        java.util.regex.Matcher matcher = pattern.matcher(result);
+
+        while (matcher.find()) {
+            String varName = matcher.group(1);
+            String envValue = System.getenv(varName);
+            if (envValue != null) {
+                result = result.replace("${" + varName + "}", envValue);
+            }
+        }
+
+        return result;
+    }
+
 
 }

mi-sql-public-demo/src/main/resources/application.properties

@@ -1,5 +1,5 @@
 AZURE_SQLDB_CONNECTIONSTRING=jdbc:sqlserver://${AZ_DATABASE_SERVER_NAME}.database.windows.net:1433;database=demo;encrypt=true;trustServerCertificate=false;hostNameInCertificate=*.database.windows.net;loginTimeout=30;
-AZURE_CLIENT_ID=<your managed identity client id>
+AZURE_CLIENT_ID=${AZURE_CLIENT_ID}
 
 # Enable Azure managed identity for Spring Cloud Azure
 spring.cloud.azure.credential.managed-identity-enabled=true