[Enhance](cdc) Add support for environment variable resolution in parameter mapping

Author: buu-nguyen

flink-doris-connector/src/main/java/org/apache/doris/flink/tools/cdc/CdcTools.java

@@ -38,6 +38,8 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /** cdc sync tools. */
 public class CdcTools {
@@ -221,7 +223,31 @@ public static Map<String, String> getConfigMap(MultipleParameterTool params, Str
         for (String param : params.getMultiParameter(key)) {
             String[] kv = param.split("=", 2);
             if (kv.length == 2) {
-                map.put(kv[0].trim(), kv[1].trim());
+                String originalValue = kv[1].trim();
+                String resolvedValue = originalValue;
+
+                // Regex to find environment variables like $VAR or ${VAR}
+                Pattern pattern = Pattern.compile("\\$(?:([A-Za-z_][A-Za-z0-9_]*)|\\{([A-Za-z_][A-Za-z0-9_]*)\\})");
+                Matcher matcher = pattern.matcher(originalValue);
+                StringBuffer sb = new StringBuffer();
+                boolean varFound = false;
+                while (matcher.find()) {
+                    varFound = true;
+                    String varName = matcher.group(1) != null ? matcher.group(1) : matcher.group(2);
+                    String envValue = System.getenv(varName);
+                    if (envValue != null) {
+                        // Replace with environment variable value
+                        matcher.appendReplacement(sb, Matcher.quoteReplacement(envValue));
+                    } else {
+                        // If environment variable is not found, keep the original placeholder
+                        matcher.appendReplacement(sb, Matcher.quoteReplacement(matcher.group(0)));
+                    }
+                }
+                if (varFound) {
+                    matcher.appendTail(sb);
+                    resolvedValue = sb.toString();
+                }
+                map.put(kv[0].trim(), resolvedValue);
                 continue;
             } else if (kv.length == 1 && EMPTY_KEYS.contains(kv[0])) {
                 map.put(kv[0].trim(), "");

flink-doris-connector/src/test/java/org/apache/doris/flink/tools/cdc/CdcToolsTest.java

@@ -115,4 +115,91 @@ private void assertEquals(
             Assert.assertTrue(valueConf.contains(value));
         }
     }
+
+    @Test
+    public void testGetConfigMapWithEnvironmentVariables() {
+        // Test cases for environment variable substitution.
+        // We assume these environment variables are NOT set in the test environment,
+        // so they should resolve to their placeholder strings.
+
+        // Case 1: Simple env var placeholder
+        MultipleParameterTool params1 =
+                MultipleParameterTool.fromArgs(
+                        new String[] {"--test-conf", "db.user=$DB_USER_UNSET"});
+        Map<String, String> expected1 = new HashMap<>();
+        expected1.put("db.user", "$DB_USER_UNSET");
+        Assert.assertEquals(
+                expected1, CdcTools.getConfigMap(params1, "test-conf"));
+
+        // Case 2: Env var with braces placeholder
+        MultipleParameterTool params2 =
+                MultipleParameterTool.fromArgs(
+                        new String[] {"--test-conf", "db.pass=${DB_PASS_UNSET}"});
+        Map<String, String> expected2 = new HashMap<>();
+        expected2.put("db.pass", "${DB_PASS_UNSET}");
+        Assert.assertEquals(
+                expected2, CdcTools.getConfigMap(params2, "test-conf"));
+
+        // Case 3: Mix of plain string and env var placeholder
+        MultipleParameterTool params3 =
+                MultipleParameterTool.fromArgs(
+                        new String[] {
+                            "--test-conf", "db.host=localhost", "--test-conf", "db.port=$DB_PORT_UNSET"
+                        });
+        Map<String, String> expected3 = new HashMap<>();
+        expected3.put("db.host", "localhost");
+        expected3.put("db.port", "$DB_PORT_UNSET");
+        Assert.assertEquals(
+                expected3, CdcTools.getConfigMap(params3, "test-conf"));
+
+        // Case 4: Env var within a string
+        MultipleParameterTool params4 =
+                MultipleParameterTool.fromArgs(
+                        new String[] {
+                            "--test-conf", "conn.string=jdbc:mysql://$DB_HOST_UNSET:3306/mydb"
+                        });
+        Map<String, String> expected4 = new HashMap<>();
+        expected4.put("conn.string", "jdbc:mysql://$DB_HOST_UNSET:3306/mydb");
+        Assert.assertEquals(
+                expected4, CdcTools.getConfigMap(params4, "test-conf"));
+
+        // Case 5: Multiple env vars in one string
+        MultipleParameterTool params5 =
+                MultipleParameterTool.fromArgs(
+                        new String[] {"--test-conf", "credentials=user:$USER_UNSET,pass:$PASS_UNSET"});
+        Map<String, String> expected5 = new HashMap<>();
+        expected5.put("credentials", "user:$USER_UNSET,pass:$PASS_UNSET");
+        Assert.assertEquals(
+                expected5, CdcTools.getConfigMap(params5, "test-conf"));
+
+        // Case 6: No env vars (regular behavior)
+        MultipleParameterTool params6 =
+                MultipleParameterTool.fromArgs(
+                        new String[] {"--test-conf", "key1=value1", "--test-conf", "key2=value2"});
+        Map<String, String> expected6 = new HashMap<>();
+        expected6.put("key1", "value1");
+        expected6.put("key2", "value2");
+        Assert.assertEquals(
+                expected6, CdcTools.getConfigMap(params6, "test-conf"));
+
+        // Case 7: Env var for a key that allows empty value (e.g. password), resolves to placeholder
+        MultipleParameterTool params7 =
+                MultipleParameterTool.fromArgs(
+                        new String[] {"--test-conf", "password=$PASSWORD_UNSET"});
+        Map<String, String> expected7 = new HashMap<>();
+        expected7.put("password", "$PASSWORD_UNSET"); // DatabaseSyncConfig.PASSWORD is in EMPTY_KEYS
+        Assert.assertEquals(
+                expected7, CdcTools.getConfigMap(params7, "test-conf"));
+
+        // Case 8: Env var that resolves to an empty string (if it were set to empty)
+        // For this test, we simulate it by having the placeholder itself, as we can't set it to empty easily here.
+        // If $EMPTY_VAR was set to "", the result for "key" would be "".
+        // Since it's not set, it remains "$EMPTY_VAR".
+        MultipleParameterTool params8 =
+                MultipleParameterTool.fromArgs(new String[] {"--test-conf", "key=$EMPTY_VAR"});
+        Map<String, String> expected8 = new HashMap<>();
+        expected8.put("key", "$EMPTY_VAR");
+        Assert.assertEquals(
+                expected8, CdcTools.getConfigMap(params8, "test-conf"));
+    }
 }