log configuration corner cases

Author: SylvainJuge

jmx-scraper/src/main/java/io/opentelemetry/contrib/jmxscraper/JmxScraper.java

@@ -48,6 +48,9 @@ public class JmxScraper {
   @SuppressWarnings({"SystemOut", "SystemExitOutsideMain"})
   public static void main(String[] args) {
 
+    // set log format
+    System.setProperty("java.util.logging.SimpleFormatter.format", "%1$tFT%1$tT.%1$tL%1$tz | %4$s: %5$s%n");
+
     try {
       Properties argsConfig = parseArgs(Arrays.asList(args));
       propagateToSystemProperties(argsConfig);

jmx-scraper/src/main/java/io/opentelemetry/contrib/jmxscraper/config/PropertiesCustomizer.java

@@ -5,18 +5,21 @@
 
 package io.opentelemetry.contrib.jmxscraper.config;
 
+import static io.opentelemetry.contrib.jmxscraper.config.JmxScraperConfig.JMX_INTERVAL_LEGACY;
+import static io.opentelemetry.contrib.jmxscraper.config.JmxScraperConfig.METRIC_EXPORT_INTERVAL;
+
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.logging.Logger;
 import javax.annotation.Nullable;
 
-import static io.opentelemetry.contrib.jmxscraper.config.JmxScraperConfig.JMX_INTERVAL_LEGACY;
-import static io.opentelemetry.contrib.jmxscraper.config.JmxScraperConfig.METRIC_EXPORT_INTERVAL;
-
 /** Customizer of default SDK configuration and provider of effective scraper config */
 public class PropertiesCustomizer implements Function<ConfigProperties, Map<String, String>> {
 
+  private static final Logger logger = Logger.getLogger(PropertiesCustomizer.class.getName());
+
   private static final String METRICS_EXPORTER = "otel.metrics.exporter";
 
   @Nullable private JmxScraperConfig scraperConfig;
@@ -27,14 +30,15 @@ public Map<String, String> apply(ConfigProperties config) {
 
     // set default exporter to logging when not explicitly set
     if (config.getList(METRICS_EXPORTER).isEmpty()) {
-      // TODO: log (info) this
+      logger.info(METRICS_EXPORTER + " is not set, default of 'logging' will be used");
       result.put(METRICS_EXPORTER, "logging");
     }
 
     // providing compatibility with the existing 'otel.jmx.interval.milliseconds' config option
     long intervalLegacy = config.getLong(JMX_INTERVAL_LEGACY, -1);
     if (config.getDuration(METRIC_EXPORT_INTERVAL) == null && intervalLegacy > 0) {
-      // TODO: log (warn) this
+      logger.warning(METRIC_EXPORT_INTERVAL + " deprecated option is used, replacing with '"
+          + METRIC_EXPORT_INTERVAL + "' metric sdk configuration is recommended");
       result.put(METRIC_EXPORT_INTERVAL, intervalLegacy + "ms");
     }