Add info metric that allows us to track the config

src/main/java/net/ripe/rpki/rsyncit/config/AppConfig.java

@@ -1,23 +1,29 @@
 package net.ripe.rpki.rsyncit.config;
 
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.MeterRegistry;
+import jakarta.annotation.PostConstruct;
 import lombok.Getter;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.actuate.info.Info;
+import org.springframework.boot.actuate.info.InfoContributor;
 import org.springframework.boot.info.GitProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.stereotype.Component;
 
 import java.time.Duration;
+import java.util.Map;
 import java.util.function.Function;
 
 @Component
 @Getter
-public class AppConfig {
+public class AppConfig implements InfoContributor {
 
     private final String rrdpUrl;
     private final String rrdpReplaceHostWith;
     private final String rsyncPath;
     private final String cron;
-    private final String requestTimeout;
+    private final Duration requestTimeout;
     private final ApplicationInfo info;
     private final long targetDirectoryRetentionPeriodMs;
     private final int targetDirectoryRetentionCopiesCount;
@@ -28,12 +34,13 @@ public AppConfig(@Value("${rrdpUrl}") String rrdpUrl,
                      // Run every 10 minutes
                      @Value("${cron:0 0/10 * * * ?}") String cron,
                      // 3 minutes by default
-                     @Value("${requestTimeout:PT180S}") String requestTimeout,
+                     @Value("${requestTimeout:PT180S}") Duration requestTimeout,
                      // delete rsync directories older than 1 hour
                      @Value("${targetDirectoryRetentionPeriodMs:3600000}") long targetDirectoryRetentionPeriodMs,
                      // do not keep more than 8 copies of rsync directories at once
                      @Value("${targetDirectoryRetentionCopiesCount:8}") int targetDirectoryRetentionCopiesCount,
-                     ApplicationInfo info) {
+                     ApplicationInfo info,
+                     MeterRegistry registry) {
         this.rrdpUrl = rrdpUrl;
         this.rrdpReplaceHostWith = rrdpReplaceHostWith;
         this.rsyncPath = rsyncPath;
@@ -42,10 +49,21 @@ public AppConfig(@Value("${rrdpUrl}") String rrdpUrl,
         this.info = info;
         this.targetDirectoryRetentionPeriodMs = targetDirectoryRetentionPeriodMs;
         this.targetDirectoryRetentionCopiesCount = targetDirectoryRetentionCopiesCount;
+
+        Gauge.builder("rsyncit.configuration", () -> 1.0)
+                .baseUnit("info")
+                .tag("rrdp_url", rrdpUrl)
+                .tag("rrdp_override_host", rrdpReplaceHostWith)
+                .tag("request_timeout_seconds", String.valueOf(requestTimeout.toSeconds()))
+                .tag("retention_period_minutes", String.valueOf(Duration.ofMillis(targetDirectoryRetentionPeriodMs).toMinutes()))
+                .tag("retention_copies", String.valueOf(targetDirectoryRetentionCopiesCount))
+                .tag("build", info.gitCommitId())
+                .strongReference(true)
+                .register(registry);
     }
 
     public Config getConfig() {
-        return new Config(rrdpUrl, substitutor(rrdpReplaceHostWith), rsyncPath, cron, Duration.parse(requestTimeout),
+        return new Config(rrdpUrl, substitutor(rrdpReplaceHostWith), rsyncPath, cron, requestTimeout,
             targetDirectoryRetentionPeriodMs, targetDirectoryRetentionCopiesCount);
     }
 
@@ -64,5 +82,17 @@ static Function<String, String> substitutor(String rrdpReplaceHostWith) {
     public static ApplicationInfo appInfo(GitProperties gitProperties) {
         return new ApplicationInfo(gitProperties.getShortCommitId());
     }
-
+    @Override
+    public void contribute(Info.Builder builder) {
+        builder.withDetail("config", Map.of(
+            "cron", cron,
+            "rrdp_url", rrdpUrl,
+            "rrdp_replace_host", rrdpReplaceHostWith,
+            "rsync_path", rsyncPath,
+            "request_timeout_seconds", String.valueOf(requestTimeout.toSeconds()),
+            "retention_period_minutes", String.valueOf(Duration.ofMillis(targetDirectoryRetentionPeriodMs).toMinutes()),
+            "retention_copies", String.valueOf(targetDirectoryRetentionCopiesCount),
+            "build", info.gitCommitId()
+        ));
+    }
 }