From a76ebc123b44c9443e84885a0f55b55515c7647b Mon Sep 17 00:00:00 2001
From: sarankumar1325 <120080287+sarankumar1325@users.noreply.github.com>
Date: Sat, 31 Oct 2026 16:32:07 +0000
Subject: [PATCH] fix: base64-encode "." and ".." in Pushgateway URL path
 segments

A job name or grouping key value of "." or ".." was appended to the URL
as is, and URI.normalize() then removed it as a dot segment. For job "j"
with grouping key {instance=".."} the request went to /metrics/job/j/,
and with {instance="."} to /metrics/job/j/instance/, so the push or
delete never reaches the intended group. Base64-encode these values, as
client_golang does.

Signed-off-by: sarankumar1325 <120080287+sarankumar1325@users.noreply.github.com>
---
 .../exporter/pushgateway/PushGateway.java     | 10 ++++++++--
 .../exporter/pushgateway/PushGatewayTest.java | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/prometheus-metrics-exporter-pushgateway/src/main/java/io/prometheus/metrics/exporter/pushgateway/PushGateway.java b/prometheus-metrics-exporter-pushgateway/src/main/java/io/prometheus/metrics/exporter/pushgateway/PushGateway.java
index b7dd844ec3..5c5cef3092 100644
--- a/prometheus-metrics-exporter-pushgateway/src/main/java/io/prometheus/metrics/exporter/pushgateway/PushGateway.java
+++ b/prometheus-metrics-exporter-pushgateway/src/main/java/io/prometheus/metrics/exporter/pushgateway/PushGateway.java
@@ -508,7 +508,7 @@ private URL makeUrl(@Nullable ExporterPushgatewayProperties properties)
       StringBuilder url =
           new StringBuilder(getScheme(properties) + "://" + getAddress(properties) + "/metrics/");
       String job = getJob(properties);
-      if (job.contains("/")) {
+      if (needsBase64(job)) {
         url.append("job@base64/").append(base64url(job));
       } else {
         url.append("job/").append(URLEncoder.encode(job, "UTF-8"));
@@ -518,7 +518,7 @@ private URL makeUrl(@Nullable ExporterPushgatewayProperties properties)
           url.append("/")
               .append(escapeName(entry.getKey(), EscapingScheme.VALUE_ENCODING_ESCAPING))
               .append("@base64/=");
-        } else if (entry.getValue().contains("/")) {
+        } else if (needsBase64(entry.getValue())) {
           url.append("/")
               .append(escapeName(entry.getKey(), EscapingScheme.VALUE_ENCODING_ESCAPING))
               .append("@base64/")
@@ -533,6 +533,12 @@ private URL makeUrl(@Nullable ExporterPushgatewayProperties properties)
       return URI.create(url.toString()).normalize().toURL();
     }
 
+    // "/" would split the value into several path segments, and "." and ".." are dot segments
+    // that normalize() would remove from the path, sending the request to a different group.
+    private boolean needsBase64(String v) {
+      return v.contains("/") || v.equals(".") || v.equals("..");
+    }
+
     private String base64url(String v) {
       return Base64.getEncoder()
           .encodeToString(v.getBytes(StandardCharsets.UTF_8))
diff --git a/prometheus-metrics-exporter-pushgateway/src/test/java/io/prometheus/metrics/exporter/pushgateway/PushGatewayTest.java b/prometheus-metrics-exporter-pushgateway/src/test/java/io/prometheus/metrics/exporter/pushgateway/PushGatewayTest.java
index 8c33543f95..a2296db7c0 100644
--- a/prometheus-metrics-exporter-pushgateway/src/test/java/io/prometheus/metrics/exporter/pushgateway/PushGatewayTest.java
+++ b/prometheus-metrics-exporter-pushgateway/src/test/java/io/prometheus/metrics/exporter/pushgateway/PushGatewayTest.java
@@ -232,6 +232,25 @@ void testPushWithGroupingKeyWithSlashes() throws IOException {
     pg.push();
   }
 
+  @Test
+  void testPushWithDotSegmentJobAndGroupingKey() throws IOException {
+    mockServerClient
+        .when(
+            request()
+                .withMethod("PUT")
+                .withPath("/metrics/job@base64/Li4=/l@base64/Lg==/l2@base64/Li4="))
+        .respond(response().withStatusCode(202));
+    PushGateway pg =
+        PushGateway.builder()
+            .address("localhost:" + mockServerClient.getPort())
+            .registry(registry)
+            .job("..")
+            .groupingKey("l", ".")
+            .groupingKey("l2", "..")
+            .build();
+    pg.push();
+  }
+
   @Test
   void testPushCollectorWithGroupingKey() throws IOException {
     mockServerClient