fix(logger): fallback to distinct-id when user is not set (#4847)

* fix(logger): fallback to distinct-id when user is not set

* Update Changelog

* Update Changelog.md

Author: markushi

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+### Improvements
+
+- Fallback to distinct-id as user.id logging attribute when user is not set ([#4847](https://github.com/getsentry/sentry-java/pull/4847))
+
 ## 8.25.0
 
 ### Fixes

sentry/src/main/java/io/sentry/logger/LoggerApi.java

@@ -270,7 +270,14 @@ private void setServerName(
 
   private void setUser(final @NotNull HashMap<String, SentryLogEventAttributeValue> attributes) {
     final @Nullable User user = scopes.getCombinedScopeView().getUser();
-    if (user != null) {
+    if (user == null) {
+      // In case no user is set, we should fallback to the distinct id, known as installation id,
+      // which is used on Android as default user id
+      final @Nullable String id = scopes.getOptions().getDistinctId();
+      if (id != null) {
+        attributes.put("user.id", new SentryLogEventAttributeValue(SentryAttributeType.STRING, id));
+      }
+    } else {
       final @Nullable String id = user.getId();
       if (id != null) {
         attributes.put("user.id", new SentryLogEventAttributeValue(SentryAttributeType.STRING, id));

sentry/src/test/java/io/sentry/ScopesTest.kt

@@ -2875,7 +2875,11 @@ class ScopesTest {
 
   @Test
   fun `adds user fields to log attributes`() {
-    val (sut, mockClient) = getEnabledScopes { it.logs.isEnabled = true }
+    val (sut, mockClient) =
+      getEnabledScopes {
+        it.logs.isEnabled = true
+        it.distinctId = "distinctId"
+      }
 
     sut.configureScope { scope ->
       scope.user =
@@ -2909,11 +2913,12 @@ class ScopesTest {
   }
 
   @Test
-  fun `missing user does not break attributes`() {
+  fun `unset user does provide distinct-id as user-id`() {
     val (sut, mockClient) =
       getEnabledScopes {
         it.logs.isEnabled = true
         it.isSendDefaultPii = true
+        it.distinctId = "distinctId"
       }
 
     sut.logger().log(SentryLogLevel.WARN, "log message")
@@ -2923,6 +2928,29 @@ class ScopesTest {
         check {
           assertEquals("log message", it.body)
 
+          assertEquals("distinctId", it.attributes?.get("user.id")?.value)
+          assertNull(it.attributes?.get("user.name"))
+          assertNull(it.attributes?.get("user.email"))
+        },
+        anyOrNull(),
+      )
+  }
+
+  @Test
+  fun `unset user does provide null user-id when distinct-id is missing`() {
+    val (sut, mockClient) =
+      getEnabledScopes {
+        it.logs.isEnabled = true
+        it.isSendDefaultPii = true
+        it.distinctId = null
+      }
+
+    sut.logger().log(SentryLogLevel.WARN, "log message")
+
+    verify(mockClient)
+      .captureLog(
+        check {
+          assertEquals("log message", it.body)
           assertNull(it.attributes?.get("user.id"))
           assertNull(it.attributes?.get("user.name"))
           assertNull(it.attributes?.get("user.email"))
@@ -2937,6 +2965,7 @@ class ScopesTest {
       getEnabledScopes {
         it.logs.isEnabled = true
         it.isSendDefaultPii = true
+        it.distinctId = "distinctId"
       }
 
     sut.configureScope { scope -> scope.user = User() }