diff --git a/ext/autoload_php_files.c b/ext/autoload_php_files.c
index f51c3aabd5a..23d786c862f 100644
--- a/ext/autoload_php_files.c
+++ b/ext/autoload_php_files.c
@@ -179,6 +179,43 @@ static void dd_load_files(const char *files_file) {
 
 #define dd_load_files(file) EXPECTED(get_global_DD_AUTOLOAD_NO_COMPILE() == false) ? dd_load_file("bridge/_generated_" file) : dd_load_files("bridge/_files_" file)
 
+// Remove mixed return types for PHP 7.4 support. OpenTelemetry v2 now requires ": mixed" and drops PHP 7.4, but we fixup the AST here so that OpenTelemetry v1 still works with PHP 7.4.
+#if PHP_VERSION_ID >= 70400 && PHP_VERSION_ID < 80000
+void dd_walk_ast_top_stmt(zend_ast *ast) {
+    if (ast->kind == ZEND_AST_STMT_LIST) {
+        zend_ast_list *list = zend_ast_get_list(ast);
+        uint32_t i;
+        for (i = 0; i < list->children; ++i) {
+            dd_walk_ast_top_stmt(list->child[i]);
+        }
+    } else if (ast->kind == ZEND_AST_FUNC_DECL || ast->kind == ZEND_AST_METHOD) {
+        zend_ast_decl *decl = (zend_ast_decl *) ast;
+        zend_ast *return_type_ast = decl->child[3];
+        if (return_type_ast && return_type_ast->kind != ZEND_AST_TYPE) {
+            if (zend_string_equals_literal(zend_ast_get_str(return_type_ast), "mixed")) {
+                decl->child[3] = NULL;
+                zend_ast_destroy(return_type_ast);
+            }
+        }
+    } else if (ast->kind == ZEND_AST_CLASS) {
+        zend_ast_decl *decl = (zend_ast_decl *) ast;
+        zend_ast *stmt_ast = decl->child[2];
+
+        dd_walk_ast_top_stmt(stmt_ast);
+    } else if (ast->kind == ZEND_AST_NAMESPACE && ast->child[1]) {
+        dd_walk_ast_top_stmt(ast->child[1]);
+    }
+}
+
+zend_ast_process_t dd_prev_ast_process = NULL;
+void dd_remove_mixed_return(zend_ast *ast) {
+    dd_walk_ast_top_stmt(ast);
+    if (dd_prev_ast_process) {
+        dd_prev_ast_process(ast);
+    }
+}
+#endif
+
 // We have, at this place, the luxury of knowing that we'll always be called before composers autoloader.
 // Note that this code will also be called during opcache.preload, allowing us to not consider that scenario separately.
 // The first time the autoloader gets invoked for ddtrace\\, we load the API
@@ -211,9 +248,16 @@ static zend_class_entry *dd_perform_autoload(zend_string *class_name, zend_strin
             }
         }
 
-        if (get_DD_TRACE_OTEL_ENABLED() && zend_string_starts_with_literal(lc_name, "opentelemetry\\") && !DDTRACE_G(otel_is_loaded)) {
+        if ((get_DD_TRACE_OTEL_ENABLED() || get_DD_METRICS_OTEL_ENABLED()) && zend_string_starts_with_literal(lc_name, "opentelemetry\\") && !DDTRACE_G(otel_is_loaded)) {
             DDTRACE_G(otel_is_loaded) = 1;
+#if PHP_VERSION_ID >= 70400 && PHP_VERSION_ID < 80000
+            dd_prev_ast_process = zend_ast_process;
+            zend_ast_process = dd_remove_mixed_return;
             dd_load_files("opentelemetry");
+            zend_ast_process = dd_prev_ast_process;
+#else
+            dd_load_files("opentelemetry");
+#endif
             if ((ce = zend_hash_find_ptr(EG(class_table), lc_name))) {
                 return ce;
             }
diff --git a/ext/configuration.h b/ext/configuration.h
index e6f471c2f55..784c39c2e7c 100644
--- a/ext/configuration.h
+++ b/ext/configuration.h
@@ -139,6 +139,7 @@ enum ddtrace_sampling_rules_format {
     CONFIG(INT, DD_EXCEPTION_REPLAY_CAPTURE_INTERVAL_SECONDS, "3600")                                          \
     CONFIG(STRING, DD_TRACE_MEMORY_LIMIT, "")                                                                  \
     CONFIG(BOOL, DD_TRACE_REPORT_HOSTNAME, "false")                                                            \
+    CONFIG(STRING, DD_HOSTNAME, "")                                                                            \
     CONFIG(BOOL, DD_TRACE_FLUSH_COLLECT_CYCLES, "false")                                                       \
     CONFIG(BOOL, DD_TRACE_FORCE_FLUSH_ON_SHUTDOWN, "false") /* true if pid == 1 || ppid == 1 */                \
     CONFIG(BOOL, DD_TRACE_FORCE_FLUSH_ON_SIGTERM, "false") /* true if pid == 1 || ppid == 1 */                 \
@@ -227,6 +228,7 @@ enum ddtrace_sampling_rules_format {
     CONFIG(BOOL, DD_TRACE_WORDPRESS_CALLBACKS, "true")                                                         \
     CONFIG(BOOL, DD_INTEGRATION_METRICS_ENABLED, "true",                                                       \
            .env_config_fallback = ddtrace_conf_otel_metrics_exporter)                                          \
+    CONFIG(BOOL, DD_METRICS_OTEL_ENABLED, "false")                                                             \
     CONFIG(BOOL, DD_TRACE_OTEL_ENABLED, "false")                                                               \
     CONFIG(STRING, DD_TRACE_LOG_FILE, "", .ini_change = zai_config_system_ini_change)                          \
     CONFIG(STRING, DD_TRACE_LOG_LEVEL, "error", .ini_change = ddtrace_alter_dd_trace_log_level,                \
diff --git a/ext/serializer.c b/ext/serializer.c
index 51c4e1eac93..35ae7b9d52b 100644
--- a/ext/serializer.c
+++ b/ext/serializer.c
@@ -816,18 +816,25 @@ void ddtrace_set_root_span_properties(ddtrace_root_span_data *span) {
     }
 
     if (get_DD_TRACE_REPORT_HOSTNAME()) {
+        if (ZSTR_LEN(get_DD_HOSTNAME())) {
+            zval hostname_zv;
+            ZVAL_STR(&hostname_zv, get_DD_HOSTNAME());
+            zend_hash_str_add_new(meta, ZEND_STRL("_dd.hostname"), &hostname_zv);
+        } else {
+
 #ifndef HOST_NAME_MAX
 #define HOST_NAME_MAX 255
 #endif
 
-        zend_string *hostname = zend_string_alloc(HOST_NAME_MAX, 0);
-        if (gethostname(ZSTR_VAL(hostname), HOST_NAME_MAX + 1)) {
-            zend_string_release(hostname);
-        } else {
-            hostname = zend_string_truncate(hostname, strlen(ZSTR_VAL(hostname)), 0);
-            zval hostname_zv;
-            ZVAL_STR(&hostname_zv, hostname);
-            zend_hash_str_add_new(meta, ZEND_STRL("_dd.hostname"), &hostname_zv);
+            zend_string *hostname = zend_string_alloc(HOST_NAME_MAX, 0);
+            if (gethostname(ZSTR_VAL(hostname), HOST_NAME_MAX + 1)) {
+                zend_string_release(hostname);
+            } else {
+                hostname = zend_string_truncate(hostname, strlen(ZSTR_VAL(hostname)), 0);
+                zval hostname_zv;
+                ZVAL_STR(&hostname_zv, hostname);
+                zend_hash_str_add_new(meta, ZEND_STRL("_dd.hostname"), &hostname_zv);
+            }
         }
     }
 
diff --git a/src/DDTrace/OpenTelemetry/CompositeResolver.php b/src/DDTrace/OpenTelemetry/CompositeResolver.php
new file mode 100644
index 00000000000..58d5822b002
--- /dev/null
+++ b/src/DDTrace/OpenTelemetry/CompositeResolver.php
@@ -0,0 +1,125 @@
+<?php
+// This file does not actually replace the CompositeResolver, but it's guaranteed to be autoloaded before the actual CompositeResolver.
+// We just hook the CompositeResolver to track it.
+
+use OpenTelemetry\Contrib\Otlp\OtlpUtil;
+use OpenTelemetry\API\Signals;
+
+\DDTrace\install_hook(
+    'OpenTelemetry\SDK\Common\Configuration\Resolver\CompositeResolver::__construct',
+    null,
+    function (\DDTrace\HookData $hook) {
+
+        $this->addResolver(new class () implements \OpenTelemetry\SDK\Common\Configuration\Resolver\ResolverInterface {
+            public function retrieveValue(string $name): mixed
+            {
+                // Only configure metrics-related settings if DD_METRICS_OTEL_ENABLED is true
+                if (($name === 'OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE' ||
+                     $name === 'OTEL_EXPORTER_OTLP_METRICS_ENDPOINT') &&
+                    !\dd_trace_env_config('DD_METRICS_OTEL_ENABLED')) {
+                    return null;
+                }
+
+                if ($name === 'OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE') {
+                    return "delta";
+                }
+                if ($name === 'OTEL_EXPORTER_OTLP_ENDPOINT' || $name === 'OTEL_EXPORTER_OTLP_METRICS_ENDPOINT') {
+                    // Determine protocol
+                    $protocol = null;
+
+                    if ($name === 'OTEL_EXPORTER_OTLP_METRICS_ENDPOINT' && \OpenTelemetry\SDK\Common\Configuration\Configuration::has('OTEL_EXPORTER_OTLP_METRICS_PROTOCOL')) {
+                        // Get metrics-specific protocol
+                        $protocol = \OpenTelemetry\SDK\Common\Configuration\Configuration::getEnum('OTEL_EXPORTER_OTLP_METRICS_PROTOCOL');
+                    }
+
+                    if ($protocol === null) {
+                        // Get general OTLP protocol
+                        $protocol = \OpenTelemetry\SDK\Common\Configuration\Configuration::getEnum('OTEL_EXPORTER_OTLP_PROTOCOL');
+                    }
+
+                    if ($protocol === null) {
+                        // Use language default
+                        $protocol = 'http/protobuf';
+                    }
+
+                    // Determine endpoint
+
+                    // Check for general OTLP endpoint (only when requesting metrics endpoint)
+                    if ($name === 'OTEL_EXPORTER_OTLP_METRICS_ENDPOINT' && \OpenTelemetry\SDK\Common\Configuration\Configuration::has('OTEL_EXPORTER_OTLP_ENDPOINT')) {
+                        $generalEndpoint = rtrim(\OpenTelemetry\SDK\Common\Configuration\Configuration::getString('OTEL_EXPORTER_OTLP_ENDPOINT'), '/');
+                        // May need to add subpath for metrics endpoint with HTTP protocol
+                        if ($protocol !== 'grpc') {
+                            return "$generalEndpoint/v1/metrics";
+                        }
+                        return $generalEndpoint.OtlpUtil::method(Signals::METRICS);
+                    }
+
+                    // Get agent host from DD_AGENT_HOST or DD_TRACE_AGENT_URL
+                    $host = null;
+                    $scheme = 'http';
+                    $port = null;
+
+                    // First check DD_TRACE_AGENT_URL for unix sockets or full URLs
+                    $agentUrl = \dd_trace_env_config('DD_TRACE_AGENT_URL');
+                    if ($agentUrl !== '') {
+                        $component = \parse_url($agentUrl);
+                        if ($component !== false) {
+                            $scheme = $component['scheme'] ?? 'http';
+
+                            // Handle unix scheme - return as-is
+                            if ($scheme === 'unix') {
+                                // Unix sockets: pass through the full URL
+                                // The SDK must be configured with a URL in the format unix:///path/to/socket.sock
+                                return $agentUrl;
+                            }
+
+                            $host = $component['host'] ?? null;
+                        }
+                    }
+
+                    // Fall back to DD_AGENT_HOST if no URL was set
+                    if ($host === null) {
+                        $ddAgentHost = \dd_trace_env_config('DD_AGENT_HOST');
+                        if ($ddAgentHost !== '') {
+                            $host = $ddAgentHost;
+                        }
+                    }
+
+                    // Build endpoint: {scheme}://{host}:{port}
+                    if ($host === '') {
+                        $host = 'localhost';
+                    }
+
+                    // Determine port based on protocol if not already set
+                    $port = ($protocol === 'grpc') ? '4317' : '4318';
+                    $endpoint = $scheme . '://' . $host . ':' . $port;
+
+                    if ($name === 'OTEL_EXPORTER_OTLP_METRICS_ENDPOINT') {
+                        // Add subpath for metrics endpoint with HTTP protocol
+                        if ($protocol !== 'grpc') {
+                            return $endpoint.'/v1/metrics';
+                        }
+                        else {
+                            return $endpoint.OtlpUtil::method(Signals::METRICS);
+                        }
+                    }
+                    return $endpoint;
+                }
+
+                // Explicitly return null to match the original implicit behavior.
+                return null;
+            }
+
+            public function hasVariable(string $variableName): bool {
+                // Only provide default values if DD_METRICS_OTEL_ENABLED is true
+                // AND the variable is not already set in the environment
+                if ($variableName === 'OTEL_EXPORTER_OTLP_METRICS_ENDPOINT' || 
+                    $variableName === 'OTEL_EXPORTER_OTLP_ENDPOINT' ||
+                    $variableName === 'OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE') {
+                    return \dd_trace_env_config('DD_METRICS_OTEL_ENABLED');
+                }
+                return false;
+            }
+        });
+    }
+);
\ No newline at end of file
diff --git a/src/DDTrace/OpenTelemetry/Detectors/Environment.php b/src/DDTrace/OpenTelemetry/Detectors/Environment.php
new file mode 100644
index 00000000000..35b72b704f4
--- /dev/null
+++ b/src/DDTrace/OpenTelemetry/Detectors/Environment.php
@@ -0,0 +1,29 @@
+<?php
+
+use OpenTelemetry\SDK\Common\Attribute\AttributesFactory;
+use OpenTelemetry\SDK\Resource\ResourceInfo;
+
+\DDTrace\install_hook(
+    'OpenTelemetry\SDK\Resource\Detectors\Environment::getResource',
+    null,
+    function (\DDTrace\HookData $hook) {
+        $attributes = [];
+
+        if (\dd_trace_env_config('DD_ENV')!='') {
+            $attributes['deployment.environment.name'] = \dd_trace_env_config('DD_ENV');
+        }
+
+        if (\dd_trace_env_config('DD_VERSION') != '') {
+            $attributes['service.version'] = \dd_trace_env_config('DD_VERSION');
+        }
+
+        foreach (\dd_trace_env_config('DD_TAGS') as $key => $value) {
+            $attributes[$key] = $value;
+        }
+
+        $builder = (new AttributesFactory)->builder($attributes);
+        $newResource = ResourceInfo::create($builder->build());
+        $resource = $hook->returned;
+        $resource = $resource->merge($newResource);
+        $hook->overrideReturnValue($resource);
+    });
\ No newline at end of file
diff --git a/src/DDTrace/OpenTelemetry/Detectors/Host.php b/src/DDTrace/OpenTelemetry/Detectors/Host.php
new file mode 100644
index 00000000000..f9245444d88
--- /dev/null
+++ b/src/DDTrace/OpenTelemetry/Detectors/Host.php
@@ -0,0 +1,21 @@
+<?php
+
+use OpenTelemetry\SDK\Common\Attribute\AttributesFactory;
+use OpenTelemetry\SDK\Resource\ResourceInfo;
+
+\DDTrace\install_hook(
+    'OpenTelemetry\SDK\Resource\Detectors\Host::getResource',
+    null,
+    function (\DDTrace\HookData $hook) {
+        $attributes = [];
+
+        if (\dd_trace_env_config('DD_TRACE_REPORT_HOSTNAME')) {
+            $attributes['host.name'] = \dd_trace_env_config('DD_HOSTNAME');
+        }
+
+        $builder = (new AttributesFactory)->builder($attributes);
+        $newResource = ResourceInfo::create($builder->build());
+        $resource = $hook->returned;
+        $resource = $resource->merge($newResource);
+        $hook->overrideReturnValue($resource);
+    });
\ No newline at end of file
diff --git a/src/DDTrace/OpenTelemetry/Detectors/Service.php b/src/DDTrace/OpenTelemetry/Detectors/Service.php
new file mode 100644
index 00000000000..8c8bac91aac
--- /dev/null
+++ b/src/DDTrace/OpenTelemetry/Detectors/Service.php
@@ -0,0 +1,27 @@
+<?php
+
+use OpenTelemetry\SDK\Common\Attribute\AttributesFactory;
+use OpenTelemetry\SDK\Resource\ResourceInfo;
+
+\DDTrace\install_hook(
+    'OpenTelemetry\SDK\Resource\Detectors\Service::getResource',
+    null,
+    function (\DDTrace\HookData $hook) {
+        $attributes = [];
+
+        $rootSpan = \DDTrace\root_span();
+        if ($rootSpan) {
+            $attributes['service.name'] = $rootSpan->service;
+        } else {
+            if (ddtrace_config_app_name() === '') {
+                return;
+            }
+            $attributes['service.name'] = \ddtrace_config_app_name();
+        }
+        
+        $builder = (new AttributesFactory)->builder($attributes);
+        $newResource = ResourceInfo::create($builder->build());
+        $resource = $hook->returned;
+        $resource = $resource->merge($newResource);
+        $hook->overrideReturnValue($resource);
+    });
\ No newline at end of file
diff --git a/src/DDTrace/OpenTelemetry/Span.php b/src/DDTrace/OpenTelemetry/Span.php
index 14ef8b5684e..d298013ca49 100644
--- a/src/DDTrace/OpenTelemetry/Span.php
+++ b/src/DDTrace/OpenTelemetry/Span.php
@@ -274,7 +274,7 @@ public function getKind(): int
     /**
      * @inheritDoc
      */
-    public function getAttribute(string $key)
+    public function getAttribute(string $key): mixed
     {
         return $this->span->meta[$key] ?? ($this->span->metrics[$key] ?? null);
     }
diff --git a/src/bridge/_files_opentelemetry.php b/src/bridge/_files_opentelemetry.php
index e5e2a91d707..57efda17bf3 100644
--- a/src/bridge/_files_opentelemetry.php
+++ b/src/bridge/_files_opentelemetry.php
@@ -3,8 +3,12 @@
 return [
     __DIR__ . '/../DDTrace/OpenTelemetry/Context.php',
     __DIR__ . '/../DDTrace/OpenTelemetry/Convention.php',
+    __DIR__ . '/../DDTrace/OpenTelemetry/CompositeResolver.php',
     __DIR__ . '/../DDTrace/OpenTelemetry/SpanContext.php',
     __DIR__ . '/../DDTrace/OpenTelemetry/Span.php',
     __DIR__ . '/../DDTrace/OpenTelemetry/SpanBuilder.php',
     __DIR__ . '/../DDTrace/OpenTelemetry/CachedInstrumentation.php',
+    __DIR__ . '/../DDTrace/OpenTelemetry/Detectors/Environment.php',
+    __DIR__ . '/../DDTrace/OpenTelemetry/Detectors/Host.php',
+    __DIR__ . '/../DDTrace/OpenTelemetry/Detectors/Service.php',
 ];