fix(executor): scrape the execution client through a short network alias

CLAUDE.md

@@ -314,7 +314,9 @@ Each scenario creates an isolated Docker bridge network:
 
 - Execution client container joins the network
 - K6 and Alloy containers join the same network
-- Enables service discovery by container name
+- Enables service discovery by container name; the execution client is also reachable as
+  `execution-client` (Alloy scrapes that alias, because container names longer than 63
+  characters do not resolve)
 - Network is removed during cleanup
 
 ### Resource Limiting

src/expb/_version.py

@@ -1,2 +1,2 @@
-__version__ = "0.1.0"
-__commit__ = "7621458"
+__version__ = "0.1.0"
+__commit__ = "9609a1b"

src/expb/payloads/executor/executor.py

@@ -681,7 +681,26 @@ def start_execution_client(
             run_kwargs["mem_swappiness"] = self.config.resources.mem_swappiness
         if self.config.execution_client_security_opt:
             run_kwargs["security_opt"] = self.config.execution_client_security_opt
-        container = self.config.docker_client.containers.run(**run_kwargs)
+        if container_network is None:
+            return self.config.docker_client.containers.run(**run_kwargs)
+        # Attach the client under its short aliases as well: the container name exceeds the
+        # 63-character DNS label limit for long scenario names, and a name that does not resolve
+        # silently leaves the client unscraped, which shows up as a spurious CPU saving.
+        name = run_kwargs["name"]
+        if len(name) > 63:
+            self.log.warning(
+                "Execution client container name exceeds the DNS label limit; use its network alias",
+                container=name,
+                aliases=self.config.get_execution_client_aliases(),
+            )
+        run_kwargs.pop("detach")
+        container = self.config.docker_client.containers.create(**run_kwargs)
+        container_network.disconnect(container)
+        container_network.connect(
+            container, aliases=self.config.get_execution_client_aliases()
+        )
+        container.start()
+        container.reload()
         return container
 
     def _client_host_pid(self, container: Container, timeout: int = 60) -> int | None:

src/expb/payloads/executor/executor_config.py

@@ -32,6 +32,9 @@
 from expb.payloads.executor.services.snapshots import SnapshotService
 
 
+EXECUTION_CLIENT_ALIAS = "execution-client"
+
+
 # ExecutorConfig class is a collection of helper functions and configuration options for the Executor class
 class ExecutorConfig:
     def __init__(
@@ -232,9 +235,15 @@ def get_execution_client_ports(self) -> dict[str, tuple[str, str]]:
             # f"{CLIENT_P2P_PORT}/udp": ("127.0.0.1", f"{CLIENT_P2P_PORT}"),
         }
 
+    def get_execution_client_aliases(self) -> list[str]:
+        # Docker's embedded DNS resolves a name only if it fits a 63-character DNS label. Scenario
+        # names push the client's container name past that, so the client also gets a short alias
+        # on the scenario network and everything that addresses it by name uses the alias.
+        return [EXECUTION_CLIENT_ALIAS]
+
     def get_execution_metrics_address(self) -> str:
-        # Metrics endpoint is required before the actual execution container is started
-        return f"{self.get_execution_client_container_name()}:{CLIENT_METRICS_PORT}"
+        # Rendered into the Alloy config before the execution container exists, so it cannot be an IP.
+        return f"{EXECUTION_CLIENT_ALIAS}:{CLIENT_METRICS_PORT}"
 
     def get_execution_client_engine_url(
         self,