add default envs to container-client (#4439)

Author: anonrig

src/workerd/server/container-client.c++

@@ -271,14 +271,19 @@ kj::Promise<void> ContainerClient::createContainer(
     }
   }
 
-  // Add environment variables if provided
+  auto envSize = environment.map([](auto& env) { return env.size(); }).orDefault(0);
+  auto jsonEnv = jsonRoot.initEnv(envSize + kj::size(defaultEnv));
+
   KJ_IF_SOME(env, environment) {
-    auto jsonEnv = jsonRoot.initEnv(env.size());
     for (uint32_t i: kj::zeroTo(env.size())) {
       jsonEnv.set(i, env[i]);
     }
   }
 
+  for (uint32_t i: kj::zeroTo(kj::size(defaultEnv))) {
+    jsonEnv.set(envSize + i, defaultEnv[i]);
+  }
+
   auto hostConfig = jsonRoot.initHostConfig();
   // We need to publish all ports to properly get the mapped port number locally
   hostConfig.setPublishAllPorts(true);

src/workerd/server/container-client.h

@@ -49,6 +49,12 @@ class ContainerClient final: public rpc::Container::Server {
   kj::String imageName;
   kj::TaskSet& waitUntilTasks;
 
+  static constexpr kj::StringPtr defaultEnv[] = {"CLOUDFLARE_COUNTRY_A2=XX"_kj,
+    "CLOUDFLARE_DEPLOYMENT_ID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"_kj,
+    "CLOUDFLARE_LOCATION=loc01"_kj, "CLOUDFLARE_REGION=REGN"_kj,
+    "CLOUDFLARE_APPLICATION_ID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"_kj,
+    "CLOUDFLARE_DURABLE_OBJECT_ID=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"_kj};
+
   // Docker-specific Port implementation
   class DockerPort;