TargetCache: Use StorageConfig instance for sharding

Instead of computing the shard based on the RemoteExecutionConfig
singleton, use the already computed hash stored in the passed
StorageConfig instance, which now needs to be set up separately
if bootstrapping in order to avoid unwanted includes.

Storing the backend description to CAS and corresponding audit
checks now take place in main.

1 files changed, 25 insertions, 0 deletions

diff --git a/src/buildtool/main/main.cpp b/src/buildtool/main/main.cpp
index 716545a5..a82a6db8 100644
--- a/src/buildtool/main/main.cpp
+++ b/src/buildtool/main/main.cpp
@@ -80,7 +80,9 @@
 #include "src/buildtool/progress_reporting/progress_reporter.hpp"
 #include "src/buildtool/serve_api/remote/config.hpp"
 #include "src/buildtool/serve_api/serve_service/serve_server_implementation.hpp"
+#include "src/buildtool/storage/backend_description.hpp"
 #include "src/buildtool/storage/garbage_collector.hpp"
+#include "src/utils/cpp/gsl.hpp"
 #endif  // BOOTSTRAP_BUILD_TOOL
 
 namespace {
@@ -291,6 +293,23 @@ void SetupFileChunker() {
     FileChunker::Initialize();
 }
 
+/// \brief Write backend description (which determines the target cache shard)
+/// to CAS.
+void StoreTargetCacheShard(StorageConfig const& storage_config,
+                           Storage const& storage) noexcept {
+    auto backend_description =
+        DescribeBackend(RemoteExecutionConfig::RemoteAddress(),
+                        RemoteExecutionConfig::PlatformProperties(),
+                        RemoteExecutionConfig::DispatchList());
+    if (not backend_description) {
+        Logger::Log(LogLevel::Error, backend_description.error());
+        std::exit(kExitFailure);
+    }
+    [[maybe_unused]] auto id = storage.CAS().StoreBlob(*backend_description);
+    EnsuresAudit(id and ArtifactDigest{*id}.hash() ==
+                            storage_config.backend_description_id);
+}
+
 #endif  // BOOTSTRAP_BUILD_TOOL
 
 // returns path relative to `root`.
@@ -847,6 +866,7 @@ auto main(int argc, char* argv[]) -> int {
                 return kExitFailure;
             }
             auto const storage = Storage::Create(&*storage_config);
+            StoreTargetCacheShard(*storage_config, storage);
 
             SetupExecutionServiceConfig(arguments.service);
             ApiBundle const exec_apis{&*storage_config,
@@ -879,6 +899,7 @@ auto main(int argc, char* argv[]) -> int {
                     return kExitFailure;
                 }
                 auto const storage = Storage::Create(&*storage_config);
+                StoreTargetCacheShard(*storage_config, storage);
 
                 ApiBundle const serve_apis{
                     &*storage_config,
@@ -937,6 +958,10 @@ auto main(int argc, char* argv[]) -> int {
         }
         auto const storage = Storage::Create(&*storage_config);
 
+#ifndef BOOTSTRAP_BUILD_TOOL
+        StoreTargetCacheShard(*storage_config, storage);
+#endif  // BOOTSTRAP_BUILD_TOOL
+
         auto jobs = arguments.build.build_jobs > 0 ? arguments.build.build_jobs
                                                    : arguments.common.jobs;