From 61fbef42a6eeae7553f148f1759c5a770a2f65aa Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Sat, 18 Oct 2025 18:47:27 +0300
Subject: [PATCH 1/2] libstore: Simplify check for S3-specific URI query
 parameters

Instead of hardcoding strings we should instead use the setting
objects to determine the query names that should be preserved.
---
 .../include/nix/store/s3-binary-cache-store.hh    |  8 ++++++--
 src/libstore/s3-binary-cache-store.cc             | 15 +++++++--------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/libstore/include/nix/store/s3-binary-cache-store.hh b/src/libstore/include/nix/store/s3-binary-cache-store.hh
index c8cb967c1..e5fcbeda3 100644
--- a/src/libstore/include/nix/store/s3-binary-cache-store.hh
+++ b/src/libstore/include/nix/store/s3-binary-cache-store.hh
@@ -21,8 +21,6 @@ struct S3BinaryCacheStoreConfig : HttpBinaryCacheStoreConfig
           Nix uses the `default` profile.
         )"};
 
-public:
-
     const Setting<std::string> region{
         this,
         "us-east-1",
@@ -63,6 +61,12 @@ public:
           > addressing instead of virtual host based addressing.
         )"};
 
+    /**
+     * Set of settings that are part of the S3 URI itself.
+     * These are needed for region specification and other S3-specific settings.
+     */
+    const std::set<const AbstractSetting *> s3UriSettings = {&profile, &region, &scheme, &endpoint};
+
     static const std::string name()
     {
         return "S3 Binary Cache Store";
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index a84ea5fcb..ac08a4982 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -1,10 +1,10 @@
 #include "nix/store/s3-binary-cache-store.hh"
-
-#include <cassert>
-
 #include "nix/store/http-binary-cache-store.hh"
 #include "nix/store/store-registration.hh"
 
+#include <cassert>
+#include <ranges>
+
 namespace nix {
 
 StringSet S3BinaryCacheStoreConfig::uriSchemes()
@@ -17,14 +17,13 @@ S3BinaryCacheStoreConfig::S3BinaryCacheStoreConfig(
     : StoreConfig(params)
     , HttpBinaryCacheStoreConfig(scheme, _cacheUri, params)
 {
-    // For S3 stores, preserve S3-specific query parameters as part of the URL
-    // These are needed for region specification and other S3-specific settings
     assert(cacheUri.query.empty());
+    assert(cacheUri.scheme == "s3");
 
-    // Only copy S3-specific parameters to the URL query
-    static const std::set<std::string> s3Params = {"region", "endpoint", "profile", "scheme"};
     for (const auto & [key, value] : params) {
-        if (s3Params.contains(key)) {
+        auto s3Params =
+            std::views::transform(s3UriSettings, [](const AbstractSetting * setting) { return setting->name; });
+        if (std::ranges::contains(s3Params, key)) {
             cacheUri.query[key] = value;
         }
     }

From 3d147c04a5f9d03e1696fb25b495a077885d2cf7 Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Sat, 18 Oct 2025 19:11:39 +0300
Subject: [PATCH 2/2] libstore: Implement getHumanReadableURI for
 S3BinaryCacheStoreConfig

This slightly improves the logs situation by including the region/profile/endpoint
in the logs when S3 store references get printed. Instead of:

copying path '/nix/store/lxnp9cs4cfh2g9r2bs4z7gwwz9kdj2r9-test-package-c' to 's3://bucketname'...

This now includes:

copying path '/nix/store/lxnp9cs4cfh2g9r2bs4z7gwwz9kdj2r9-test-package-c' to 's3://bucketname?endpoint=http://server:9000&region=eu-west-1'...
---
 .../include/nix/store/s3-binary-cache-store.hh      |  2 ++
 src/libstore/s3-binary-cache-store.cc               | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/src/libstore/include/nix/store/s3-binary-cache-store.hh b/src/libstore/include/nix/store/s3-binary-cache-store.hh
index e5fcbeda3..288ca41a0 100644
--- a/src/libstore/include/nix/store/s3-binary-cache-store.hh
+++ b/src/libstore/include/nix/store/s3-binary-cache-store.hh
@@ -75,6 +75,8 @@ struct S3BinaryCacheStoreConfig : HttpBinaryCacheStoreConfig
     static StringSet uriSchemes();
 
     static std::string doc();
+
+    std::string getHumanReadableURI() const override;
 };
 
 } // namespace nix
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index ac08a4982..0b37ac5d7 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -29,6 +29,19 @@ S3BinaryCacheStoreConfig::S3BinaryCacheStoreConfig(
     }
 }
 
+std::string S3BinaryCacheStoreConfig::getHumanReadableURI() const
+{
+    auto reference = getReference();
+    reference.params = [&]() {
+        Params relevantParams;
+        for (auto & setting : s3UriSettings)
+            if (setting->overridden)
+                relevantParams.insert({setting->name, reference.params.at(setting->name)});
+        return relevantParams;
+    }();
+    return reference.render();
+}
+
 std::string S3BinaryCacheStoreConfig::doc()
 {
     return R"(