feat(libstore/s3): add toHttpsUrl

This is extracted from the work in #13752

src/libstore-tests/s3.cc

@@ -35,7 +35,8 @@ INSTANTIATE_TEST_SUITE_P(
                 .bucket = "my-bucket",
                 .key = "my-key.txt",
             },
-            "basic_s3_bucket"},
+            "basic_s3_bucket",
+        },
         ParsedS3URLTestCase{
             "s3://prod-cache/nix/store/abc123.nar.xz?region=eu-west-1",
             {
@@ -43,7 +44,8 @@ INSTANTIATE_TEST_SUITE_P(
                 .key = "nix/store/abc123.nar.xz",
                 .region = "eu-west-1",
             },
-            "with_region"},
+            "with_region",
+        },
         ParsedS3URLTestCase{
             "s3://bucket/key?region=us-west-2&profile=prod&endpoint=custom.s3.com&scheme=https&region=us-east-1",
             {
@@ -54,7 +56,8 @@ INSTANTIATE_TEST_SUITE_P(
                 .scheme = "https",
                 .endpoint = ParsedURL::Authority{.host = "custom.s3.com"},
             },
-            "complex"},
+            "complex",
+        },
         ParsedS3URLTestCase{
             "s3://cache/file.txt?profile=production&region=ap-southeast-2",
             {
@@ -63,7 +66,8 @@ INSTANTIATE_TEST_SUITE_P(
                 .profile = "production",
                 .region = "ap-southeast-2",
             },
-            "with_profile_and_region"},
+            "with_profile_and_region",
+        },
         ParsedS3URLTestCase{
             "s3://bucket/key?endpoint=https://minio.local&scheme=http",
             {
@@ -77,7 +81,8 @@ INSTANTIATE_TEST_SUITE_P(
                         .authority = ParsedURL::Authority{.host = "minio.local"},
                     },
             },
-            "with_absolute_endpoint_uri"}),
+            "with_absolute_endpoint_uri",
+        }),
     [](const ::testing::TestParamInfo<ParsedS3URLTestCase> & info) { return info.param.description; });
 
 TEST(InvalidParsedS3URLTest, parseS3URLErrors)
@@ -91,6 +96,101 @@ TEST(InvalidParsedS3URLTest, parseS3URLErrors)
     ASSERT_THAT([]() { ParsedS3URL::parse(parseURL("s3://127.0.0.1")); }, invalidBucketMatcher);
 }
 
+// Parameterized test for s3ToHttpsUrl conversion
+struct S3ToHttpsConversionTestCase
+{
+    ParsedS3URL input;
+    ParsedURL expected;
+    std::string description;
+};
+
+class S3ToHttpsConversionTest : public ::testing::WithParamInterface<S3ToHttpsConversionTestCase>,
+                                public ::testing::Test
+{};
+
+TEST_P(S3ToHttpsConversionTest, ConvertsCorrectly)
+{
+    const auto & testCase = GetParam();
+    auto result = testCase.input.toHttpsUrl();
+    EXPECT_EQ(result, testCase.expected) << "Failed for: " << testCase.description;
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    S3ToHttpsConversion,
+    S3ToHttpsConversionTest,
+    ::testing::Values(
+        S3ToHttpsConversionTestCase{
+            ParsedS3URL{
+                .bucket = "my-bucket",
+                .key = "my-key.txt",
+            },
+            ParsedURL{
+                .scheme = "https",
+                .authority = ParsedURL::Authority{.host = "s3.us-east-1.amazonaws.com"},
+                .path = "/my-bucket/my-key.txt",
+            },
+            "basic_s3_default_region",
+        },
+        S3ToHttpsConversionTestCase{
+            ParsedS3URL{
+                .bucket = "prod-cache",
+                .key = "nix/store/abc123.nar.xz",
+                .region = "eu-west-1",
+            },
+            ParsedURL{
+                .scheme = "https",
+                .authority = ParsedURL::Authority{.host = "s3.eu-west-1.amazonaws.com"},
+                .path = "/prod-cache/nix/store/abc123.nar.xz",
+            },
+            "with_eu_west_1_region",
+        },
+        S3ToHttpsConversionTestCase{
+            ParsedS3URL{
+                .bucket = "bucket",
+                .key = "key",
+                .scheme = "http",
+                .endpoint = ParsedURL::Authority{.host = "custom.s3.com"},
+            },
+            ParsedURL{
+                .scheme = "http",
+                .authority = ParsedURL::Authority{.host = "custom.s3.com"},
+                .path = "/bucket/key",
+            },
+            "custom_endpoint_authority",
+        },
+        S3ToHttpsConversionTestCase{
+            ParsedS3URL{
+                .bucket = "bucket",
+                .key = "key",
+                .endpoint =
+                    ParsedURL{
+                        .scheme = "http",
+                        .authority = ParsedURL::Authority{.host = "server", .port = 9000},
+                    },
+            },
+            ParsedURL{
+                .scheme = "http",
+                .authority = ParsedURL::Authority{.host = "server", .port = 9000},
+                .path = "/bucket/key",
+            },
+            "custom_endpoint_with_port",
+        },
+        S3ToHttpsConversionTestCase{
+            ParsedS3URL{
+                .bucket = "bucket",
+                .key = "path/to/file.txt",
+                .region = "ap-southeast-2",
+                .scheme = "https",
+            },
+            ParsedURL{
+                .scheme = "https",
+                .authority = ParsedURL::Authority{.host = "s3.ap-southeast-2.amazonaws.com"},
+                .path = "/bucket/path/to/file.txt",
+            },
+            "complex_path_and_region",
+        }),
+    [](const ::testing::TestParamInfo<S3ToHttpsConversionTestCase> & info) { return info.param.description; });
+
 } // namespace nix
 
 #endif

src/libstore/include/nix/store/s3.hh

@@ -75,6 +75,12 @@ struct ParsedS3URL
     }
 
     static ParsedS3URL parse(const ParsedURL & uri);
+
+    /**
+     * Convert this ParsedS3URL to HTTPS ParsedURL for use with curl's AWS SigV4 authentication
+     */
+    ParsedURL toHttpsUrl() const;
+
     auto operator<=>(const ParsedS3URL & other) const = default;
 };
 

src/libstore/s3.cc

@@ -1,6 +1,8 @@
 #include "nix/store/s3.hh"
 #include "nix/util/split.hh"
 #include "nix/util/url.hh"
+#include "nix/util/util.hh"
+#include "nix/util/canon-path.hh"
 
 namespace nix {
 
@@ -64,6 +66,42 @@ try {
     throw;
 }
 
+ParsedURL ParsedS3URL::toHttpsUrl() const
+{
+    std::string regionStr = region.value_or("us-east-1");
+    std::string schemeStr = scheme.value_or("https");
+
+    // Handle endpoint configuration using std::visit
+    return std::visit(
+        overloaded{
+            [&](const std::monostate &) {
+                // No custom endpoint, use standard AWS S3 endpoint
+                return ParsedURL{
+                    .scheme = schemeStr,
+                    .authority = ParsedURL::Authority{.host = "s3." + regionStr + ".amazonaws.com"},
+                    .path = (CanonPath::root / bucket / CanonPath(key)).abs(),
+                };
+            },
+            [&](const ParsedURL::Authority & auth) {
+                // Endpoint is just an authority (hostname/port)
+                return ParsedURL{
+                    .scheme = schemeStr,
+                    .authority = auth,
+                    .path = (CanonPath::root / bucket / CanonPath(key)).abs(),
+                };
+            },
+            [&](const ParsedURL & endpointUrl) {
+                // Endpoint is already a ParsedURL (e.g., http://server:9000)
+                return ParsedURL{
+                    .scheme = endpointUrl.scheme,
+                    .authority = endpointUrl.authority,
+                    .path = (CanonPath(endpointUrl.path) / bucket / CanonPath(key)).abs(),
+                };
+            },
+        },
+        endpoint);
+}
+
 #endif
 
 } // namespace nix