Fix install using explicit url (#3710)

libmamba/include/mamba/core/package_fetcher.hpp

@@ -101,6 +101,8 @@ namespace mamba
 
         struct CheckSumParams;
 
+        bool is_local_package() const;
+        bool use_explicit_https_url() const;
         const std::string& filename() const;
         std::string channel() const;
         std::string url_path() const;

libmamba/src/core/package_fetcher.cpp

@@ -317,6 +317,19 @@ namespace mamba
     /*******************
      * Private methods *
      *******************/
+    bool PackageFetcher::is_local_package() const
+    {
+        return util::starts_with(m_package_info.package_url, "file://");
+    }
+
+    bool PackageFetcher::use_explicit_https_url() const
+    {
+        // This excludes OCI case, which uses explicitly a "oci://" scheme,
+        // but is resolved later to something starting with `oci_base_url`
+        constexpr std::string_view oci_base_url = "https://pkg-containers.githubusercontent.com/";
+        return util::starts_with(m_package_info.package_url, "https://")
+               && !util::starts_with(m_package_info.package_url, oci_base_url);
+    }
 
     const std::string& PackageFetcher::filename() const
     {
@@ -325,26 +338,24 @@ namespace mamba
 
     std::string PackageFetcher::channel() const
     {
-        if (!util::starts_with(m_package_info.package_url, "file://"))
-        {
-            return m_package_info.channel;
-        }
-        else  // local package case
+        if (is_local_package() || use_explicit_https_url())
         {
+            // Use explicit url or local package path
+            // to fetch package, leaving the channel empty.
             return "";
         }
+        return m_package_info.channel;
     }
 
     std::string PackageFetcher::url_path() const
     {
-        if (!util::starts_with(m_package_info.package_url, "file://"))
-        {
-            return util::concat(m_package_info.platform, '/', m_package_info.filename);
-        }
-        else  // local package case
+        if (is_local_package() || use_explicit_https_url())
         {
+            // Use explicit url or local package path
+            // to fetch package.
             return m_package_info.package_url;
         }
+        return util::concat(m_package_info.platform, '/', m_package_info.filename);
     }
 
     const std::string& PackageFetcher::url() const

micromamba/tests/test_create.py

@@ -1169,6 +1169,46 @@ def test_create_with_non_existing_subdir(tmp_home, tmp_root_prefix, tmp_path):
         helpers.create("-p", env_prefix, "--dry-run", "--json", "conda-forge/noarch::xtensor")
 
 
+@pytest.mark.parametrize(
+    "spec",
+    [
+        "https://conda.anaconda.org/conda-forge/linux-64/_libgcc_mutex-0.1-main.tar.bz2",
+        "https://conda.anaconda.org/conda-forge/linux-64/abacus-3.2.4-hb6c440e_0.conda",
+    ],
+)
+def test_create_with_explicit_url(tmp_home, tmp_root_prefix, tmp_path, spec):
+    """Attempts to install a package using an explicit url."""
+    empty_root_prefix = tmp_path / "empty-root-create-from-explicit-url"
+    env_name = "env-create-from-explicit-url"
+
+    os.environ["MAMBA_ROOT_PREFIX"] = str(empty_root_prefix)
+
+    res = helpers.create(
+        spec, "--no-env", "-n", env_name, "--override-channels", "--json", default_channel=False
+    )
+    assert res["success"]
+
+    pkgs = res["actions"]["LINK"]
+    if spec.endswith(".tar.bz2"):
+        assert len(pkgs) == 1
+        assert pkgs[0]["name"] == "_libgcc_mutex"
+        assert pkgs[0]["version"] == "0.1"
+        assert (
+            pkgs[0]["url"]
+            == "https://conda.anaconda.org/conda-forge/linux-64/_libgcc_mutex-0.1-main.tar.bz2"
+        )
+        assert pkgs[0]["channel"] == "https://conda.anaconda.org/conda-forge"
+    else:
+        assert len(pkgs) == 1
+        assert pkgs[0]["name"] == "abacus"
+        assert pkgs[0]["version"] == "3.2.4"
+        assert (
+            pkgs[0]["url"]
+            == "https://conda.anaconda.org/conda-forge/linux-64/abacus-3.2.4-hb6c440e_0.conda"
+        )
+        assert pkgs[0]["channel"] == "https://conda.anaconda.org/conda-forge"
+
+
 @pytest.mark.parametrize("shared_pkgs_dirs", [True], indirect=True)
 def test_create_with_multiple_files(tmp_home, tmp_root_prefix, tmpdir):
     env_name = "myenv"