fix: Resolve ca-certificates installed in the local environment

libmamba/src/download/downloader.cpp

@@ -8,6 +8,7 @@
 #include "mamba/core/invoke.hpp"
 #include "mamba/core/thread_utils.hpp"
 #include "mamba/core/util.hpp"
+#include "mamba/core/util_os.hpp"
 #include "mamba/core/util_scope.hpp"
 #include "mamba/download/downloader.hpp"
 #include "mamba/util/build.hpp"
@@ -84,19 +85,41 @@ namespace mamba::download
                 // from `conda-forge::ca-certificates` and the system CA certificates.
                 else if (remote_fetch_params.ssl_verify == "<system>")
                 {
-                    // Use the CA certificates from `conda-forge::ca-certificates` installed in the
-                    // root prefix or the system CA certificates if the certificate is not present.
-                    fs::u8path root_prefix = detail::get_root_prefix();
-                    fs::u8path env_prefix_conda_cert = root_prefix / "ssl" / "cacert.pem";
-
-                    LOG_INFO << "Checking for CA certificates at the root prefix: "
+                    const fs::u8path executable_path = get_self_exe_path();
+                    // Find the supposed environment prefix.
+                    // `mamba` or `micromamba` is installed at:
+                    //    - `${PREFIX}/bin/{mamba,micromamba}` on Unix
+                    //    - `${PREFIX}/Library/bin/{mamba,micromamba}.exe` on Windows
+                    const fs::u8path env_prefix
+                        = (util::on_win ? executable_path.parent_path().parent_path().parent_path()
+                                        : executable_path.parent_path().parent_path());
+
+                    const fs::u8path env_prefix_conda_cert = env_prefix / "ssl" / "cacert.pem";
+
+                    LOG_INFO << "Checking for CA certificates in the same environment as the executable installation: "
                              << env_prefix_conda_cert;
 
                     if (fs::exists(env_prefix_conda_cert))
                     {
-                        LOG_INFO << "Using CA certificates from `conda-forge::ca-certificates` installed in the root prefix "
+                        LOG_INFO << "Using CA certificates from the same prefix as the executable installation "
                                  << "(i.e " << env_prefix_conda_cert << ")";
                         remote_fetch_params.ssl_verify = env_prefix_conda_cert;
+                        return;
+                    }
+
+                    // Try to use the CA certificates from `conda-forge::ca-certificates` installed
+                    // in the root prefix.
+                    const fs::u8path root_prefix = detail::get_root_prefix();
+                    const fs::u8path root_prefix_conda_cert = root_prefix / "ssl" / "cacert.pem";
+
+                    LOG_INFO << "Checking for CA certificates at the root prefix: "
+                             << root_prefix_conda_cert;
+
+                    if (fs::exists(root_prefix_conda_cert))
+                    {
+                        LOG_INFO << "Using CA certificates from `conda-forge::ca-certificates` installed in the root prefix "
+                                 << "(i.e " << root_prefix_conda_cert << ")";
+                        remote_fetch_params.ssl_verify = root_prefix_conda_cert;
                         remote_fetch_params.curl_initialized = true;
                         return;
                     }

micromamba/tests/test_env.py

@@ -1,6 +1,7 @@
 import os
 import re
 import shutil
+import subprocess
 
 from packaging.version import Version
 from pathlib import Path
@@ -525,3 +526,30 @@ def test_env_export_with_pip(tmp_path, json_flag):
     # Check that `requests` and `urllib3` (pulled dependency) are exported
     assert "requests==2.32.3" in pip_section_vals
     assert any(pkg.startswith("urllib3==") for pkg in pip_section_vals)
+
+
+def test_env_export_with_ca_certificates(tmp_path):
+    # CA certificates in the same environment as `mamba` or `micromamba`
+    # executable installation are used by default.
+    tmp_env_prefix = tmp_path / "env-export-with-ca-certificates"
+
+    helpers.create("-p", tmp_env_prefix, "ca-certificates", no_dry_run=True)
+
+    # Copy the `micromamba` executable in this prefix `bin` subdirectory
+    (tmp_env_prefix / "bin").mkdir(parents=True, exist_ok=True)
+    tmp_env_micromamba = tmp_env_prefix / "bin" / "micromamba"
+    shutil.copy(helpers.get_umamba(), tmp_env_micromamba)
+
+    # Run a command using mamba in verbose mode and check that the ca-certificates file
+    # from the same environment as the executable is used by default.
+    p = subprocess.run(
+        [tmp_env_micromamba, "search", "xtensor", "-v"],
+        capture_output=True,
+        check=False,
+    )
+    stderr = p.stderr.decode()
+    assert (
+        "Checking for CA certificates in the same environment as the executable installation"
+        in stderr
+    )
+    assert "Using CA certificates from the same prefix as the executable installation" in stderr