Support dynamic cdt_name that should help fix CI issues. (#5837)

* Adding in code to check for cdt_name. Also adding tests.

* Adding documentation.

* Update conda_build/environ.py

Co-authored-by: jaimergp <jaimergp@users.noreply.github.com>

* Update docs/source/user-guide/environment-variables.rst

Co-authored-by: jaimergp <jaimergp@users.noreply.github.com>

* Updating test to use 'el' instead of 'cos6' in linux.

* Mistype! el8.  The 8 in important.

* Adding in cdt_linking specific change.

* Trying a workaround to fix the CI.

* It may be using conda-forge so let's try conda-forge cdt.

* So I guess we were not using cf actually. Out of curosity, let's try.

* Trying to simplify cdt test to be more universal.

* simplifying even more.

* Simplifying test again and adding cdt_name.

* This might just work.

* Trying to go use conda-forge

* Using conda per review suggestion.

* Simplifying the cdt recipe.

* Adding docs.

* Updating docs.

* Adding news.

* Reverting change from another PR.

* Fixing git branching mistake so we don't override other work.

---------

Co-authored-by: jaimergp <jaimergp@users.noreply.github.com>

Author: ryanskeith

conda_build/environ.py

@@ -744,14 +744,18 @@ def linux_vars(m, get_default, prefix):
     # the GNU triplet is powerpc, not ppc. This matters.
     if build_arch.startswith("ppc"):
         build_arch = build_arch.replace("ppc", "powerpc")
-    if (
-        build_arch.startswith("powerpc")
-        or build_arch.startswith("aarch64")
-        or build_arch.startswith("s390x")
-    ):
-        build_distro = "cos7"
+    # Check if cdt_name is specified in the variant first
+    # Default based on architecture if not specified
+    if build_arch.startswith(("powerpc", "aarch64", "s390x")):
+        default_build_distro = "cos7"
+    else:
+        default_build_distro = "cos6"
+
+    # Override with variant value if provided
+    if m.config.variant:
+        build_distro = m.config.variant.get("cdt_name", default_build_distro)
     else:
-        build_distro = "cos6"
+        build_distro = default_build_distro
     # There is also QEMU_SET_ENV, but that needs to be
     # filtered so it only contains the result of `linux_vars`
     # which, before this change was empty, and after it only

docs/source/user-guide/environment-variables.rst

@@ -191,14 +191,45 @@ defined only on macOS.
    * - OSX_ARCH
      - ``i386`` or ``x86_64``, depending on Python build.
 
-The environment variable listed in the following table is
-defined only on Linux.
+The environment variables listed in the following table are
+defined only on Linux. These variables can be set from the
+shell environment, variant configuration (e.g., in
+``conda_build_config.yaml``), or use default values.
 
 .. list-table::
    :widths: 20 80
 
+   * - BUILD
+     - GNU triplet specifying the build target, for example
+       ``x86_64-conda_cos6-linux-gnu`` or ``aarch64-conda_cos7-linux-gnu``.
+       The distribution component (e.g., ``cos6``, ``cos7``, ``el8``) can be
+       customized by setting the ``cdt_name`` variable in variant
+       configuration. Defaults to ``cos6`` for most architectures, ``cos7``
+       for ``powerpc``, ``aarch64``, and ``s390x``.  If ``BUILD`` and ``cdt_name`` are both set,
+       BUILD takes precedence.
+   * - CFLAGS
+     - C compiler flags. Inherited from environment or variant
+       configuration if set, otherwise empty.
+   * - CXXFLAGS
+     - C++ compiler flags. Inherited from environment or variant
+       configuration if set, otherwise empty.
+   * - DEJAGNU
+     - DejaGnu test framework configuration. Inherited from
+       environment or variant configuration if set, otherwise empty.
+   * - DISPLAY
+     - X11 display variable. Inherited from environment or variant
+       configuration if set, otherwise empty.
    * - LD_RUN_PATH
-     - ``$PREFIX/lib``.
+     - Runtime library search path. Defaults to ``$PREFIX/lib``.
+   * - LDFLAGS
+     - Linker flags. Inherited from environment or variant
+       configuration if set, otherwise empty.
+   * - QEMU_LD_PREFIX
+     - QEMU library prefix for cross-compilation. Inherited from
+       environment or variant configuration if set, otherwise empty.
+   * - QEMU_UNAME
+     - QEMU uname information for cross-compilation. Inherited from
+       environment or variant configuration if set, otherwise empty.
 
 
 .. _git-env:

news/5733-support-cdt-dynamic-naming.md

@@ -0,0 +1,19 @@
+### Enhancements
+
+* <news item>
+
+### Bug fixes
+
+* Fixed BUILD environment variable to respect `cdt_name` variant configuration. Previously, BUILD was hardcoded to use `cos6` or `cos7` based on architecture, ignoring the `cdt_name` variant when specified. Now, if `cdt_name` is provided in the variant configuration, it will be used in the BUILD variable; otherwise, it falls back to the architecture-based default. (#5733)
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>

tests/test-recipes/metadata/_render_recipe/conda_build_config.yaml

@@ -140,11 +140,11 @@ channel_sources:
 channel_targets:
   - conda-forge main
 
+# This is synced with AnacondaRecipes/aggregate repository in the conda_build_config.yaml file.
 cdt_name:  # [linux]
-  - cos7   # [linux]
-
-  - cos7   # [linux and os.environ.get("CF_CUDA_ENABLED", "False") == "True"]
-  - cos7   # [linux and os.environ.get("CF_CUDA_ENABLED", "False") == "True"]
+  - el8   # [linux]
+  - el8   # [linux and os.environ.get("CF_CUDA_ENABLED", "False") == "True"]
+  - el8   # [linux and os.environ.get("CF_CUDA_ENABLED", "False") == "True"]
 
 docker_image:                                   # [os.environ.get("BUILD_PLATFORM", "").startswith("linux-")]
   # Native builds

tests/test-recipes/metadata/cdt_linking/build.sh

@@ -2,7 +2,32 @@
 
 set -x
 
-echo -e "#include <GL/gl.h>\nint main() { glBegin(GL_TRIANGLES); glEnd(); return 0; }">gl.c
-${CC} -o ${PREFIX}/bin/links-to-opengl-cdt -x c $(pkg-config --libs gl) -Wl,-rpath-link,${PREFIX}/lib gl.c
-find ${PREFIX} -name "libGL*"
+# Simple test that CDT packages can be linked
+# Compile a minimal program that links against PAM and libselinux from CDT packages.
+# This works on main channel currently, 2025-11-11. It may be worth creating another
+# test that uses conda-forge.
+cat > cdt_test.c << 'EOF'
+#include <stddef.h>
+#include <security/pam_appl.h>
+#include <selinux/selinux.h>
+
+int main() {
+    // Test PAM - just check that the header is available
+    const char *pam_strerror_result = pam_strerror(NULL, 0);
+    (void)pam_strerror_result;  // Suppress unused variable warning
+
+    // Test libselinux - check if SELinux is enabled
+    int selinux_enabled = is_selinux_enabled();
+    (void)selinux_enabled;  // Suppress unused variable warning
+
+    return 0;
+}
+EOF
+
+${CC} -o ${PREFIX}/bin/links-to-cdt -I${PREFIX}/include -L${PREFIX}/lib \
+    -lpam -lselinux -Wl,-rpath-link,${PREFIX}/lib cdt_test.c
+
+# Verify the libraries are present
+find ${PREFIX} -name "libpam*"
+find ${PREFIX} -name "libselinux*"
 find ${PREFIX} -name "libc.so*"

tests/test-recipes/metadata/cdt_linking/conda_build_config.yaml

@@ -0,0 +1,2 @@
+cdt_name:          # [linux]
+  - el8           # [linux]

tests/test-recipes/metadata/cdt_linking/meta.yaml

@@ -10,17 +10,5 @@ build:
 requirements:
   build:
     - {{ compiler('c') }}
-    - pkg-config
-    - {{ cdt('libxcb') }}
+    - {{ cdt('pam-devel') }}
     - {{ cdt('libselinux-devel') }}
-    - {{ cdt('libxi-devel') }}
-    - {{ cdt('libx11-devel') }}
-    - {{ cdt('libxau-devel') }}
-    - {{ cdt('libxext-devel') }}
-    - {{ cdt('libxfixes-devel') }}
-    - {{ cdt('mesa-libgl-devel') }}
-    - {{ cdt('xorg-x11-proto-devel') }}
-    - {{ cdt('mesa-dri-drivers') }}
-    - {{ cdt('libxdamage-devel') }}
-    - {{ cdt('libxxf86vm') }}
-    - expat

tests/test_environ.py

@@ -1,8 +1,13 @@
 # Copyright (C) 2014 Anaconda, Inc
 # SPDX-License-Identifier: BSD-3-Clause
 import os
+import platform
 
-from conda_build.environ import create_env
+import pytest
+
+from conda_build.environ import create_env, os_vars
+
+on_linux = platform.system() == "Linux"
 
 
 def test_environment_creation_preserves_PATH(testing_workdir, testing_config):
@@ -15,3 +20,33 @@ def test_environment_creation_preserves_PATH(testing_workdir, testing_config):
         subdir=testing_config.build_subdir,
     )
     assert os.environ["PATH"] == ref_path
+
+
+@pytest.mark.skipif(
+    not on_linux, reason="BUILD variable with cdt_name is Linux-specific"
+)
+def test_build_variable_respects_cdt_name_variant(testing_metadata):
+    """Test that BUILD environment variable uses cdt_name from variant when specified.
+
+    This addresses issue #5733 where BUILD was hardcoded to cos6/cos7 based on
+    architecture instead of respecting the cdt_name variant.
+    """
+    testing_metadata.config.variant["cdt_name"] = "el8"
+    env_vars = os_vars(testing_metadata, testing_metadata.config.host_prefix)
+
+    # Verify BUILD contains the cdt_name from variant
+    assert "conda_el8" in env_vars["BUILD"]
+
+
+@pytest.mark.skipif(
+    not on_linux, reason="BUILD variable with cdt_name is Linux-specific"
+)
+def test_build_variable_defaults_to_architecture_based_distro(testing_metadata):
+    """Test that BUILD variable defaults to cos6/cos7 when cdt_name is not specified."""
+    if "cdt_name" in testing_metadata.config.variant:
+        del testing_metadata.config.variant["cdt_name"]
+
+    env_vars = os_vars(testing_metadata, testing_metadata.config.host_prefix)
+
+    # Verify BUILD uses default cos6 or cos7 (not a custom cdt_name)
+    assert "conda_cos6" in env_vars["BUILD"] or "conda_cos7" in env_vars["BUILD"]