support dynamic saithrift URL generation (sonic-net#19528)

What is the motivation for this PR?
When the Debian codename changes, the saithrift package URL must be updated accordingly outside the test code. Otherwise, the package download may silently fail, leading to QoS SAI test failures.

This change dynamically generates the correct saithrift package URL based on the current Debian codename and explicitly reports test failure if the download fails.

How did you do it?
This change dynamically generates the correct saithrift package URL based on the current Debian codename and explicitly reports test failure if the download fails.

How did you verify/test it?
passed local tests

Author: XuChen-MSFT

tests/test_pretest.py

@@ -3,6 +3,7 @@
 import os
 import pytest
 import random
+import re
 import time
 from tests.common.helpers.port_utils import get_common_supported_speeds
 
@@ -316,15 +317,77 @@ def test_collect_pfc_pause_delay_params(duthosts, tbinfo):
         logger.warning('Unable to create file {}: {}'.format(filepath, e))
 
 
-def test_update_saithrift_ptf(request, ptfhost):
+def test_update_saithrift_ptf(request, ptfhost, duthosts, enum_dut_hostname):
     '''
     Install the correct python saithrift package on the ptf
     '''
     py_saithrift_url = request.config.getoption("--py_saithrift_url")
     if not py_saithrift_url:
         pytest.skip("No URL specified for python saithrift package")
+
+    duthost = duthosts[enum_dut_hostname]
+    output = duthost.shell("show version", module_ignore_errors=True)['stdout']
+    version_reg = re.compile(r"sonic software version: +([^\s]+)\s", re.IGNORECASE)
+    asic_reg = re.compile(r"asic: +([^\s]+)\s", re.IGNORECASE)
+    # sample value: SONiC.20240510.33, SONiC.20250505.07, SONiC.internal.129741107-8524154c2d,
+    # SONiC.master.882522-695c23859
+    version = version_reg.findall(output)[0] if version_reg.search(output) else ""
+    # only broadcom, cisco-8000, mellanox support qos sai tests
+    asic = asic_reg.findall(output)[0] if asic_reg.search(output) else ""
+
+    if "master" in version:
+        branch_name = "master"
+    elif "internal" in version:
+        branch_name = "internal"
+    else:
+        # Extract year/month from version string to determine branch
+        date_match = re.search(r'(\d{4})(\d{2})', version)
+        if date_match:
+            year, month = date_match.groups()
+            branch_name = f"internal-{year}{month}"
+        else:
+            pytest.fail("Unable to parse or recognize version format: {}".format(version))
+
+    # Apply special codename overrides for specific internal branches
+    if branch_name == "internal-202411":
+        # internal-202411 has saithrift URL hardcoded to bullseye
+        debian_codename = "bullseye"
+    elif (branch_name.startswith("internal-") and branch_name < "internal-202405"):
+        # For internal branches older than 202405, use the original URL without modification
+        # No need to get debian_codename as URL won't be modified
+        debian_codename = None
+    else:
+        # Get debian codename from syncd container (not host OS)
+        # This applies to: master branch and internal branches >= 202405 (except 202411)
+        try:
+            # Try to get codename from syncd container
+            syncd_codename_cmd = ("docker exec syncd grep VERSION_CODENAME /etc/os-release | "
+                                  "cut -d= -f2 | tr -d '\"'")
+            syncd_codename_result = duthost.shell(syncd_codename_cmd, module_ignore_errors=True)
+            if syncd_codename_result['rc'] == 0 and syncd_codename_result['stdout'].strip():
+                debian_codename = syncd_codename_result['stdout'].strip()
+            else:
+                pytest.fail("Failed to get debian codename from syncd container. RC: {}, Output: '{}'".format(
+                    syncd_codename_result['rc'], syncd_codename_result['stdout']))
+        except Exception as e:
+            pytest.fail("Exception while getting debian codename from syncd container: {}".format(str(e)))
+
     pkg_name = py_saithrift_url.split("/")[-1]
+    ip_addr = py_saithrift_url.split("/")[2]
     ptfhost.shell("rm -f {}".format(pkg_name))
+
+    if branch_name.startswith("internal-") and branch_name < "internal-202405":
+        # For internal branches older than 202405, use the original URL without modification
+        pass
+    elif branch_name == "master":
+        py_saithrift_url = (f"http://{ip_addr}/mssonic-public-pipelines/"
+                            f"Azure.sonic-buildimage.official.{asic}/master/{asic}/"
+                            f"latest/target/debs/{debian_codename}/{pkg_name}")
+    else:
+        # For internal branches newer than 202405 and other branches
+        py_saithrift_url = (f"http://{ip_addr}/pipelines/Networking-acs-buildimage-Official/"
+                            f"{asic}/{branch_name}/latest/target/debs/{debian_codename}/{pkg_name}")
+
     # Retry download of saithrift library
     retry_count = 5
     while retry_count > 0:
@@ -335,7 +398,7 @@ def test_update_saithrift_ptf(request, ptfhost):
         retry_count -= 1
 
     if result["failed"] or "OK" not in result["msg"]:
-        pytest.skip("Download failed/error while installing python saithrift package")
+        pytest.fail("Download failed/error while installing python saithrift package: {}".format(py_saithrift_url))
     ptfhost.shell("dpkg -i {}".format(os.path.join("/root", pkg_name)))
     # In 202405 branch, the switch_sai_thrift package is inside saithrift-0.9-py3.11.egg
     # We need to move it out to the correct location