feat: SingularityCE: looking for the platform-aware image in CVMFS lo…

…cation

src/DIRAC/Core/Utilities/File.py

@@ -4,15 +4,16 @@
    By default on Error they return None.
 """
 
-import os
+import errno
+import glob
 import hashlib
+import os
 import random
-import glob
-import sys
 import re
-import errno
 import stat
+import sys
 import tempfile
+import threading
 from contextlib import contextmanager
 
 # Translation table of a given unit to Bytes
@@ -277,6 +278,32 @@ def secureOpenForWrite(filename=None, *, text=True):
         yield fd, filename
 
 
+def safe_listdir(directory, timeout=60):
+    """This is a "safe" list directory,
+    for lazily-loaded File Systems like CVMFS.
+    There's by default a 60 seconds timeout.
+
+    :param str directory: directory to list
+    :param int timeout: optional timeout, in seconds. Defaults to 60.
+    """
+
+    def listdir(directory):
+        try:
+            return os.listdir(directory)
+        except FileNotFoundError:
+            print(f"{directory} not found")
+            return []
+
+    contents = []
+    t = threading.Thread(target=lambda: contents.extend(listdir(directory)))
+    t.daemon = True  # don't delay program's exit
+    t.start()
+    t.join(timeout)
+    if t.is_alive():
+        return None  # timeout
+    return contents
+
+
 if __name__ == "__main__":
     for p in sys.argv[1:]:
         print(f"{p} : {getGlobbedTotalSize(p)} bytes")

src/DIRAC/Core/Utilities/Os.py

@@ -3,12 +3,14 @@
    by default on Error they return None
 """
 import os
+import platform
 import shutil
 
 import DIRAC
+from DIRAC.Core.Utilities import List
 from DIRAC.Core.Utilities.Decorators import deprecated
+from DIRAC.Core.Utilities.File import safe_listdir
 from DIRAC.Core.Utilities.Subprocess import shellCall, systemCall
-from DIRAC.Core.Utilities import List
 
 DEBUG = 0
 
@@ -147,6 +149,52 @@ def sourceEnv(timeout, cmdTuple, inputEnv=None):
     return result
 
 
-@deprecated("Will be removed in DIRAC 8.1", onlyOnce=True)
+@deprecated("Will be removed in DIRAC 9.0", onlyOnce=True)
 def which(executable):
     return shutil.which(executable)
+
+
+def findImage(technology="apptainer", operating_system="alma9"):
+    """Finds the image for the current platform
+    
+       This looks into location "${CVMFS_locations}/container/${technology}/${operating_system}/${platform}/"
+       and expects to find one of the following platforms:
+       - x86_64
+       - aarch64
+       - ppc64le
+
+    """
+    from DIRAC.ConfigurationSystem.Client.Helpers.Operations import Operations
+
+    plat = DIRAC.gConfig.getValue("LocalSite/Platform", platform.machine())
+    DIRAC.gLogger.info(f"Platform: {plat}")
+
+    # NB: platform compatibility is more complex than the following simple identification. 
+    # sources: 
+    # https://stackoverflow.com/questions/45125516/possible-values-for-uname-m
+    # https://en.wikipedia.org/wiki/Uname
+
+    if plat.lower() == "amd64":
+        plat = "x86_64"
+    if plat.lower().startswith("arm"):
+        plat = "aarch64"
+    if plat.lower().startswith("ppc64"):
+        plat = "ppc64le"
+
+    if plat not in ["x86_64", "aarch64", "ppc64le"]:
+        DIRAC.gLogger.error(f"Platform {plat} not supported")
+        return None
+
+    CVMFS_locations = DIRAC.gConfig.getValue(
+        "LocalSite/CVMFS_locations", Operations().getValue("Pilot/CVMFS_locations", [])
+    )
+
+    rootImage = None
+
+    for candidate in CVMFS_locations:
+        rootImage = os.path.join(candidate, "container", technology, operating_system, plat)
+        DIRAC.gLogger.verbose(f"Checking {rootImage} existence")
+        if safe_listdir(rootImage):
+            break
+
+    return rootImage

src/DIRAC/Core/scripts/dirac_apptainer_exec.py

@@ -0,0 +1,85 @@
+""" Starts a DIRAC command inside an apptainer container.
+"""
+
+import os
+import shutil
+import sys
+
+import DIRAC
+from DIRAC import S_ERROR, gLogger
+from DIRAC.Core.Base.Script import Script
+from DIRAC.Core.Utilities.Os import findImage
+from DIRAC.Core.Utilities.Subprocess import systemCall
+
+CONTAINER_WRAPPER = """#!/bin/bash
+
+echo "Starting inner container wrapper scripts (no install) at `date`."
+export DIRAC=%(dirac_env_var)s
+export DIRACOS=%(diracos_env_var)s
+# In any case we need to find a bashrc, and a cfg
+source %(rc_script)s
+%(command)s
+echo "Finishing inner container wrapper scripts at `date`."
+"""
+
+CONTAINER_DEFROOT = "/cvmfs/dirac.egi.eu/container/apptainer/alma9/x86_64"
+
+
+def getEnv():
+    """Gets the environment for use within the container.
+    We blank almost everything to prevent contamination from the host system.
+    """
+
+    payloadEnv = {k: v for k, v in os.environ.items()}
+    payloadEnv["TMP"] = "/tmp"
+    payloadEnv["TMPDIR"] = "/tmp"
+    payloadEnv["X509_USER_PROXY"] = os.path.join("tmp", "proxy")
+    payloadEnv["DIRACSYSCONFIG"] = os.path.join("tmp", "dirac.cfg")
+
+    return payloadEnv
+
+
+@Script()
+def main():
+    Script.registerArgument(" command: Command to execute inside the container")
+    command = Script.getPositionalArgs(group=True)
+
+    wrapSubs = {
+        "dirac_env_var": os.environ.get("DIRAC", os.getcwd()),
+        "diracos_env_var": os.environ.get("DIRACOS", os.getcwd()),
+    }
+    wrapSubs["rc_script"] = os.path.join(os.path.realpath(sys.base_prefix), "diracosrc")
+    wrapSubs["command"] = command
+    shutil.copyfile("dirac.cfg", os.path.join("tmp", "dirac.cfg"))
+
+    wrapLoc = os.path.join("tmp", "dirac_container.sh")
+    rawfd = os.open(wrapLoc, os.O_WRONLY | os.O_CREAT, 0o700)
+    fd = os.fdopen(rawfd, "w")
+    fd.write(CONTAINER_WRAPPER % wrapSubs)
+    fd.close()
+
+    innerCmd = os.path.join("tmp", "dirac_container.sh")
+    cmd = ["apptainer", "exec"]
+    cmd.extend(["--contain"])  # use minimal /dev and empty other directories (e.g. /tmp and $HOME)
+    cmd.extend(["--ipc"])  # run container in a new IPC namespace
+    cmd.extend(["--workdir", "/tmp"])  # working directory to be used for /tmp, /var/tmp and $HOME
+    cmd.extend(["--home", "/tmp"])  # Avoid using small tmpfs for default $HOME and use scratch /tmp instead
+    cmd.extend(["--bind", "{0}:{0}:ro".format(os.path.join(os.path.realpath(sys.base_prefix)))])
+
+    rootImage = findImage() or CONTAINER_DEFROOT
+
+    if os.path.isdir(rootImage) or os.path.isfile(rootImage):
+        cmd.extend([rootImage, innerCmd])
+    else:
+        # if we are here is because there's no image, or it is not accessible (e.g. not on CVMFS)
+        gLogger.error("Apptainer image to exec not found: ", rootImage)
+        return S_ERROR("Failed to find Apptainer image to exec")
+
+    gLogger.debug(f"Execute Apptainer command: {cmd}")
+    result = systemCall(0, cmd, env=getEnv())
+    if not result["OK"]:
+        DIRAC.exit(1)
+
+
+if __name__ == "__main__":
+    main()

src/DIRAC/Resources/Computing/SingularityComputingElement.py

@@ -11,8 +11,6 @@
     See the Configuration/Resources/Computing documention for details on
     where to set the option parameters.
 """
-
-import io
 import json
 import os
 import re
@@ -21,7 +19,8 @@
 import tempfile
 
 import DIRAC
-from DIRAC import S_OK, S_ERROR, gConfig, gLogger
+from DIRAC import S_ERROR, S_OK, gConfig, gLogger
+from DIRAC.Core.Utilities.Os import findImage
 from DIRAC.Core.Utilities.Subprocess import systemCall
 from DIRAC.ConfigurationSystem.Client.Helpers import Operations
 from DIRAC.Core.Utilities.ThreadScheduler import gThreadScheduler
@@ -30,7 +29,8 @@
 from DIRAC.WorkloadManagementSystem.Utilities.Utils import createRelocatedJobWrapper
 
 # Default container to use if it isn't specified in the CE options
-CONTAINER_DEFROOT = "/cvmfs/cernvm-prod.cern.ch/cvm4"
+CONTAINER_DEFROOT = "/cvmfs/dirac.egi.eu/container/apptainer/alma9/x86_64"
+CONTAINER_DEFOS = "alma9"
 CONTAINER_WORKDIR = "DIRAC_containers"
 CONTAINER_INNERDIR = "/tmp"
 
@@ -107,9 +107,6 @@ def __init__(self, ceUniqueID):
         super().__init__(ceUniqueID)
         self.__submittedJobs = 0
         self.__runningJobs = 0
-        self.__root = CONTAINER_DEFROOT
-        if "ContainerRoot" in self.ceParameters:
-            self.__root = self.ceParameters["ContainerRoot"]
         self.__workdir = CONTAINER_WORKDIR
         self.__innerdir = CONTAINER_INNERDIR
         self.__singularityBin = "singularity"
@@ -147,7 +144,7 @@ def __hasSingularity(self):
                 self.log.debug(f'Use singularity from "{self.__singularityBin}"')
                 return True
         if "PATH" not in os.environ:
-            return False  # Hmm, PATH not set? How unusual...
+            return False  # PATH might not be set (e.g. HTCondorCE)
         searchPaths = os.environ["PATH"].split(os.pathsep)
         # We can use CVMFS as a last resort if userNS is enabled
         if self.__hasUserNS():
@@ -359,8 +356,6 @@ def submitJob(self, executableFile, proxy=None, **kwargs):
 
         :return: S_OK(payload exit code) / S_ERROR() if submission issue
         """
-        rootImage = self.__root
-        renewTask = None
         # Check that singularity is available
         if not self.__hasSingularity():
             self.log.error("Singularity is not installed on PATH.")
@@ -375,6 +370,7 @@ def submitJob(self, executableFile, proxy=None, **kwargs):
         baseDir = ret["baseDir"]
         tmpDir = ret["tmpDir"]
 
+        renewTask = False
         if proxy:
             payloadProxyLoc = ret["proxyLocation"]
 
@@ -449,10 +445,14 @@ def submitJob(self, executableFile, proxy=None, **kwargs):
             containerOpts = self.ceParameters["ContainerOptions"].split(",")
             for opt in containerOpts:
                 cmd.extend([opt.strip()])
-        if os.path.isdir(rootImage) or os.path.isfile(rootImage):
+
+        container_operating_system = self.ceParameters.get("ContainerOS") or CONTAINER_DEFOS
+        rootImage = findImage(operating_system=container_operating_system) or self.ceParameters.get("ContainerRoot") or CONTAINER_DEFROOT
+
+        if rootImage and os.path.isdir(rootImage) or os.path.isfile(rootImage):
             cmd.extend([rootImage, innerCmd])
         else:
-            # if we are here is because there's no image, or it is not accessible (e.g. not on CVMFS)
+            # if we are here it is because there's no image, or it is not accessible (e.g. not on CVMFS)
             self.log.error("Singularity image to exec not found: ", rootImage)
             return S_ERROR("Failed to find singularity image to exec")