Merge pull request #650 from Azure/dalbe/cse_shim_1.5.4

CustomScriptExtension shim layer for python interpreter

CustomScript/HandlerManifest.json

@@ -2,11 +2,11 @@
   {
     "version": 1.0,
     "handlerManifest": {
-      "disableCommand": "customscript.py -disable",
-      "enableCommand": "customscript.py -enable",
-      "installCommand": "customscript.py -install",
-      "uninstallCommand": "customscript.py -uninstall",
-      "updateCommand": "customscript.py -update",
+      "disableCommand": "shim.sh -disable",
+      "enableCommand": "shim.sh -enable",
+      "installCommand": "shim.sh -install",
+      "uninstallCommand": "shim.sh -uninstall",
+      "updateCommand": "shim.sh -update",
       "rebootAfterInstall": false,
       "reportHeartbeat": false
     }

CustomScript/customscript.py

@@ -236,14 +236,14 @@ def download_files(hutil):
 def start_daemon(hutil):
     cmd = get_command_to_execute(hutil)
     if cmd:
-        args = [os.path.join(os.getcwd(), __file__), "-daemon"]
+        args = [os.path.join(os.getcwd(), "shim.sh"), "-daemon"]
 
         # This process will start a new background process by calling
-        #     customscript.py -daemon
-        # to run the script and will exit itself immediatelly.
+        #     shim.sh -daemon
+        # to run the script and will exit itself immediately.
 
         # Redirect stdout and stderr to /dev/null. Otherwise daemon process
-        # will throw Broke pipe exeception when parent process exit.
+        # will throw Broke pipe exception when parent process exit.
         devnull = open(os.devnull, 'w')
         subprocess.Popen(args, stdout=devnull, stderr=devnull)
         hutil.do_exit(0, 'Enable', 'transitioning', '0',

CustomScript/manifest.xml

@@ -2,7 +2,7 @@
 <ExtensionImage xmlns="http://schemas.microsoft.com/windowsazure">
   <ProviderNameSpace>Microsoft.OSTCExtensions</ProviderNameSpace>
   <Type>CustomScriptForLinux</Type>
-  <Version>1.5.3</Version>
+  <Version>1.5.4</Version>
   <Label>Microsoft Azure Custom Script Extension for Linux Virtual Machines</Label>
   <HostingResources>VmRole</HostingResources>
   <MediaLink></MediaLink>

CustomScript/shim.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+# The shim scripts provide a single entry point for CSE and will invoke the customscript.py entry point using the
+# appropriate python interpreter version.
+# Arguments passed to the shim layer are redirected to the invoked script without any validation.
+
+COMMAND="./customscript.py"
+PYTHON=""
+ARG="$@"
+
+function find_python(){
+    local python_exec_command=$1
+
+    # Check if there is python defined.
+    if command -v python >/dev/null 2>&1 ; then
+        eval ${python_exec_command}="python"
+    else
+        # Python was not found. Searching for Python3 now.
+        if command -v python >/dev/null 2>&1 ; then
+            eval ${python_exec_command}="python3"
+        fi
+    fi
+}
+
+find_python PYTHON
+
+if [ -z "$PYTHON" ]
+then
+   echo "No Python interpreter found on the box" >&2
+   exit 51 # Not Supported
+else
+    echo "Found: `${PYTHON} --version`"
+fi
+
+${PYTHON} ${COMMAND} ${ARG}
+exit $?
+
+# DONE