[runtime] decompress the framework when the size is large (#3820)

FC will compress the framework when it's size is large.
Since we need the FC spec in runtime, decompress here.

Also update the python from 2.7 to 3.7

src/kube-runtime/build/kube-runtime.dockerfile

@@ -27,7 +27,7 @@ COPY GOPATH/src/github.com/microsoft/runtime/ ${PROJECT_DIR}
 RUN ${PROJECT_DIR}/build/runtime/go-build.sh && \
   mv ${PROJECT_DIR}/dist/runtime/ ${INSTALL_DIR}
 
-FROM python:2.7-alpine3.8
+FROM python:3.7-alpine
 
 RUN pip install PyYAML
 

src/kube-runtime/src/init.d/initializer.py

@@ -40,7 +40,7 @@ def run_script(script_path, parameters, plugin_scripts):
         line = proc.stdout.readline()
         if not line:
             break
-        line = line.encode("UTF-8").strip()
+        line = line.decode("utf-8").strip()
         logger.info(line)
     proc.wait()
     if proc.returncode:

src/kube-runtime/src/init.d/parser.py

@@ -18,12 +18,14 @@
 
 from __future__ import print_function
 
-import os
-import sys
+import argparse
+import base64
 import collections
 import logging
-import argparse
+import gzip
 import json
+import os
+import sys
 import yaml
 
 logger = logging.getLogger(__name__)
@@ -33,6 +35,14 @@ def export(k, v):
     print("export {}='{}'".format(k, v))
 
 
+def decompressField(field):
+    if not field:
+        return
+    data = gzip.decompress(base64.b64decode(field))
+    obj = json.loads(data)
+    return obj
+
+
 def generate_runtime_env(framework):
     """Generate runtime env variables for tasks.
 
@@ -68,7 +78,12 @@ def generate_runtime_env(framework):
         }
     logger.info("task roles: {}".format(taskroles))
 
+    # decompress taskRoleStatuses for the large framework
     taskrole_instances = []
+    if not framework["status"]["attemptStatus"]["taskRoleStatuses"]:
+        framework["status"]["attemptStatus"]["taskRoleStatuses"] = decompressField(
+            framework["status"]["attemptStatus"]["taskRoleStatusesCompressed"])
+
     for taskrole in framework["status"]["attemptStatus"]["taskRoleStatuses"]:
         name = taskrole["name"]
         ports = taskroles[name]["ports"]