Add Python script to balance Docker plays amongst shards

util/balancecontainers.py

+import yaml
+import os
+import pathlib2
+import itertools
+import sys
+
+class ContainerBalancer:
+
+    def __init__(self):
+        self.load_repo_path()
+
+    def load_repo_path(self):
+        """Loads the path for the configuration repository from TRAVIS_BUILD_DIR environment variable."""
+
+        if os.environ.get("TRAVIS_BUILD_DIR"):
+            self.repo_path = os.environ.get("TRAVIS_BUILD_DIR")
+        else:
+            raise EnvironmentError("TRAVIS_BUILD_DIR environment variable is not set.")
+
+    def pack_containers(self, containers):
+
+        num_shards = 3
+
+        config_file_path = pathlib2.Path(self.repo_path, "util", "parsefiles_config.yml")
+
+        with config_file_path.open() as config_file:
+                config = yaml.load(config_file)
+
+        weights = config.get("weights")
+
+        weights_list = [x.items() for x in weights]
+        weights_list = list(itertools.chain.from_iterable(weights_list))
+
+        used_containers = [x for x in weights_list if x[0] in containers]
+
+        sorted_containers = sorted(used_containers, key = lambda x: x[1], reverse=True) 
+
+        shards = []
+
+        for i in range(0, num_shards):
+            shards.append({"containers": [], "sum": 0})
+
+        for container in sorted_containers:
+            # shard with minimum execution time
+            shard = min(shards, key = lambda x: x["sum"])
+
+            shard["containers"].append(container)
+            shard["sum"] += container[1]
+
+        return shards
+
+if __name__ == '__main__':
+
+    balancer = ContainerBalancer()
+
+    containers = []
+
+    for line in sys.stdin:
+        line = line.strip()
+        line = line.strip("[]")
+
+        items = line.split()
+        containers.extend(items)
+
+    # containers = {"discovery":6, "go-agent": 3, "xqwatcher": 3, "analytics_api": 1, "edxapp": 28, 
+                  # "insights": 4, "credentials":8, "forum": 7, "nginx":1, "xqueue":2}
+
+    # containers = ["discovery", "go-agent", "xqwatcher", "analytics_api", "edxapp", "insights", "credentials", "forum", "nginx", "xqueue"]
+    # containers = ["discovery", "go-agent", "xqwatcher", "analytics_api", "insights", "credentials", "forum", "nginx", "xqueue"]
+    # [discovery go-agent xqwatcher analytics_api edxapp insights credentials forum nginx xqueue]
+
+
+    shards = balancer.pack_containers(containers)
+
+    for shard in shards:
+        middle = " "
+
+        conts = [x[0] for x in shard["containers"]]
+
+        line = middle.join(conts)
+        print line
+
+    # for shard in shards:
+    #         for container in shard["containers"]:
+    #             print container[0],
+    #         print ""
+
+    # containers.sort(reverse=True)
+
+
+ # a={"discovery":6, "go-agent": 3, "xqwatcher": 3, "analytics_api": 1, "edxapp": 28, "insights": 4, "credentials":8, "forum":"nginx":1, "xqueue":2, "trusty-common":5, "precise-common":4}
\ No newline at end of file