Optimize "open" method with context manager

Use opening context manager to open a file.

Change-Id: I4744f3e7650d3d3393c5c019216b241ec77710eb

sahara/swift/swift_helper.py

@@ -94,7 +94,8 @@ def _install_ssl_certs(instance, certs):
         "changeit\"")
     with instance.remote() as r:
         for idx, cert in enumerate(certs):
-            data = open(cert).read()
+            with open(cert) as cert_fd:
+                data = cert_fd.read()
             r.write_file_to("/tmp/cert.pem", data)
             try:
                 r.execute_command(register_cmd % idx)

sahara/tests/scenario/base.py

@@ -318,7 +318,8 @@ class BaseTestCase(base.BaseTestCase):
         path = utils.rand_name('test')
         data = None
         if source:
-            data = open(source).read()
+            with open(source) as source_fd:
+                data = source_fd.read()
 
         self.__upload_to_container(container, path, data)
 
@@ -339,7 +340,8 @@ class BaseTestCase(base.BaseTestCase):
             "sudo su - -c \"hdfs dfs -mkdir -p %(path)s \" %(user)s" % {
                 "path": hdfs_dir, "user": hdfs_username})
         hdfs_filepath = utils.rand_name(hdfs_dir + "/file")
-        data = open(source).read()
+        with open(source) as source_fd:
+            data = source_fd.read()
         self._run_command_on_node(
             inst_ip,
             ("echo -e \"%(data)s\" | sudo su - -c \"hdfs dfs"
@@ -350,7 +352,8 @@ class BaseTestCase(base.BaseTestCase):
         return hdfs_filepath
 
     def _create_internal_db_data(self, source):
-        data = open(source).read()
+        with open(source) as source_fd:
+            data = source_fd.read()
         id = self.__create_internal_db_data(utils.rand_name('test'), data)
         return 'internal-db://%s' % id
 

sahara/utils/crypto.py

@@ -49,10 +49,12 @@ def generate_key_pair(key_length=2048):
         processutils.execute(*args)
         if not os.path.exists(keyfile):
             raise ex.SystemError(_("Private key file hasn't been created"))
-        private_key = open(keyfile).read()
+        with open(keyfile) as keyfile_fd:
+            private_key = keyfile_fd.read()
         public_key_path = keyfile + '.pub'
         if not os.path.exists(public_key_path):
             raise ex.SystemError(_("Public key file hasn't been created"))
-        public_key = open(public_key_path).read()
+        with open(public_key_path) as public_key_path_fd:
+            public_key = public_key_path_fd.read()
 
         return private_key, public_key