Flexvolume-driver 0.10.0 logs an empty line alongside each actual log line

Is this a BUG REPORT or FEATURE REQUEST?

BUG REPORT

Versions

CCM Version:

0.10.0

Environment:

• Kubernetes version (use kubectl version):
  1.15.6
• OS (e.g. from /etc/os-release):
  Oracle Linux Server 7.6
• Kernel (e.g. uname -a):
  4.14.35-1844.1.3.el7uek.x86_64
• Others:

What happened?

I see that oci-flexvolume-driver is logging like this:

2020-12-31T16:18:58.739Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully

2020-12-31T16:18:58.739Z	INFO	client/utils.go:94	OCI using read rate limit configuration: QPS=20, bucket=5	{"pid": 26564, "version": "", "build": "", "command": "init"}

2020-12-31T16:18:58.739Z	INFO	client/utils.go:98	OCI using write rate limit configuration: QPS=20, bucket=5	{"pid": 26564, "version": "", "build": "", "command": "init"}

2020-12-31T16:18:58.756Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully

2020-12-31T16:18:58.758Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully

2020-12-31T16:18:58.758Z	INFO	client/utils.go:94	OCI using read rate limit configuration: QPS=20, bucket=5	{"pid": 26571, "version": "", "build": "", "command": "init"}

2020-12-31T16:18:58.758Z	INFO	client/utils.go:98	OCI using write rate limit configuration: QPS=20, bucket=5	{"pid": 26571, "version": "", "build": "", "command": "init"}

2020-12-31T16:18:58.775Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully

2020-12-31T16:18:58.776Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully

Notice the empty lines. I think these empty lines shouldn't be there.
They are then incorrectly tracked by our logging system as a separate event.

What you expected to happen?

I expect it to be like this instead:

2020-12-31T16:18:58.739Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully
2020-12-31T16:18:58.739Z	INFO	client/utils.go:94	OCI using read rate limit configuration: QPS=20, bucket=5	{"pid": 26564, "version": "", "build": "", "command": "init"}
2020-12-31T16:18:58.739Z	INFO	client/utils.go:98	OCI using write rate limit configuration: QPS=20, bucket=5	{"pid": 26564, "version": "", "build": "", "command": "init"}
2020-12-31T16:18:58.756Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully
2020-12-31T16:18:58.758Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully
2020-12-31T16:18:58.758Z	INFO	client/utils.go:94	OCI using read rate limit configuration: QPS=20, bucket=5	{"pid": 26571, "version": "", "build": "", "command": "init"}
2020-12-31T16:18:58.758Z	INFO	client/utils.go:98	OCI using write rate limit configuration: QPS=20, bucket=5	{"pid": 26571, "version": "", "build": "", "command": "init"}
2020-12-31T16:18:58.775Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully
2020-12-31T16:18:58.776Z	INFO	metadata/instance_metadata.go:87	Metadata endpoint /opc/v2/instance/ returned response successfully

How to reproduce it (as minimally and precisely as possible)?

I think this is the standard behavior of oci-flexvolume-driver on any environment, so it should be easy to reproduce

Anything else we need to know?

Start with the oci-flexvolume-driver logging path, focusing on the entries reported from metadata/instance_metadata.go:87 and client/utils.go:94,98. Reproduce the standard behavior described in the issue and trace why an empty line is emitted alongside each log record. Done means the driver emits only the actual log lines without separate empty events.