No debug info when building Kubernetes source code with make all GOGCFLAGS="-N -l"

[qianzhangxa]

What happened:
I ran make all GOGCFLAGS="-N -l" to build latest Kubernetes source code, and then I see the binaries are still stripped:

$ file _output/bin/kubelet 
_output/bin/kubelet: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=715f57807e652488c5e086b82f5daf4063a74b04, stripped

And I can not use dlv to debug the binary:

$ dlv exec _output/bin/kubelet                          
could not launch process: could not open debug info

In Makefile, I see the following comments:

#   make all GOGCFLAGS="-N -l"
#     Note: Use the -N -l options to disable compiler optimizations an inlining.
#           Using these build options allows you to subsequently use source
#           debugging tools like delve.

But that seems not correct in my build.

What you expected to happen:
I expected Kubernetes binaries with debug info.

How to reproduce it (as minimally and precisely as possible):
make all GOGCFLAGS="-N -l"

Anything else we need to know?:

Environment:

• Kubernetes version (use kubectl version): Latest Kubernetes source code.
• Cloud provider or hardware configuration: A virtual machine with 2 cores and 8GB RAM.
• OS (e.g: cat /etc/os-release): 18.04 LTS (Bionic Beaver)
• Kernel (e.g. uname -a): Linux workstation 4.15.0-23-generic Change 'this' varable to more sensible abbreviation #25-Ubuntu SMP Wed May 23 18:02:16 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
• Install tools:
• Network plugin and version (if this is a network-related bug):
• Others:

[qianzhangxa]

/sig release

[YoubingLi]

It is the problem of "-ldflags -s -w" and I will provide a PR ASAP.

/cc @YoubingLi

[dims]

@YoubingLi @qianzhangxa please set GOLDFLAGS to an empty string and see if that helps

7e01702

[YoubingLi]

@dims
Yes, this is my fix solution (Remove '-s -w' from goldflags).
Meanwhile, I had verified that it works.

[qianzhangxa]

@dims @YoubingLi I tried make all GOGCFLAGS="-N -l" GOLDFLAGS="" and it works! So I think the comments in the Makefile need to be updated a bit since only GOGCFLAGS="-N -l" is not enough for debugger to debug Kubernetes binaries.

[YoubingLi]

@qianzhangxa

It should work after you explicitly specify GOLDFLAGS="" in command line.

If GOLDFLAGS is not specified, the default value is "-w -s". It turns out all binaries are built as stripped.

[dims]

@qianzhangxa @YoubingLi yes, please update comments in the Makefile to make all GOGCFLAGS="-N -l" GOLDFLAGS=""

[Davidrjx]

in my case for kubernetes1.13.5, removing '-s -w' from goldflags is enough.