[Proposal] Enable CGO as much as possible

[mzz2017]

Proposal

在编译参数 CGO_ENABLED=0 的情况下，lima 虚拟机内的 dae 始终 hang 在：

$ sudo ./dae run -c /etc/dae/config.dae
[Jun 21 02:00:36]  INFO Include config files: [/etc/dae/config.dae]
[Jun 21 02:00:36]  INFO Waiting for network...

编译参数 CGO_ENABLED=1 时一切正常。这可能是 go resolver 不支持 /etc/nsswitch.conf 导致的。

Use Cases

一些特殊场景（例如 DNS 特异环境），提高兼容性。

Potential Benefits

避免一些异常的 go resolver 行为。

Scope

No response

Reference

No response

Implementation

最简单地，可开启 CGO_ENABLED=1，使得 DNS 工作正常：

make CGO_ENABLED=1

这也是打包时的建议方案，因此建议修改 Makefile 默认 CGO_ENABLED=1。

为了提高基础库版本兼容性，可使用 musl-gcc 来尽可能开启 CGO 的情况下保持静态编译：

sudo apt install musl-tools
export CGO_ENABLED=1
export CC=musl-gcc
export BUILD_ARGS='-ldflags "-s -w -linkmode external -extldflags=-static"'
make

$ sudo ./dae run -c /etc/dae/config.dae
[Jun 21 02:25:30]  INFO Include config files: [/etc/dae/config.dae]
[Jun 21 02:25:30]  INFO Waiting for network...
[Jun 21 02:25:31]  INFO Network online.
[Jun 21 02:25:31]  INFO Fetching subscriptions...
[Jun 21 02:25:32]  INFO Loading eBPF programs and maps into the kernel...
[Jun 21 02:25:32]  INFO The loading process takes about 120MB free memory, which will be released after loading. Insufficient memory will cause loading failure.
[Jun 21 02:25:33]  INFO Loaded eBPF programs and maps

CI 里可以利用 zig 编译器来支持交叉编译：https://hrishikeshpathak.com/tips/build-static-binary-cross-compile-cgo-project-zig-compiler/

[dae-prow]

Thanks for opening this issue!