feat: add bunch of ldflags for reproducibility

[developer-guy]

Signed-off-by: Batuhan Apaydın batuhan.apaydin@trendyol.com
cc: @tomhjp 🙋🏻‍♂️

[tomhjp]

Hi @developer-guy, please can you include some documentation and rationale in the Makefile for those options?

[developer-guy]

Hello @tomhjp, I found this:

• -trimpath: increases build reproducibility. Per default full file paths are added to the go binary so two users will very likely have different binaries build even though the code is the same. Important for Reproducible Builds so full build paths and module paths are not embedded.
• -w: No DWARF (reduces binary size)
• -s: No symbol table (even less binary size)
• -znow and -zrelro: Hardening, adds runtime costs. See https://www.redhat.com/en/blog/hardening-elf-binaries-using-relocation-read-only-relro
• -buildmode=pie: enables PIE compilation for binary harderning.
• -mod=readonly: ensure the module files are not updated in any go actions.
• -modcacherw: is not important, but it ensures that go modules creates a write-able path. Default is read-only.

> https://giters.com/ansible/receptor/issues/398

[developer-guy]

And also a bunch of useful articles about reproducible builds for Go binaries:

• https://hackernoon.com/building-reproducible-verifiable-binaries-with-golang
• https://words.filippo.io/reproducing-go-binaries-byte-by-byte/

[developer-guy]

We reduced the binary size up to 4MB 📉

[developer-guy]

Generally speaking; go and build flags is a rabbit hole since Go is unable to parse cli flags and env flags correctly. There is also a difference between hardening flags (PIE and RELRO) and reproducible builds flags. Setting trimpath and unsetting buildid is enough.

thanks to @Foxboron

[developer-guy]

kindly ping @tomhjp

[developer-guy]

kindly ping @tomhjp 🙋🏻‍♂️

[tomhjp]

Hi @developer-guy, please can you put the reasoning in the code alongside/just before the usage?

• -buildid= - I'm not convinced the need for this one is proven. It's set to a hash of the build inputs - that could be stable. Unfortunately I don't have the bandwidth to run experiments around this one
• -s -w - I'm fine with this
• -trimpath LGTM
• -mod=readonly LGTM
• -modcacherw - needs more justification. What paths? And why is it important that they're writeable?

I'm happy to land this either with just the ones that are definitely ok, or you're welcome to argue your case :)

[hashicorp-cla]

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