kapacitor: fix build for Linux

[cho-m]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

---

https://github.com/Homebrew/homebrew-core/runs/3158668157?check_suite_focus=true

go: downloading sigs.k8s.io/yaml v1.2.0
# pkg-config --cflags  -- flux
Started pkg-config	{"arg0": "/tmp/kapacitor-20210726-8467-1qvlnnn/bootstrap/pkg-config", "args": ["--cflags", "--", "flux"]}
Could not find pkg-config executable	{"path": "/home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/shims/linux/super:/home/linuxbrew/.linuxbrew/opt/go/bin:/home/linuxbrew/.linuxbrew/opt/rust/bin:/usr/bin:/bin:/usr/sbin:/sbin", "error": "exec: \"pkg-config\": executable file not found in $PATH"}
pkg-config: exit status 1

[cho-m]

Not sure why this didn't get tested during Rust 1.54 bump, but seems to not build due to the old flux dependency in go.mod.

   Compiling serde-aux v0.6.1
   Compiling flux-core v0.4.0 (/Users/brew/Library/Caches/Homebrew/go_cache/pkgconfig/github.com/influxdata/flux@v0.116.1-0.20210519190248-4347b978c91a/libflux/flux-core)
   Compiling tera v1.8.0
error: field is never read: `message`
  --> flux-core/src/parser/mod.rs:35:5
   |
35 |     pub message: String,
   |     ^^^^^^^^^^^^^^^^^^^
   |

[danielnachun]

Has upstream been notified that they need to update flux? I'm not sure if we were doing that for other formulae that had this issue.

[cho-m]

We can open an issue/PR to request an update, though the upstream org (InfluxData) is the maintainer of both projects, so I would hope they are already aware of it.

Not sure if we have examples in Go, but we do modify Rust projects Cargo.lock dependencies when necessary. Though, I am not sure if we have a standard way to go about this.

The only options here to fix build would be to modify go.mod to either a much newer version (v0.124 thru v0.126), or just patch the specific problem like shown. EDIT: Or, I guess use rustup to install older Rust.

[SMillerDev]

We should really create an issue upstream too if we're going to patch this.

[cho-m]

I'll open an issue upstream as I didn't see anything specific to flux

However, I did find that upstream is looking into locking Rust version, e.g. influxdata/kapacitor#2600, which may mean they aren't going to support newer flux (Rust 1.54) for now.

Not sure if we would prefer the workaround of swapping rust with rustup-init + previous stable Rust (1.53.x).

[cho-m]

Upstream issue influxdata/kapacitor#2612
I'll add in a comment.

Now, the question is whether to use:

• current patch on flux
• switch rust to rustup-init and do something like

      system Formula["rustup-init"].bin/"rustup-init", "-qy", "--no-modify-path",
             "--default-toolchain", "stable-1.53.0", "--profile", "minimal"
      ENV.prepend_path PATH, HOMEBREW_CACHE/"cargo_cache/bin"

[SMillerDev]

I don't like it, but I think it's the best of two evils.

[cho-m]

The build is probably broken again due to go update to 1.17 based on how flux needed fix in #84002

I'll probably rebase and re-run CI to confirm.

Similar situation to Rust where either need to patch or need to switch to go@1.16 (#84073)

[cho-m]

Actually didn't hit an issue after rebase, so should be fine to merge

[BrewTestBot]

@carlocab has triggered a merge.