From 2a6d2a6402e40e2a25b812bfb659824ab83fcec6 Mon Sep 17 00:00:00 2001
From: Tamir Duberstein <tamird@gmail.com>
Date: Fri, 14 Jul 2023 18:15:10 -0400
Subject: [PATCH 1/2] integration-test: transitive dep on Rust ebpf

Emit "cargo:rerun-if-changed={}" for each transitive dependency on
integration-ebpf. In a normal world we'd just add integration-ebpf to
our build-dependencies, but cargo ignores this because integration-ebpf
has no library targets.
---
 test/integration-test/build.rs | 52 ++++++++++++++++++++++++----------
 1 file changed, 37 insertions(+), 15 deletions(-)

diff --git a/test/integration-test/build.rs b/test/integration-test/build.rs
index 3d9fa08e..7a802748 100644
--- a/test/integration-test/build.rs
+++ b/test/integration-test/build.rs
@@ -1,4 +1,5 @@
 use std::{
+    collections::{HashMap, HashSet},
     env,
     ffi::OsString,
     fmt::Write as _,
@@ -9,7 +10,7 @@ use std::{
 };
 
 use cargo_metadata::{
-    Artifact, CompilerMessage, Message, Metadata, MetadataCommand, Package, Target,
+    Artifact, CompilerMessage, Dependency, Message, Metadata, MetadataCommand, Package, Target,
 };
 
 fn main() {
@@ -25,6 +26,17 @@ fn main() {
         }
     };
 
+    const INTEGRATION_EBPF_PACKAGE: &str = "integration-ebpf";
+
+    let Metadata { packages, .. } = MetadataCommand::new().no_deps().exec().unwrap();
+    let packages: HashMap<String, _> = packages
+        .into_iter()
+        .map(|package| {
+            let Package { name, .. } = &package;
+            (name.clone(), package)
+        })
+        .collect();
+
     let manifest_dir = env::var_os("CARGO_MANIFEST_DIR").unwrap();
     let manifest_dir = PathBuf::from(manifest_dir);
     let out_dir = env::var_os("OUT_DIR").unwrap();
@@ -117,14 +129,29 @@ fn main() {
             }
         }
 
-        let ebpf_dir = manifest_dir.parent().unwrap().join("integration-ebpf");
-        println!("cargo:rerun-if-changed={}", ebpf_dir.to_str().unwrap());
-
         let target = format!("{target}-unknown-none");
 
+        // Teach cargo about our dependencies.
+        let mut visited = HashSet::new();
+        let mut frontier = vec![INTEGRATION_EBPF_PACKAGE];
+        while let Some(package) = frontier.pop() {
+            if !visited.insert(package) {
+                continue;
+            }
+            let Package { dependencies, .. } = packages.get(package).unwrap();
+            for Dependency { name, path, .. } in dependencies {
+                if let Some(path) = path {
+                    println!("cargo:rerun-if-changed={}", path.as_str());
+                    frontier.push(name);
+                }
+            }
+        }
+
         let mut cmd = Command::new("cargo");
-        cmd.current_dir(&ebpf_dir).args([
+        cmd.args([
             "build",
+            "-p",
+            "integration-ebpf",
             "-Z",
             "build-std=core",
             "--release",
@@ -185,18 +212,13 @@ fn main() {
             fs::write(&dst, []).unwrap_or_else(|err| panic!("failed to create {dst:?}: {err}"));
         }
 
-        let Metadata { packages, .. } = MetadataCommand::new().no_deps().exec().unwrap();
-        for Package { name, targets, .. } in packages {
-            if name != "integration-ebpf" {
+        let Package { targets, .. } = packages.get(INTEGRATION_EBPF_PACKAGE).unwrap();
+        for Target { name, kind, .. } in targets {
+            if *kind != ["bin"] {
                 continue;
             }
-            for Target { name, kind, .. } in targets {
-                if kind != ["bin"] {
-                    continue;
-                }
-                let dst = out_dir.join(name);
-                fs::write(&dst, []).unwrap_or_else(|err| panic!("failed to create {dst:?}: {err}"));
-            }
+            let dst = out_dir.join(name);
+            fs::write(&dst, []).unwrap_or_else(|err| panic!("failed to create {dst:?}: {err}"));
         }
     }
 }

From 581d5c8f5f73b0fff553279ba8e848d407be2291 Mon Sep 17 00:00:00 2001
From: Tamir Duberstein <tamird@gmail.com>
Date: Fri, 14 Jul 2023 18:18:57 -0400
Subject: [PATCH 2/2] integration-test: bust cache on bpf-linker

This is useful when iterating on bpf-linker locally, which is otherwise
an undeclared input to this build.

We could use an artifact dependency[0] here, but they are unstable and
bpf-linker requires gymnastics to build correctly (for now).

[0] https://doc.rust-lang.org/cargo/reference/unstable.html#artifact-dependencies-dependency-declarations
---
 test/integration-test/Cargo.toml | 3 ++-
 test/integration-test/build.rs   | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/test/integration-test/Cargo.toml b/test/integration-test/Cargo.toml
index 8fb11bda..82ccfcdf 100644
--- a/test/integration-test/Cargo.toml
+++ b/test/integration-test/Cargo.toml
@@ -24,4 +24,5 @@ tokio = { version = "1.24", default-features = false, features = [
 ] }
 
 [build-dependencies]
-cargo_metadata = "0.15.4"
+cargo_metadata = { version = "0.15.4", default-features = false }
+which = { version = "4.4.0", default-features = false }
diff --git a/test/integration-test/build.rs b/test/integration-test/build.rs
index 7a802748..8f5596f0 100644
--- a/test/integration-test/build.rs
+++ b/test/integration-test/build.rs
@@ -12,6 +12,7 @@ use std::{
 use cargo_metadata::{
     Artifact, CompilerMessage, Dependency, Message, Metadata, MetadataCommand, Package, Target,
 };
+use which::which;
 
 fn main() {
     const AYA_BUILD_INTEGRATION_BPF: &str = "AYA_BUILD_INTEGRATION_BPF";
@@ -147,6 +148,9 @@ fn main() {
             }
         }
 
+        let bpf_linker = which("bpf-linker").unwrap();
+        println!("cargo:rerun-if-changed={}", bpf_linker.to_str().unwrap());
+
         let mut cmd = Command::new("cargo");
         cmd.args([
             "build",