Update for build scripts

It's a shame so much code has to be duplicated. We should probably
extract the build script dance into a crate in the aya repo.

docs/book/programs/cgroup-skb.md

@@ -48,12 +48,6 @@ easily reproduce it in the future by adding the following code:
 
 <!-- markdownlint-disable MD046 -->
 
-=== "xtask/src/codegen.rs"
-
-    ```rust linenums="1"
-    --8<-- "examples/cgroup-skb-egress/xtask/src/codegen.rs"
-    ```
-
 === "xtask/Cargo.toml"
 
     ```toml linenums="1"
@@ -68,8 +62,9 @@ easily reproduce it in the future by adding the following code:
 
 <!-- markdownlint-enable MD046 -->
 
-Once we've generated our file using `cargo xtask codegen` from the root of the
-project, we can access it by including `mod bindings` from eBPF code.
+Once we've generated our file using
+`cargo xtask codegen cgroup-skb-egress-ebpf/src/bindings.rs` we can access it by
+including `mod bindings` from eBPF code.
 
 ## eBPF code
 
@@ -131,7 +126,7 @@ mkdir /sys/fs/cgroup/foo
 Then run the program with:
 
 ```console
-RUST_LOG=info cargo xtask run
+RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"'
 ```
 
 And then, in a separate terminal, as root, try to access `1.1.1.1`:

docs/book/programs/classifiers.md

@@ -88,7 +88,7 @@ is an appropriate type to use in eBPF maps.
 ## Running the program
 
 ```console
-$ RUST_LOG=info cargo xtask run
+$ RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"'
 LOG: SRC 1.1.1.1, ACTION 2
 LOG: SRC 35.186.224.47, ACTION 3
 LOG: SRC 35.186.224.47, ACTION 3

docs/book/programs/lsm.md

@@ -174,7 +174,7 @@ The final result should look like:
 After that, we can build and run our project with:
 
 ```console
-RUST_LOG=info cargo xtask run
+RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"'
 ```
 
 The output should contain our log line showing the PID of the userspace

docs/book/programs/probes.md

@@ -56,7 +56,7 @@ Here's how the code looks like:
 <!-- markdownlint-disable MD013 -->
 
 ```console
-$ RUST_LOG=info cargo xtask run --release
+$ RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"'
 [2022-12-28T20:50:00Z INFO  kprobetcp] Waiting for Ctrl-C...
 [2022-12-28T20:50:05Z INFO  kprobetcp] AF_INET6 src addr: 2001:4998:efeb:282::249, dest addr: 2606:2800:220:1:248:1893:25c8:1946
 [2022-12-28T20:50:11Z INFO  kprobetcp] AF_INET src address: 10.53.149.148, dest address: 10.87.116.72

docs/book/programs/xdp.md

@@ -429,10 +429,8 @@ Let's begin with writing the user-space code:
 ```rust
 use anyhow::Context;
 use aya::{
-    include_bytes_aligned,
     maps::HashMap,
     programs::{Xdp, XdpFlags},
-    Ebpf,
 };
 use aya_log::EbpfLogger;
 use clap::Parser;
@@ -482,14 +480,10 @@ async fn main() -> Result<(), anyhow::Error> {
 
     env_logger::init();
 
-    #[cfg(debug_assertions)]
-    let mut bpf = Ebpf::load(include_bytes_aligned!(
-        "../../target/bpfel-unknown-none/debug/simple-xdp-program"
-    ))?;
-    #[cfg(not(debug_assertions))]
-    let mut bpf = Ebpf::load(include_bytes_aligned!(
-        "../../target/bpfel-unknown-none/release/xdp-simple-xdp-program"
-    ))?;
+    let mut bpf = aya::Ebpf::load(aya::include_bytes_aligned!(concat!(
+        env!("OUT_DIR"),
+        "/simple-xdp-program"
+    )))?;
     if let Err(e) = EbpfLogger::init(&mut bpf) {
         warn!("failed to initialize eBPF logger: {}", e);
     }
@@ -552,10 +546,8 @@ The program awaits the `CTRL+C` signal asynchronously using
 ```rust
 use anyhow::Context;
 use aya::{
-    include_bytes_aligned,
     maps::HashMap,
     programs::{Xdp, XdpFlags},
-    Ebpf,
 };
 use aya_log::EbpfLogger;
 use clap::Parser;
@@ -575,14 +567,10 @@ async fn main() -> Result<(), anyhow::Error> {
 
     env_logger::init();
 
-    #[cfg(debug_assertions)]
-    let mut bpf = Ebpf::load(include_bytes_aligned!(
-        "../../target/bpfel-unknown-none/debug/simple-xdp-program"
-    ))?;
-    #[cfg(not(debug_assertions))]
-    let mut bpf = Ebpf::load(include_bytes_aligned!(
-        "../../target/bpfel-unknown-none/release/xdp-simple-xdp-program"
-    ))?;
+    let mut bpf = aya::Ebpf::load(aya::include_bytes_aligned!(concat!(
+        env!("OUT_DIR"),
+        "/simple-xdp-program"
+    )))?;
     if let Err(e) = EbpfLogger::init(&mut bpf) {
         warn!("failed to initialize eBPF logger: {}", e);
     }
@@ -614,17 +602,18 @@ async fn main() -> Result<(), anyhow::Error> {
 Now that we have all the pieces for our eBPF program, we can run it using:
 
 ```console
-RUST_LOG=info cargo xtask run
+RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"'
 ```
 
 or
 
 ```console
-RUST_LOG=info cargo xtask run -- --iface <interface>
+RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"' -- \
+  --iface <interface>
 ```
 
 if you want to provide another network interface name. note that you can also
-use `cargo xtask run` without the rest, but you won't get any logging.
+omit `RUST_LOG=info`, but you won't get any logging.
 
 [source-code]: https://github.com/aya-rs/book/tree/main/examples/xdp-drop
 [af-xdp]: https://www.kernel.org/doc/html/latest/networking/af_xdp.html

docs/book/start/dropping-packets.md

@@ -69,7 +69,7 @@ Here's how the userspace code looks:
 ## Running the program
 
 ```console
-$ RUST_LOG=info cargo xtask run
+$ RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"'
 [2022-10-04T12:46:05Z INFO  xdp_drop] SRC: 1.1.1.1, ACTION: 1
 [2022-10-04T12:46:05Z INFO  xdp_drop] SRC: 192.168.1.21, ACTION: 2
 [2022-10-04T12:46:05Z INFO  xdp_drop] SRC: 192.168.1.21, ACTION: 2

docs/book/start/hello-xdp.md

@@ -36,7 +36,7 @@ currently looks like this:
 1. Write a log entry every time a packet is received.
 1. This function returns a `Result` that permits all traffic.
 
-Now we can compile this using `cargo xtask build-ebpf`.
+Now we can compile this using `cargo build`.
 
 ### Verifying The Program
 
@@ -141,10 +141,7 @@ Let's look at the details of our generated user-space application:
 Let's try it out!
 
 ```console
-$ cargo xtask run -- -h
-    Finished dev [unoptimized + debuginfo] target(s) in 0.05s
-        Running `target/debug/xtask run -- -h`
-:
+$ cargo run -- -h
     Finished dev [optimized] target(s) in 0.90s
     Finished dev [unoptimized + debuginfo] target(s) in 0.60s
 xdp-hello
@@ -160,11 +157,16 @@ OPTIONS:
 > [!NOTE] Interface Name
 > This command assumes the interface is `eth0` by default. If you wish to
 > attach to an interface with another name, use
-> `RUST_LOG=info cargo xtask run -- --iface wlp2s0`, where  `wlp2s0` is your
-> interface.
+>
+> ```console
+> RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"' -- \
+>   --iface wlp2s0
+> ```
+>
+> where  `wlp2s0` is your interface.
 
 ```console
-$ RUST_LOG=info cargo xtask run
+$ RUST_LOG=info cargo run --config 'target."cfg(all())".runner="sudo -E"'
 [2022-12-21T18:03:09Z INFO  xdp_hello] Waiting for Ctrl-C...
 [2022-12-21T18:03:11Z INFO  xdp_hello] received a packet
 [2022-12-21T18:03:11Z INFO  xdp_hello] received a packet

examples/aya-tool/Cargo.toml

@@ -1,9 +1,9 @@
 [workspace]
-members = ["xtask", "myapp", "myapp-common", "myapp-ebpf"]
+members = ["myapp", "myapp-common", "myapp-ebpf"]
 
 resolver = "2"
 
-default-members = ["xtask", "myapp", "myapp-common"]
+default-members = ["myapp", "myapp-common"]
 
 [profile.release.package.myapp-ebpf]
 debug = 2

examples/aya-tool/README.md

@@ -6,23 +6,10 @@
 1. Install a rust nightly toolchain: `rustup install nightly`
 1. Install bpf-linker: `cargo install bpf-linker`
 
-## Build eBPF
+## Build & Run
 
-```console
-cargo xtask build-ebpf
-```
-
-To perform a release build you can use the `--release` flag.
-You may also change the target architecture with the `--target` flag
-
-## Build Userspace
-
-```console
-cargo build
-```
-
-## Run
+Use `cargo build`, `cargo check`, etc. as normal. Run your program with:
 
-```console
-cargo xtask run
+```shell
+cargo run --config 'target."cfg(all())".runner="sudo -E"'
 ```

examples/aya-tool/myapp-ebpf/Cargo.toml

@@ -8,6 +8,9 @@ aya-ebpf = { git = "https://github.com/aya-rs/aya" }
 aya-log-ebpf = { git = "https://github.com/aya-rs/aya" }
 myapp-common = { path = "../myapp-common" }
 
+[build-dependencies]
+which = { version = "6.0.0", default-features = false }
+
 [[bin]]
 name = "myapp"
 path = "src/main.rs"

examples/aya-tool/myapp-ebpf/build.rs

@@ -0,0 +1,17 @@
+use which::which;
+
+/// Building this crate has an undeclared dependency on the `bpf-linker` binary. This would be
+/// better expressed by [artifact-dependencies][bindeps] but issues such as
+/// https://github.com/rust-lang/cargo/issues/12385 make their use impractical for the time being.
+///
+/// This file implements an imperfect solution: it causes cargo to rebuild the crate whenever the
+/// mtime of `which bpf-linker` changes. Note that possibility that a new bpf-linker is added to
+/// $PATH ahead of the one used as the cache key still exists. Solving this in the general case
+/// would require rebuild-if-changed-env=PATH *and* rebuild-if-changed={every-directory-in-PATH}
+/// which would likely mean far too much cache invalidation.
+///
+/// [bindeps]: https://doc.rust-lang.org/nightly/cargo/reference/unstable.html?highlight=feature#artifact-dependencies
+fn main() {
+    let bpf_linker = which("bpf-linker").unwrap();
+    println!("cargo:rerun-if-changed={}", bpf_linker.to_str().unwrap());
+}

examples/aya-tool/myapp/Cargo.toml

@@ -20,6 +20,22 @@ tokio = { version = "1.25", features = [
 env_logger = "0.11"
 log = "0.4"
 
+[build-dependencies]
+cargo_metadata = { version = "0.18.0", default-features = false }
+# TODO(https://github.com/rust-lang/cargo/issues/12375): this should be an artifact dependency, but
+# it's not possible to tell cargo to use `-Z build-std` to build it. We cargo-in-cargo in the build
+# script to build this, but we want to teach cargo about the dependecy so that cache invalidation
+# works properly.
+#
+# Note also that https://github.com/rust-lang/cargo/issues/10593 occurs when `target = ...` is added
+# to an artifact dependency; it seems possible to work around that by setting `resolver = "1"` in
+# Cargo.toml in the workspace root.
+#
+# Finally note that *any* usage of `artifact = ...` in *any* Cargo.toml in the workspace breaks
+# workflows with stable cargo; stable cargo outright refuses to load manifests that use unstable
+# features.
+myapp-ebpf = { path = "../myapp-ebpf" }
+
 [[bin]]
 name = "myapp"
 path = "src/main.rs"