68 lines
2.6 KiB
Text
68 lines
2.6 KiB
Text
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= 2: Rust
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:page-pagination:
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This sample assumes you've tried the Go example, as the Rust implementation of
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these concepts work identically. This example dives into the details of the
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overrides, which are necessary to run Rust builds in a minimal sandbox.
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Most Rust projects depend on external dependencies, written in e.g. C, and
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cannot be compiled with purely `rustc` inside a sandbox. To allow for this,
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Zilch's Rust support has been designed with this fact in mind.
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If we try to compile the example in this directory as-is, it fails, as the
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crate depends on `pyo3`, which depends on a working Python interpreter:
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[,console]
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----
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$ zilch-cli-rust -m examples/rust
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…
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Error: (error Error 0 builder for '/nix/store/n5l4w8m3fj3m1s06p75r0pqj8s9l8cmf-build.rs-run.drv' failed with exit code 101;
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last 17 log lines:
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> error: no Python 3.x interpreter found
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…
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> Package: pyo3-build-config
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> note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
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----
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To fix this, we'll need to write an override file. This file describes to Zilch
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how to override the Rust environment. There's three override points, as described
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in xref:rust/usage.adoc[the more direct usage file]. We'll only use `buildScript`
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here, as `pyo3` is simple. Looking at the code, it seems that it expects a `python3`
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on `PATH`. To do this, we just need to write a fragment for that. Zilch knows how
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to append to these variables, so all we need is a file that contains the following:
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.zilch-override.json
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[,json]
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----
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{
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"pyo3-build-config": {
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"buildScript": {
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"PATH": "${pkgs.python3}/bin"
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}
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}
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}
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----
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Now, when the `build.rs` for `pyo3-build-config` is run, it will have `python3`
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available to it. The output that this build script generates, which is stored
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in the Nix store, also has references to the parts of `python3` that the build
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script used, ensuring that it is properly passed through to the crates that, in
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turn, depend on this build script; and the final binary has references to not
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just libc, but also python3:
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[,console]
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----
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$ zilch-cli-rust -m examples/rust -z override.json
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zilch-pyo3-example zilch_pyo3_example bin /nix/store/vqpj68dgswf8v64sq45banq6vn0fshnz-rustc-bin-zilch_pyo3_example-link
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$ nix-store -qR /nix/store/vqpj68dgswf8v64sq45banq6vn0fshnz-rustc-bin-zilch_pyo3_example-link | grep python
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/nix/store/cfapjd2rvqrpry4grb0kljnp8bvnvfxz-python3-3.13.8
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# hooray!
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----
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Zilch ships with a series of overrides, primarily around what I (the developer)
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have come across. Some of these also use a helper that Zilch provides, which
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sets up `pkg-config` based packages recursively, the same way Nixpkgs does.
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