mirror of
https://github.com/clockworklabs/SpacetimeDB.git
synced 2026-05-12 18:57:51 -04:00
Phoebe Goldman
7345296cc9
# Description of Changes When building under Nix, Git metadata is not available within the sandbox, as we use `lib.cleanSource` on our source directory. This is important because it avoids spurious rebuilds and/or determinism hazards. The build was broken due to our new `spacetime init` template system accessing Git metadata in the CLI's build.rs to filter out non-git-tracked files from the templates. The Flake sandbox does this automatically (even without `lib.cleanSource`!), so when building under Nix it's unnecessary to do twice. (I remain unconvinced that it's necessary to do in non-Nix builds either, as CI builds should have a clean checkout and local dev builds don't need clean templates, but the behavior was already in master and I didn't feel comfortable removing it.) As an enhancement, I've also found a Nix-ey way to embed our Git commit hash in builds. Previously, builds under Nix had the empty string instead of a commit hash, because we included the `git` CLI tool but scrubbed the necessary metadata. Now, we inject an environment variable from the Nix flake, and don't make the `git` CLI tool available at all. This has the convenient upside of allowing Nix builds to reference `dirtyRev` in builds with a dirty worktree, which should reduce confusion. # API and ABI breaking changes N/a # Expected complexity level and risk 3? I didn't have a strong understanding of what the CLI build script was doing, and to what extent it was doing things intentionally versus for convenience. As such, it's possible that I've inadvertently damaged something load-bearing. # Testing - [x] Built with `nix build`, ran `spacetime init`, chose the `basic-rust` template, and got a reasonable-looking template instantiation. - [ ] Hopefully we have automated tests for this?
40 lines
1.5 KiB
Rust
40 lines
1.5 KiB
Rust
use std::process::Command;
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// https://stackoverflow.com/questions/43753491/include-git-commit-hash-as-string-into-rust-program
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#[allow(clippy::disallowed_macros)]
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fn main() {
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let git_hash = find_git_hash();
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println!("cargo:rustc-env=GIT_HASH={git_hash}");
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}
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fn nix_injected_commit_hash() -> Option<String> {
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use std::env::VarError;
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// Our flake.nix sets this environment variable to be our git commit hash during the build.
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// This is important because git metadata is otherwise not available within the nix build sandbox,
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// and we don't install the git command-line tool in our build.
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match std::env::var("SPACETIMEDB_NIX_BUILD_GIT_COMMIT") {
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Ok(commit_sha) => {
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// Var is set, we're building under Nix.
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Some(commit_sha)
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}
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Err(VarError::NotPresent) => {
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// Var is not set, we're not in Nix.
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None
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}
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Err(VarError::NotUnicode(gross)) => {
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// Var is set but is invalid unicode, something is very wrong.
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panic!("Injected commit hash is not valid unicode: {gross:?}")
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}
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}
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}
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fn find_git_hash() -> String {
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nix_injected_commit_hash().unwrap_or_else(|| {
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// When we're *not* building in Nix, we can assume that git metadata is still present in the filesystem,
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// and that the git command-line tool is installed.
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let output = Command::new("git").args(["rev-parse", "HEAD"]).output().unwrap();
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String::from_utf8(output.stdout).unwrap().trim().to_string()
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})
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}
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