//! This module contains glue code translating from
//! [nix_compat::derivation::Derivation] to [tvix_build::proto::BuildRequest].
use std::collections::{BTreeMap, BTreeSet};
use bytes::Bytes;
use nix_compat::{derivation::Derivation, nixbase32};
use sha2::{Digest, Sha256};
use tvix_build::proto::{
build_request::{AdditionalFile, BuildConstraints, EnvVar},
BuildRequest,
};
use tvix_castore::proto::{self, node::Node};
/// These are the environment variables that Nix sets in its sandbox for every
/// build.
const NIX_ENVIRONMENT_VARS: [(&str, &str); 12] = [
("HOME", "/homeless-shelter"),
("NIX_BUILD_CORES", "0"), // TODO: make this configurable?
("NIX_BUILD_TOP", "/"),
("NIX_LOG_FD", "2"),
("NIX_STORE", "/nix/store"),
("PATH", "/path-not-set"),
("PWD", "/build"),
("TEMP", "/build"),
("TEMPDIR", "/build"),
("TERM", "xterm-256color"),
("TMP", "/build"),
("TMPDIR", "/build"),
];
/// Takes a [Derivation] and turns it into a [BuildRequest].
/// It assumes the Derivation has been validated.
/// It needs two lookup functions:
/// - one translating input sources to a castore node
/// (`fn_input_sources_to_node`)
/// - one translating a tuple of drv path and (a subset of their) output names to
/// castore nodes of the selected outpus (`fn_input_drvs_to_output_nodes`).
#[allow(clippy::mutable_key_type)]
pub(crate) fn derivation_to_build_request(
derivation: &Derivation,
inputs: BTreeSet<Node>,
) -> std::io::Result<BuildRequest> {
debug_assert!(derivation.validate(true).is_ok(), "drv must validate");
// produce command_args, which is builder and arguments in a Vec.
let mut command_args: Vec<String> = Vec::with_capacity(derivation.arguments.len() + 1);
command_args.push(derivation.builder.clone());
command_args.extend_from_slice(&derivation.arguments);
// produce output_paths, which is the absolute path of each output (sorted)
let mut output_paths: Vec<String> = derivation
.outputs
.values()
.map(|e| e.path_str()[1..].to_owned())
.collect();
// Sort the outputs. We can use sort_unstable, as these are unique strings.
output_paths.sort_unstable();
// Produce environment_vars and additional files.
// We use a BTreeMap while producing, and only realize the resulting Vec
// while populating BuildRequest, so we don't need to worry about ordering.
let mut environment_vars: BTreeMap<String, Bytes> = BTreeMap::new();
let mut additional_files: BTreeMap<String, Bytes> = BTreeMap::new();
// Start with some the ones that nix magically sets:
environment_vars.extend(
NIX_ENVIRONMENT_VARS
.iter()
.map(|(k, v)| (k.to_string(), Bytes::from_static(v.as_bytes()))),
);
// extend / overwrite with the keys set in the derivation environment itself.
// TODO: check if this order is correct, and environment vars set in the
// *Derivation actually* have priority.
environment_vars.extend(
derivation
.environment
.iter()
.map(|(k, v)| (k.clone(), Bytes::from(v.to_vec()))),
);
handle_pass_as_file(&mut environment_vars, &mut additional_files)?;
// TODO: handle __json (structured attrs, provide JSON file and source-able bash script)
// Produce constraints.
let constraints = Some(BuildConstraints {
system: derivation.system.clone(),
min_memory: 0,
available_ro_paths: vec![],
// in case this is a fixed-output derivation, allow network access.
network_access: derivation.outputs.len() == 1
&& derivation
.outputs
.get("out")
.expect("invalid derivation")
.is_fixed(),
provide_bin_sh: true,
});
let build_request = BuildRequest {
command_args,
outputs: output_paths,
// Turn this into a sorted-by-key Vec<EnvVar>.
environment_vars: environment_vars
.into_iter()
.map(|(key, value)| EnvVar { key, value })
.collect(),
inputs: inputs
.into_iter()
.map(|n| proto::Node { node: Some(n) })
.collect(),
inputs_dir: nix_compat::store_path::STORE_DIR[1..].into(),
constraints,
working_dir: "build".into(),
scratch_paths: vec!["build".into(), "nix/store".into()],
additional_files: additional_files
.into_iter()
.map(|(path, contents)| AdditionalFile { path, contents })
.collect(),
};
debug_assert!(
build_request.validate().is_ok(),
"invalid BuildRequest: {}",
build_request.validate().unwrap_err()
);
Ok(build_request)
}
/// handle passAsFile, if set.
/// For each env $x in that list, the original env is removed, and a $xPath
/// environment var added instead, referring to a path inside the build with
/// the contents from the original env var.
fn handle_pass_as_file(
environment_vars: &mut BTreeMap<String, Bytes>,
additional_files: &mut BTreeMap<String, Bytes>,
) -> std::io::Result<()> {
let pass_as_file = environment_vars.get("passAsFile").map(|v| {
// Convert pass_as_file to string.
// When it gets here, it contains a space-separated list of env var
// keys, which must be strings.
String::from_utf8(v.to_vec())
});
if let Some(pass_as_file) = pass_as_file {
let pass_as_file = pass_as_file.map_err(|_| {
std::io::Error::new(
std::io::ErrorKind::InvalidInput,
"passAsFile elements are no valid utf8 strings",
)
})?;
for x in pass_as_file.split(' ') {
match environment_vars.remove_entry(x) {
Some((k, contents)) => {
let (new_k, path) = calculate_pass_as_file_env(&k);
additional_files.insert(path[1..].to_string(), contents);
environment_vars.insert(new_k, Bytes::from(path));
}
None => {
return Err(std::io::Error::new(
std::io::ErrorKind::InvalidData,
"passAsFile refers to non-existent env key",
));
}
}
}
}
Ok(())
}
/// For a given key k in a derivation environment that's supposed to be passed as file,
/// calculate the ${k}Path key and filepath value that it's being replaced with
/// while preparing the build.
/// The filepath is `/build/.attrs-${nixbase32(sha256(key))`.
fn calculate_pass_as_file_env(k: &str) -> (String, String) {
(
format!("{}Path", k),
format!(
"/build/.attr-{}",
nixbase32::encode(&Sha256::new_with_prefix(k).finalize())
),
)
}
#[cfg(test)]
mod test {
use std::collections::BTreeSet;
use bytes::Bytes;
use nix_compat::derivation::Derivation;
use tvix_build::proto::{
build_request::{AdditionalFile, BuildConstraints, EnvVar},
BuildRequest,
};
use tvix_castore::{
fixtures::DUMMY_DIGEST,
proto::{self, node::Node, DirectoryNode},
};
use crate::tvix_build::NIX_ENVIRONMENT_VARS;
use super::derivation_to_build_request;
use lazy_static::lazy_static;
lazy_static! {
static ref INPUT_NODE_FOO: Node = Node::Directory(DirectoryNode {
name: Bytes::from("mp57d33657rf34lzvlbpfa1gjfv5gmpg-bar"),
digest: DUMMY_DIGEST.clone().into(),
size: 42,
});
}
#[test]
fn test_derivation_to_build_request() {
let aterm_bytes = include_bytes!("tests/ch49594n9avinrf8ip0aslidkc4lxkqv-foo.drv");
let derivation = Derivation::from_aterm_bytes(aterm_bytes).expect("must parse");
let build_request =
derivation_to_build_request(&derivation, BTreeSet::from([INPUT_NODE_FOO.clone()]))
.expect("must succeed");
let mut expected_environment_vars = vec![
EnvVar {
key: "bar".into(),
value: "/nix/store/mp57d33657rf34lzvlbpfa1gjfv5gmpg-bar".into(),
},
EnvVar {
key: "builder".into(),
value: ":".into(),
},
EnvVar {
key: "name".into(),
value: "foo".into(),
},
EnvVar {
key: "out".into(),
value: "/nix/store/fhaj6gmwns62s6ypkcldbaj2ybvkhx3p-foo".into(),
},
EnvVar {
key: "system".into(),
value: ":".into(),
},
];
expected_environment_vars.extend(NIX_ENVIRONMENT_VARS.iter().map(|(k, v)| EnvVar {
key: k.to_string(),
value: Bytes::from_static(v.as_bytes()),
}));
expected_environment_vars.sort_unstable_by_key(|e| e.key.to_owned());
assert_eq!(
BuildRequest {
command_args: vec![":".into()],
outputs: vec!["nix/store/fhaj6gmwns62s6ypkcldbaj2ybvkhx3p-foo".into()],
environment_vars: expected_environment_vars,
inputs: vec![proto::Node {
node: Some(INPUT_NODE_FOO.clone())
}],
inputs_dir: "nix/store".into(),
constraints: Some(BuildConstraints {
system: derivation.system.clone(),
min_memory: 0,
network_access: false,
available_ro_paths: vec![],
provide_bin_sh: true,
}),
additional_files: vec![],
working_dir: "build".into(),
scratch_paths: vec!["build".into(), "nix/store".into()],
},
build_request
);
}
#[test]
fn test_fod_to_build_request() {
let aterm_bytes = include_bytes!("tests/0hm2f1psjpcwg8fijsmr4wwxrx59s092-bar.drv");
let derivation = Derivation::from_aterm_bytes(aterm_bytes).expect("must parse");
let build_request =
derivation_to_build_request(&derivation, BTreeSet::from([])).expect("must succeed");
let mut expected_environment_vars = vec![
EnvVar {
key: "builder".into(),
value: ":".into(),
},
EnvVar {
key: "name".into(),
value: "bar".into(),
},
EnvVar {
key: "out".into(),
value: "/nix/store/4q0pg5zpfmznxscq3avycvf9xdvx50n3-bar".into(),
},
EnvVar {
key: "outputHash".into(),
value: "08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba".into(),
},
EnvVar {
key: "outputHashAlgo".into(),
value: "sha256".into(),
},
EnvVar {
key: "outputHashMode".into(),
value: "recursive".into(),
},
EnvVar {
key: "system".into(),
value: ":".into(),
},
];
expected_environment_vars.extend(NIX_ENVIRONMENT_VARS.iter().map(|(k, v)| EnvVar {
key: k.to_string(),
value: Bytes::from_static(v.as_bytes()),
}));
expected_environment_vars.sort_unstable_by_key(|e| e.key.to_owned());
assert_eq!(
BuildRequest {
command_args: vec![":".to_string()],
outputs: vec!["nix/store/4q0pg5zpfmznxscq3avycvf9xdvx50n3-bar".into()],
environment_vars: expected_environment_vars,
inputs: vec![],
inputs_dir: "nix/store".into(),
constraints: Some(BuildConstraints {
system: derivation.system.clone(),
min_memory: 0,
network_access: true,
available_ro_paths: vec![],
provide_bin_sh: true,
}),
additional_files: vec![],
working_dir: "build".into(),
scratch_paths: vec!["build".into(), "nix/store".into()],
},
build_request
);
}
#[test]
fn test_pass_as_file() {
// (builtins.derivation { "name" = "foo"; passAsFile = ["bar" "baz"]; bar = "baz"; baz = "bar"; system = ":"; builder = ":";}).drvPath
let aterm_bytes = r#"Derive([("out","/nix/store/pp17lwra2jkx8rha15qabg2q3wij72lj-foo","","")],[],[],":",":",[],[("bar","baz"),("baz","bar"),("builder",":"),("name","foo"),("out","/nix/store/pp17lwra2jkx8rha15qabg2q3wij72lj-foo"),("passAsFile","bar baz"),("system",":")])"#.as_bytes();
let derivation = Derivation::from_aterm_bytes(aterm_bytes).expect("must parse");
let build_request =
derivation_to_build_request(&derivation, BTreeSet::from([])).expect("must succeed");
let mut expected_environment_vars = vec![
// Note how bar and baz are not present in the env anymore,
// but replaced with barPath, bazPath respectively.
EnvVar {
key: "barPath".into(),
value: "/build/.attr-1fcgpy7vc4ammr7s17j2xq88scswkgz23dqzc04g8sx5vcp2pppw".into(),
},
EnvVar {
key: "bazPath".into(),
value: "/build/.attr-15l04iksj1280dvhbzdq9ai3wlf8ac2188m9qv0gn81k9nba19ds".into(),
},
EnvVar {
key: "builder".into(),
value: ":".into(),
},
EnvVar {
key: "name".into(),
value: "foo".into(),
},
EnvVar {
key: "out".into(),
value: "/nix/store/pp17lwra2jkx8rha15qabg2q3wij72lj-foo".into(),
},
// passAsFile stays around
EnvVar {
key: "passAsFile".into(),
value: "bar baz".into(),
},
EnvVar {
key: "system".into(),
value: ":".into(),
},
];
expected_environment_vars.extend(NIX_ENVIRONMENT_VARS.iter().map(|(k, v)| EnvVar {
key: k.to_string(),
value: Bytes::from_static(v.as_bytes()),
}));
expected_environment_vars.sort_unstable_by_key(|e| e.key.to_owned());
assert_eq!(
BuildRequest {
command_args: vec![":".to_string()],
outputs: vec!["nix/store/pp17lwra2jkx8rha15qabg2q3wij72lj-foo".into()],
environment_vars: expected_environment_vars,
inputs: vec![],
inputs_dir: "nix/store".into(),
constraints: Some(BuildConstraints {
system: derivation.system.clone(),
min_memory: 0,
network_access: false,
available_ro_paths: vec![],
provide_bin_sh: true,
}),
additional_files: vec![
// baz env
AdditionalFile {
path: "build/.attr-15l04iksj1280dvhbzdq9ai3wlf8ac2188m9qv0gn81k9nba19ds"
.into(),
contents: "bar".into()
},
// bar env
AdditionalFile {
path: "build/.attr-1fcgpy7vc4ammr7s17j2xq88scswkgz23dqzc04g8sx5vcp2pppw"
.into(),
contents: "baz".into(),
},
],
working_dir: "build".into(),
scratch_paths: vec!["build".into(), "nix/store".into()],
},
build_request
);
}
}
