snix_build/oci/
bundle.rs

1//! Module to create an OCI runtime bundle for a given [BuildRequest].
2use std::{
3    fs,
4    path::{Path, PathBuf},
5};
6
7use super::scratch_name;
8use crate::buildservice::BuildRequest;
9use anyhow::{Context, bail};
10use tracing::{debug, instrument};
11
12/// Produce an OCI bundle in a given path.
13/// Check [super::spec::make_spec] for a description about the paths produced.
14#[instrument(err)]
15pub(crate) fn make_bundle<'a>(
16    request: &BuildRequest,
17    runtime_spec: &oci_spec::runtime::Spec,
18    path: &Path,
19) -> anyhow::Result<()> {
20    fs::create_dir_all(path).context("failed to create bundle path")?;
21
22    let spec_json = serde_json::to_string(runtime_spec).context("failed to render spec to json")?;
23    fs::write(path.join("config.json"), spec_json).context("failed to write config.json")?;
24
25    fs::create_dir_all(path.join("inputs")).context("failed to create inputs dir")?;
26
27    let root_path = path.join("root");
28
29    fs::create_dir_all(&root_path).context("failed to create root path dir")?;
30    fs::create_dir_all(root_path.join("etc")).context("failed to create root/etc dir")?;
31
32    // TODO: populate /etc/{group,passwd}. It's a mess?
33
34    let scratch_root = path.join("scratch");
35    fs::create_dir_all(&scratch_root).context("failed to create scratch/ dir")?;
36
37    // for each scratch path, calculate its name inside scratch, and ensure the
38    // directory exists.
39    for p in request.scratch_paths.iter() {
40        let scratch_path = scratch_root.join(scratch_name(p));
41        debug!(scratch_path=?scratch_path, path=?p, "about to create scratch dir");
42        fs::create_dir_all(scratch_path).context("Unable to create scratch dir")?;
43    }
44
45    Ok(())
46}
47
48/// Determine the path of all outputs specified in a [BuildRequest]
49/// as seen from the host, for post-build ingestion.
50/// This lookup needs to take scratch paths into consideration, as the build
51/// root is not writable on its own.
52/// If a path can't be determined, an error is returned.
53pub(crate) fn get_host_output_paths(
54    request: &BuildRequest,
55    bundle_path: &Path,
56) -> anyhow::Result<Vec<PathBuf>> {
57    let scratch_root = bundle_path.join("scratch");
58
59    let mut host_output_paths: Vec<PathBuf> = Vec::with_capacity(request.outputs.len());
60
61    for output_path in request.outputs.iter() {
62        // calculate the location of the path.
63        if let Some((mp, relpath)) = find_path_in_scratchs(output_path, &request.scratch_paths) {
64            host_output_paths.push(scratch_root.join(scratch_name(mp)).join(relpath));
65        } else {
66            bail!("unable to find path {output_path:?}");
67        }
68    }
69
70    Ok(host_output_paths)
71}
72
73/// For a given list of mountpoints (sorted) and a search_path, find the
74/// specific mountpoint parenting that search_path and return it, as well as the
75/// relative path from there to the search_path.
76/// mountpoints must be sorted, so we can iterate over the list from the back
77/// and match on the prefix.
78fn find_path_in_scratchs<'a, 'b, I>(
79    search_path: &'a Path,
80    mountpoints: I,
81) -> Option<(&'b Path, &'a Path)>
82where
83    I: IntoIterator<Item = &'b PathBuf>,
84    I::IntoIter: DoubleEndedIterator,
85{
86    mountpoints
87        .into_iter()
88        .rev()
89        .find_map(|mp| Some((mp.as_path(), search_path.strip_prefix(mp).ok()?)))
90}
91
92#[cfg(test)]
93mod tests {
94    use std::path::{Path, PathBuf};
95
96    use rstest::rstest;
97
98    use crate::{buildservice::BuildRequest, oci::scratch_name};
99
100    use super::{find_path_in_scratchs, get_host_output_paths};
101
102    #[rstest]
103    #[case::simple("nix/store/aaaa", &["nix/store".into()], Some(("nix/store", "aaaa")))]
104    #[case::prefix_no_sep("nix/store/aaaa", &["nix/sto".into()], None)]
105    #[case::not_found("nix/store/aaaa", &["build".into()], None)]
106    fn test_test_find_path_in_scratchs(
107        #[case] search_path: &str,
108        #[case] mountpoints: &[String],
109        #[case] expected: Option<(&str, &str)>,
110    ) {
111        let expected = expected.map(|e| (Path::new(e.0), Path::new(e.1)));
112        assert_eq!(
113            find_path_in_scratchs(
114                Path::new(search_path),
115                mountpoints
116                    .iter()
117                    .map(PathBuf::from)
118                    .collect::<Vec<_>>()
119                    .as_slice()
120            ),
121            expected
122        );
123    }
124
125    #[test]
126    fn test_get_host_output_paths_simple() {
127        let request = BuildRequest {
128            outputs: vec!["nix/store/fhaj6gmwns62s6ypkcldbaj2ybvkhx3p-foo".into()],
129            scratch_paths: vec!["build".into(), "nix/store".into()],
130            ..Default::default()
131        };
132
133        let paths =
134            get_host_output_paths(&request, Path::new("bundle-root")).expect("must succeed");
135
136        let mut expected_path = PathBuf::new();
137        expected_path.push("bundle-root");
138        expected_path.push("scratch");
139        expected_path.push(scratch_name(Path::new("nix/store")));
140        expected_path.push("fhaj6gmwns62s6ypkcldbaj2ybvkhx3p-foo");
141
142        assert_eq!(vec![expected_path], paths)
143    }
144}
snix_build/oci/bundle.rs

snix_build/oci/
bundle.rs
