feat(back): #894 generate provenance

- Generate some basic fields of provenance that
  are easy to collect from the environment

src/cli/main/__main__.py

@@ -1,3 +1,4 @@
+# pylint: disable=too-many-lines
 from contextlib import (
     suppress,
 )
@@ -7,9 +8,11 @@
 import io
 import json
 import operator
+import os
 from os import (
     environ,
     getcwd,
+    getlogin,
     makedirs,
     remove,
 )
@@ -33,6 +36,9 @@
 import rich.text
 import shlex
 import shutil
+from socket import (
+    gethostname,
+)
 import subprocess  # nosec
 import sys
 import tempfile
@@ -250,6 +256,15 @@ def _clone_src_git_init(head: str) -> None:
         raise SystemExit(out)
 
 
+def _clone_src_git_rev_parse(head: str, rev: str) -> str:
+    cmd = ["git", "-C", head, "rev-parse", rev]
+    out, stdout, _ = _run_outputs(cmd, stderr=None)
+    if out != 0:
+        raise SystemExit(out)
+
+    return next(iter(stdout.decode().splitlines()), "HEAD")
+
+
 def _clone_src_git_fetch(head: str, remote: str, rev: str) -> None:
     depth = _if(GIT_DEPTH >= 1, f"--depth={GIT_DEPTH}")
     cmd = ["git", "-C", head, "fetch", *depth, remote, f"{rev}:{rev}"]
@@ -379,6 +394,45 @@ def _nix_build(
     ]
 
 
+def _nix_hashes(*paths: str) -> List[str]:
+    cmd = [
+        f"{__NIX_STABLE__}/bin/nix-store",
+        "--query",
+        "--hash",
+        *paths,
+    ]
+    out, stdout, _ = _run_outputs(cmd, stderr=None)
+    if out != 0:
+        raise SystemExit(out)
+
+    return stdout.decode().splitlines()
+
+
+def _nix_build_requisites(path: str) -> List[Tuple[str, str]]:
+    """Answer the question: what do I need to build `out`."""
+    cmd = [f"{__NIX_STABLE__}/bin/nix-store", "--query", "--deriver", path]
+    out, stdout, _ = _run_outputs(cmd, stderr=None)
+    if out != 0:
+        raise SystemExit(out)
+
+    cmd = [
+        f"{__NIX_STABLE__}/bin/nix-store",
+        "--query",
+        "--requisites",
+        "--include-outputs",
+        *stdout.decode().splitlines(),
+    ]
+    out, stdout, _ = _run_outputs(cmd, stderr=None)
+    if out != 0:
+        raise SystemExit(out)
+
+    requisites: List[str] = stdout.decode().splitlines()
+
+    hashes: List[str] = _nix_hashes(*requisites)
+
+    return list(zip(requisites, hashes))
+
+
 def _get_head(src: str) -> str:
     # Checkout repository HEAD into a temporary directory
     # This is nice for reproducibility and security,
@@ -775,9 +829,11 @@ def cli(args: List[str]) -> None:
     args, attr = _cli_get_args_and_attr(args, config.attrs, src)
 
     out: str = join(MAKES_DIR, f"out{attr.replace('/', '-')}")
+    provenance: str = join(MAKES_DIR, f"provenance{attr.replace('/', '-')}")
     code = _cli_build(attr, config, head, out, src)
 
     if code == 0:
+        write_provenance(args, head, out, provenance, src)
         cache_push(config.cache, out)
         execute_action(args[3:], head, out)
 
@@ -862,6 +918,76 @@ def cache_push(cache: List[Dict[str, str]], out: str) -> None:
             return
 
 
+def _get_sys_id() -> str:
+    with suppress(AttributeError):
+        uname = os.uname()
+        return f"{uname.nodename}-{uname.sysname}-{uname.machine}"
+
+    with suppress(OSError):
+        return gethostname()
+
+    return "unknown"
+
+
+def _get_usr() -> str:
+    with suppress(OSError):
+        return getlogin()
+
+    return "unknown"
+
+
+def write_provenance(
+    args: List[str],
+    head: str,
+    out: str,
+    provenance: str,
+    src: str,
+) -> None:
+    attestation: Dict[str, Any] = {}
+    attestation["_type"] = "https://in-toto.io/Statement/v0.1"
+    attestation["predicateType"] = "https://slsa.dev/provenance/v0.2"
+
+    attestation["predicate"] = {}
+    attestation["predicate"]["builder"] = {}
+    attestation["predicate"]["builder"]["id"] = f"{_get_usr()}@{_get_sys_id()}"
+    attestation["predicate"]["buildType"] = (
+        f"https://fluidattacks.com/Attestations/Makes@{VERSION}",
+    )
+    attestation["predicate"]["invocation"] = {}
+    attestation["predicate"]["invocation"]["configSource"] = {
+        "uri": f"git+https://{src}",
+        "digest": {"sha1": _clone_src_git_rev_parse(head, "HEAD")},
+        "entrypoint": args[0],
+    }
+    attestation["predicate"]["invocation"]["parameters"] = args[1:]
+    attestation["predicate"]["invocation"]["environment"] = {
+        key: "" for key in environ
+    }
+    attestation["predicate"]["metadata"] = {}
+    attestation["predicate"]["metadata"]["completeness"] = {}
+    attestation["predicate"]["metadata"]["completeness"]["environment"] = True
+    attestation["predicate"]["metadata"]["completeness"]["materials"] = True
+    attestation["predicate"]["metadata"]["completeness"]["parameters"] = True
+    attestation["predicate"]["metadata"]["reproducible"] = True
+    attestation["predicate"]["materials"] = [
+        {
+            "uri": requisite,
+            "hash": dict([hash_.split(":")]),  # type: ignore
+        }
+        for requisite, hash_ in _nix_build_requisites(out)
+    ]
+
+    attestation["subject"] = [
+        {
+            "uri": out,
+            "hash": dict([_nix_hashes(out)[0].split(":")]),  # type: ignore
+        }
+    ]
+
+    with open(provenance, encoding="utf-8", mode="w+") as attestation_file:
+        json.dump(attestation, attestation_file, indent=2, sort_keys=True)
+
+
 def main() -> None:
     try:
         cli(sys.argv)