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Source complete env in nix-shell with __structuredAttrs = true;

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This is needed to push the adoption of structured attrs[1] forward. It's
now checked if a `__json` exists in the environment-map of the derivation
to be openend in a `nix-shell`.

Derivations with structured attributes enabled also make use of a file
named `.attrs.json` containing every environment variable represented as
JSON which is useful for e.g. `exportReferencesGraph`[2]. To
provide an environment similar to the build sandbox, `nix-shell` now
adds a `.attrs.json` to `cwd` (which is mostly equal to the one in the
build sandbox) and removes it using an exit hook when closing the shell.

To avoid leaking internals of the build-process to the `nix-shell`, the
entire logic to generate JSON and shell code for structured attrs was
moved into the `ParsedDerivation` class.

[1] https://nixos.mayflower.consulting/blog/2020/01/20/structured-attrs/
[2] https://nixos.org/manual/nix/unstable/expressions/advanced-attributes.html#advanced-attributes
This commit is contained in:
Maximilian Bosch 2021-05-02 17:24:14 +02:00
parent 4b23bf797a
commit 3b5429aec1
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GPG key ID: 091DBF4D1FC46B8E
9 changed files with 227 additions and 145 deletions
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45
src/nix-build/nix-build.cc
View file

@ -1,10 +1,15 @@
#include <cstring>
#include <fstream>
#include <iostream>
#include <filesystem>
#include <regex>
#include <sstream>
#include <vector>
#include <map>
#include <nlohmann/json.hpp>
#include "parsed-derivations.hh"
#include "store-api.hh"
#include "local-fs-store.hh"
#include "globals.hh"
@ -422,12 +427,41 @@ static void main_nix_build(int argc, char * * argv)
} else
env[var.first] = var.second;
std::string structuredAttrsRC;
std::string exitCmd;
if (env.count("__json")) {
StorePathSet inputs;
for (auto & [depDrvPath, wantedDepOutputs] : drv.inputDrvs) {
auto outputs = store->queryPartialDerivationOutputMap(depDrvPath);
for (auto & i : wantedDepOutputs) {
auto o = outputs.at(i);
store->computeFSClosure(*o, inputs);
}
}
ParsedDerivation parsedDrv(
StorePath(store->parseStorePath(drvInfo.queryDrvPath())),
drv
);
if (auto structAttrs = parsedDrv.generateStructuredAttrs(std::nullopt, *store, inputs)) {
auto val = structAttrs.value();
structuredAttrsRC = val.first;
auto attrsJSON = std::filesystem::current_path().string() + "/.attrs.json";
writeFile(attrsJSON, val.second.dump());
exitCmd = "\n_rm_attrs_json() { rm -f " + attrsJSON + "; }"
+ "\nexitHooks+=(_rm_attrs_json)"
+ "\nfailureHooks+=(_rm_attrs_json)\n";
}
}
/* Run a shell using the derivation's environment. For
convenience, source $stdenv/setup to setup additional
environment variables and shell functions. Also don't
lose the current $PATH directories. */
auto rcfile = (Path) tmpDir + "/rc";
writeFile(rcfile, fmt(
std::string rc = fmt(
R"(_nix_shell_clean_tmpdir() { rm -rf %1%; }; )"s +
(keepTmp ?
"trap _nix_shell_clean_tmpdir EXIT; "
@ -436,8 +470,9 @@ static void main_nix_build(int argc, char * * argv)
"_nix_shell_clean_tmpdir; ") +
(pure ? "" : "[ -n \"$PS1\" ] && [ -e ~/.bashrc ] && source ~/.bashrc;") +
"%2%"
"dontAddDisableDepTrack=1; "
"[ -e $stdenv/setup ] && source $stdenv/setup; "
"dontAddDisableDepTrack=1;\n"
+ structuredAttrsRC + exitCmd +
"\n[ -e $stdenv/setup ] && source $stdenv/setup; "
"%3%"
"PATH=%4%:\"$PATH\"; "
"SHELL=%5%; "
@ -455,7 +490,9 @@ static void main_nix_build(int argc, char * * argv)
shellEscape(dirOf(*shell)),
shellEscape(*shell),
(getenv("TZ") ? (string("export TZ=") + shellEscape(getenv("TZ")) + "; ") : ""),
envCommand));
envCommand);
vomit("Sourcing nix-shell with file %s and contents:\n%s", rcfile, rc);
writeFile(rcfile, rc);
Strings envStrs;
for (auto & i : env)