diff --git a/doc/manual/command-ref/conf-file.xml b/doc/manual/command-ref/conf-file.xml
index 96f8a4b60..b1b604100 100644
--- a/doc/manual/command-ref/conf-file.xml
+++ b/doc/manual/command-ref/conf-file.xml
@@ -644,6 +644,16 @@ password my-password
+ allow-import-from-derivation
+
+ By default, nix allows you to import from a derivation,
+ allowing building at evaluation time. With this option set to false, nix will throw an error
+ when evaluating an expression that uses this feature, allowing users to ensure their evaluation
+ will not require any builds to take place.
+
+
+
+
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 5a570cefb..93097f3d1 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -59,6 +59,8 @@ void EvalState::realiseContext(const PathSet & context)
drvs.insert(decoded.first + "!" + decoded.second);
}
if (!drvs.empty()) {
+ if (!settings.enableImportFromDerivation)
+ throw EvalError(format("attempted to realize ‘%1%’ during evaluation but 'allow-import-from-derivation' is false") % *(drvs.begin()));
/* For performance, prefetch all substitute info. */
PathSet willBuild, willSubstitute, unknown;
unsigned long long downloadSize, narSize;
diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index fcd634729..df537a512 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -70,6 +70,7 @@ Settings::Settings()
enableImportNative = false;
netrcFile = fmt("%s/%s", nixConfDir, "netrc");
caFile = getEnv("NIX_SSL_CERT_FILE", getEnv("SSL_CERT_FILE", "/etc/ssl/certs/ca-certificates.crt"));
+ enableImportFromDerivation = true;
}
@@ -185,6 +186,7 @@ void Settings::update()
_get(keepGoing, "keep-going");
_get(keepFailed, "keep-failed");
_get(netrcFile, "netrc-file");
+ _get(enableImportFromDerivation, "allow-import-from-derivation");
}
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 1e6b7c083..7a9a9f6c0 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -198,6 +198,9 @@ struct Settings {
/* Path to the SSL CA file used */
Path caFile;
+ /* Whether we allow import-from-derivation */
+ bool enableImportFromDerivation;
+
private:
SettingsMap settings, overrides;