Merge pull request #42371 from Mic92/nix-breakpoints

breakpointHook: add for debugging failing builds

doc/stdenv.xml

@@ -2445,6 +2445,25 @@ addEnvHooks "$hostOffset" myBashFunction
       </para>
      </listitem>
     </varlistentry>
+    <varlistentry>
+     <term>
+      breakpointHook
+     </term>
+     <listitem>
+      <para>
+       This hook will make a build pause instead of stopping
+       when a failure happen. It prevents nix to cleanup the build
+       environment immediatly and allows the user to attach
+       to a build environemnt using the <varname>cntr</varname> command.
+       On build error it will print the instruction that are neccessary for cntr.
+       Note that <varname>cntr</varname> is not installed by default and
+       needs to be installed seperatly. <varname>cntr</varname> also needs to be executed
+       on the machine that is doing the build, which might be not the case
+       when remote builders are enabled. <varname>cntr</varname> is only supported
+       on linux based platforms.
+      </para>
+     </listitem>
+    </varlistentry>
    </variablelist>
   </para>
  </section>

pkgs/applications/virtualization/cntr/default.nix

@@ -0,0 +1,24 @@
+{ stdenv, rustPlatform, fetchFromGitHub }:
+
+rustPlatform.buildRustPackage rec {
+  name = "cntr-${version}";
+  version = "1.2.0";
+
+  src = fetchFromGitHub {
+    owner = "Mic92";
+    repo = "cntr";
+    rev = version;
+    sha256 = "0lmbsnjia44h4rskqkv9yc7xb6f3qjgbg8kcr9zqnr7ivr5fjcxg";
+  };
+
+  cargoSha256 = "0gainr5gfy0bbhr6078zvgx0kzp53slxjp37d3da091ikgzgfn51";
+
+  meta = with stdenv.lib; {
+    description = "A container debugging tool based on FUSE";
+    homepage = https://github.com/Mic92/cntr;
+    license = licenses.mit;
+    # aarch64 support will be fixed soon
+    platforms = [ "x86_64-linux" ];
+    maintainers = [ maintainers.mic92 ];
+  };
+}

pkgs/build-support/setup-hooks/breakpoint-hook.sh

@@ -0,0 +1,9 @@
+breakpointHook() {
+    local red='\033[0;31m'
+    local no_color='\033[0m'
+
+    echo -e "${red}build failed in ${curPhase} with exit code ${exitCode}${no_color}"
+    printf "To attach install cntr and run the following command as root:\n\n"
+    sh -c "echo '   cntr attach -t command cntr-${out}'; while true; do sleep 99999999; done"
+}
+failureHooks+=(breakpointHook)

pkgs/top-level/all-packages.nix

@@ -977,6 +977,9 @@ with pkgs;
 
   bruteforce-luks = callPackage ../tools/security/bruteforce-luks { };
 
+  breakpointHook = assert stdenv.isLinux;
+    makeSetupHook { } ../build-support/setup-hooks/breakpoint-hook.sh;
+
   bsod = callPackage ../misc/emulators/bsod { };
 
   btrfs-progs = callPackage ../tools/filesystems/btrfs-progs { };
@@ -16010,6 +16013,8 @@ with pkgs;
   cni = callPackage ../applications/networking/cluster/cni {};
   cni-plugins = callPackage ../applications/networking/cluster/cni/plugins.nix {};
 
+  cntr = callPackage ../applications/virtualization/cntr { };
+
   communi = libsForQt5.callPackage ../applications/networking/irc/communi { };
 
   confclerk = callPackage ../applications/misc/confclerk { };