ENT-14460: Added build flake to buidlscripts

.gitignore

@@ -3,3 +3,4 @@ revision
 *.html
 ci/cache
 ci/packages
+contrib/nix/flake.lock

contrib/nix/README.md

@@ -0,0 +1,78 @@
+
+# Building CFEngine with nix
+
+## Common workflow
+
+You add a change in one of your repo. This workflow assumes you commit your changes first — `nix flake update` needs a stable commit to pin to (an uncommitted/dirty tree is handled differently; see the note at the end).
+
+
+```
+victor-moene@victomoe:~/northern.tech/cfengine/core (cfengine-flake)$ touch a
+victor-moene@victomoe:~/northern.tech/cfengine/core (cfengine-flake)$ git add a 
+victor-moene@victomoe:~/northern.tech/cfengine/core (cfengine-flake)$ git commit -m "a"
+[cfengine-flake 150282eb4] a
+ 1 file changed, 0 insertions(+), 0 deletions(-)
+ create mode 100644 a
+victor-moene@victomoe:~/northern.tech/cfengine/core (cfengine-flake)$ git status
+On branch cfengine-flake
+Your branch is ahead of 'origin/cfengine-flake' by 1 commit.
+  (use "git push" to publish your local commits)
+
+nothing to commit, working tree clean
+```
+
+Then you update buildscripts' flake.lock
+
+```
+victor-moene@victomoe:~/northern.tech/cfengine/buildscripts/contrib/nix (cfengine-buildscripts-flake)$ nix flake update
+warning: Git tree '/home/victor-moene/northern.tech/cfengine/buildscripts' is dirty
+warning: updating lock file "/home/victor-moene/northern.tech/cfengine/buildscripts/contrib/nix/flake.lock":
+• Updated input 'core':
+    'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=87d67cce8b4367d21139282256d23f7f407aca49&submodules=1' (2026-09-07)
+  → 'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=150282eb48c808a745abcdfee69cc0d409313a14&submodules=1' (2026-09-07)
+• Updated input 'enterprise/core':
+    'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=87d67cce8b4367d21139282256d23f7f407aca49&submodules=1' (2026-09-07)
+  → 'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=150282eb48c808a745abcdfee69cc0d409313a14&submodules=1' (2026-09-07)
+• Updated input 'mission-portal/nova/core':
+    'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=87d67cce8b4367d21139282256d23f7f407aca49&submodules=1' (2026-09-07)
+  → 'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=150282eb48c808a745abcdfee69cc0d409313a14&submodules=1' (2026-09-07)
+• Updated input 'mission-portal/nova/enterprise/core':
+    'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=87d67cce8b4367d21139282256d23f7f407aca49&submodules=1' (2026-09-07)
+  → 'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=150282eb48c808a745abcdfee69cc0d409313a14&submodules=1' (2026-09-07)
+• Updated input 'nova/core':
+    'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=87d67cce8b4367d21139282256d23f7f407aca49&submodules=1' (2026-09-07)
+  → 'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=150282eb48c808a745abcdfee69cc0d409313a14&submodules=1' (2026-09-07)
+• Updated input 'nova/enterprise/core':
+    'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=87d67cce8b4367d21139282256d23f7f407aca49&submodules=1' (2026-09-07)
+  → 'git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix&ref=refs/heads/cfengine-flake&rev=150282eb48c808a745abcdfee69cc0d409313a14&submodules=1' (2026-09-07)
+```
+
+In short, the flake.lock is a file pinning all the inputs of the final derivation.
+
+Now you can build with the newest commit:
+
+```
+victor-moene@victomoe:~/northern.tech/cfengine/buildscripts/contrib/nix (cfengine-buildscripts-flake)$ nix build .#community-client -o myoutput
+```
+
+You can choose to build `community-client`, `enterprise-client` or `enterprise-hub`. These are listed in `buildscripts/contrib/nix/flake.nix`
+
+Where myoutput is a symlink with the compiled binaries. For exemple, from a previous build, I got:
+
+```
+victor-moene@victomoe:~/northern.tech/cfengine/buildscripts/contrib/nix (cfengine-buildscripts-flake)$ ls myoutput
+bin  cgi-bin  conf  error  etc  htdocs  icons  lib  logs  masterfiles  master_software_updates  modules  php  sbin  share  var
+```
+
+CFEngine expects some level of permissions on its source files, so you might have to copy the output somewhere else.
+
+## Sharing builds
+
+To share fully reproducible builds, simply share the `flake.lock` file, and run nix build. This assumes you have the same commits in the repos.
+
+## Garbage collection
+
+Nix stores every derivation as a unique package in the Nix store, so disk usage can grow quickly. Run `nix-collect-garbage` (or `nix-collect-garbage -d` to also remove old generations) from time to time to reclaim space.
+
+Note: any `-o` result symlink (e.g. `myoutput`) acts as a garbage-collection root — as long as it exists, Nix won't clean up the store paths it points to. Remove old output symlinks you no longer need before running garbage collection, or point `-o` at `/tmp` so they get cleaned up automatically.
+

contrib/nix/community-client.nix

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+{ symlinkJoin, core, masterfiles }:
+
+symlinkJoin {
+  name = "cfengine-community-client";
+  paths = [ core masterfiles ];
+}

contrib/nix/enterprise-client.nix

@@ -0,0 +1,9 @@
+{ symlinkJoin, core, enterprise }:
+
+# Deliberately no masterfiles here: an enterprise agent gets its policy
+# from the hub it's bootstrapped to, unlike the standalone community
+# agent, which ships default policy to bootstrap itself.
+symlinkJoin {
+  name = "cfengine-enterprise-client";
+  paths = [ core enterprise ];
+}

contrib/nix/enterprise-hub.nix

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+{ symlinkJoin, core, enterprise, nova, masterfiles, missionPortal, apacheHttpd, php }:
+
+# apacheHttpd/php are included so they're on PATH/in the closure for
+# whoever deploys this (a NixOS module, a container, ...) to actually run
+# the hub's web UI against -- this derivation doesn't configure or start
+# Apache itself, same as it doesn't start cf-serverd/cf-hub.
+symlinkJoin {
+  name = "cfengine-enterprise-hub";
+  paths = [ core enterprise nova masterfiles missionPortal apacheHttpd php ];
+}

contrib/nix/flake.nix

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+{
+  description = "CFEngine meta-flake: community-client, enterprise-client, enterprise-hub";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    # Absolute paths required -- see the comment in
+    # enterprise/contrib/nix/flake.nix for why relative "../.." doesn't
+    # work here.
+    core.url = "git+file:///home/victor-moene/northern.tech/cfengine/core?dir=contrib/nix";
+    enterprise.url = "git+file:///home/victor-moene/northern.tech/cfengine/enterprise?dir=contrib/nix";
+    nova.url = "git+file:///home/victor-moene/northern.tech/cfengine/nova?dir=contrib/nix";
+    masterfiles.url = "git+file:///home/victor-moene/northern.tech/cfengine/masterfiles?dir=contrib/nix";
+    mission-portal.url = "git+file:///home/victor-moene/northern.tech/cfengine/mission-portal?dir=contrib/nix";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, core, enterprise, nova, masterfiles, mission-portal }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+
+        coreOut = core.packages.${system}.default;
+        enterpriseOut = enterprise.packages.${system}.default;
+        novaOut = nova.packages.${system}.default;
+        masterfilesOut = masterfiles.packages.${system}.default;
+        missionPortalOut = mission-portal.packages.${system}.default;
+      in
+      {
+        packages = {
+          community-client = pkgs.callPackage ./community-client.nix {
+            core = coreOut;
+            masterfiles = masterfilesOut;
+          };
+          enterprise-client = pkgs.callPackage ./enterprise-client.nix {
+            core = coreOut;
+            enterprise = enterpriseOut;
+          };
+          enterprise-hub = pkgs.callPackage ./enterprise-hub.nix {
+            core = coreOut;
+            enterprise = enterpriseOut;
+            nova = novaOut;
+            masterfiles = masterfilesOut;
+            missionPortal = missionPortalOut;
+          };
+        };
+      }
+    );
+}