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1= Fleet23++++4<p align="center"><a href="https://github.com/CertainLach/fleet"><img alt="fleet temporary logo generated with midjourney" src="./docs/tmplogo.png" width="200px"></img></a></p>5++++67An NixOS cluster deployment tool.89== Advantages over existing configuration systems (NixOps/Morph)1011- Modules can configure multiple hosts at once (I.e for wireguard/kubernetes installation)12- Secrets can be securely stored in Git (No one except target hosts can decrypt them), automatically regenerated, reencrypted, etc.13- Automatic rollback on deployment failure, which will work, as long as system is passing initrd stage (So still be carefull with root filesystem mount)1415== Flake example1617[source,nix]18----19{20  description = "My cluster configuration";21  inputs = {22    nixpkgs.url = "github:nixos/nixpkgs";23    fleet = {24      url = "github:CertainLach/fleet";25      inputs.nixpkgs.follows = "nixpkgs";26    };27    lanzaboote = {28      url = "github:nix-community/lanzaboote/v0.3.0";29      inputs.nixpkgs.follows = "nixpkgs";30    };31  };32  outputs = {33    nixpkgs,34    fleet,35    lanzaboote,36    ...37  }: {38    # TODO: This section of documentation needs to use flake-utils.39    formatter.x86_64-linux = let40      pkgs = import nixpkgs {system = "x86_64-linux";};41    in42      pkgs.alejandra;4344    devShell.x86_64-linux = let45      pkgs = import nixpkgs {46        system = "x86_64-linux";47      };48    in49      pkgs.mkShell {50        buildInputs = with pkgs; [51          fleet.packages.x86_64-linux.fleet52        ];53      };5455    # Single flake may contain multiple fleet configurations, default one is called... `default`56    fleetConfigurations.default = fleet.lib.fleetConfiguration {57      # nixpkgs used to build the systems58      inherit nixpkgs;59      # fleet wants to pass some data, like secrets, to do that - fleet writes all the encrypted secrets to fleet.nix60      # treat the contents of this file as implementation detail61      data = import ./fleet.nix;62      63      # nixosModules section of fleet config declares modules, which are used for all configured nixos hosts.64      nixosModules = [65        lanzaboote.nixosModules.lanzaboote66        {67          # Make `nix shell nixpkgs#thing` use the same nixpkgs, as used to build the system.68          nix.registry.nixpkgs = {69            from = { id = "nixpkgs"; type = "indirect"; };70            flake = nixpkgs;71            exact = false;72          };73        }74      ];7576      # Those modules are used to configure all the machines in cluster at the same time, good example of global modules77      # Is I.e wiring up the mesh VPN, or deploying kubernetes, or other things.78      #79      # Modules use the same semantics as standard nixos module system, they are just configuring all the hosts at once.80      fleetModules = [81        ./wireguard82        # Multi-instancible modules example83        (import ./kubernetes {hosts = ["a" "b"];})84        (import ./kubernetes {hosts = ["c" "d"];})85      ];8687      # Hosts attribute (may also be defined/extended using modules attribute) configures hosts...88      hosts.controlplane-1 = {89        # Every host has some system, for which the system configuration needs to be built90        system = "x86_64-linux";91        # And nixos modules92        nixosModules = [93          ./controlplane-1/hardware-configuration.nix94          ./controlplane-1/configuration.nix95          # Configuration may also be specified inline, as in any nixos config.96          {97            services.ray = {98              gpus = 4;99              cpus = 128;100            };101          }102        ];103      };104    };105  };106}107----108109== Secret generator example110111TODO:: This section should into some kind of fleet documentation... But as there is none, it is just left here as-is.112113=== Quickly run securely setup gitlab114115[source,nix]116----117{config, ...}: {118  secrets = let ownership = { owner = "gitlab"; group = "gitlab"; }; in {119    gitlab-initial-root = {120      generator = {mkPassword}: mkPassword {};121    } // ownership;122    gitlab-secret = {123      generator = {mkPassword}: mkPassword {};124    } // ownership;125    gitlab-otp = {126      generator = {mkPassword}: mkPassword {};127    } // ownership;128    gitlab-db = {129      generator = {mkPassword}: mkPassword {};130    } // ownership;131    gitlab-jws = {132      generator = {mkRsa}: mkRsa {};133    } // ownership;134  };135  services.gitlab = let secrets = config.secrets; in {136    enable = true;137    initialRootPasswordFile = secrets.gitlab-initial-root.secretPath;138    secrets = {139      secretFile = secrets.gitlab-secret.secretPath;140      otpFile = secrets.gitlab-otp.secretPath;141      dbFile = secrets.gitlab-db.secretPath;142      jwsFile = secrets.gitlab-jws.secretPath;143    };144  };145}146----147148=== Securely initialize kubernetes secrets149150In my homelab and clusters, I almost always have some sort of HSM, and to issue new kubernetes certs I directly connect to it.151This setup should probably split into multiple steps, where I allow target machine to generate CSR, then copy it to the HSM machine, and then sign it there... But this is just the plan.152I want to build ansible-like script execution in fleet for this kind of tasks.153154[source,nix]155----156{...}: {157  # First I define required secret generators:158  nixpkgs.overlays = [159    (final: prev: let160      lib = final.lib;161    in {162      readKubernetesCa = {impureOn}:163        final.mkImpureSecretGenerator ''164          cd ~/ca165166          cert=kubernetes-intermediateCA.crt167168          expires_at=$(openssl x509 -in $cert -noout -enddate | cut -d= -f2 | xargs -I{} date -u -d {} +"%Y-%m-%dT%H:%M:%S.%NZ")169          echo -n $expires_at > $out/expires_at170171          cat $cert > $out/public172        ''173        impureOn;174      mkKubernetesCert = {175        subj,176        sans ? [],177        impureOn,178      }:179        final.mkImpureSecretGenerator ''180          cd ~/ca181182          params=$(sudo mktemp)183          csr=$(sudo mktemp)184          cert=$(sudo mktemp)185          sudo openssl ecparam -genkey -name secp384r1 -out $params186          sudo openssl req -new -key $params \187            -subj "${lib.strings.concatStringsSep "" (lib.attrsets.mapAttrsToList (k: v: "/${k}=${v}") subj)}" \188            ${lib.optionalString (sans != []) "-addext \"subjectAltName = ${lib.strings.concatStringsSep "," sans}\""} \189            -out $csr190          sudo hsms x509 -req -days 365 -in $csr -CA kubernetes-intermediateCA.crt -CAkey "pkcs11:object=[CENSORED] Kubernetes Intermediate CA;type=private" -CAcreateserial -copy_extensions copy -out $cert191192          expires_at=$(sudo openssl x509 -in $cert -noout -enddate | cut -d= -f2 | xargs -I{} date -u -d {} +"%Y-%m-%dT%H:%M:%S.%NZ")193          echo -n $expires_at > $out/expires_at194195          sudo cat $params | encrypt > $out/secret196          sudo cat $cert > $out/public197        ''198        impureOn;199    })200  ];201  # Those secret generators are impure, thus they are run in system environment.202  # Probably there needs to be a dedicated user for that kind of tasks, but this is my current setup, don't judge.203  # I write a couple of scripts for executing openssl with HSM.204  environment.systemPackages = [205    pkgs.openssl.bin206    (pkgs.writeShellApplication {207      name = "hsms";208      text = ''209        set -eu210        export OPENSSL_CONF=${openssl-conf}211        # Yay, using secrets to generate secrets!212        HSM_PIN=$(cat ${config.secrets.hsm-pin.secretPath})213        exec ${pkgs.openssl}/bin/openssl "$@" -keyform=engine -CAkeyform=engine -engine=pkcs11 -passin=pass:"$HSM_PIN"214      '';215    })216    (pkgs.writeShellApplication {217      name = "hsmt";218      text = ''219        set -eu220        HSM_PIN=$(cat ${config.secrets.hsm-pin.secretPath})221        exec ${pkgs.opensc}/bin/pkcs11-tool -l --pin="$HSM_PIN" "$@"222      '';223    })224  ];225  # And finally, I have secrets, which are shared between machines.226  # Note that this example is somewhat wrong, as this goes not into the machine configuration, but to fleet configuration.227  sharedSecrets = {228    "ca.pem" = {229      # This is just the public key, no need to regenerate it to change owner list230      regenerateOnOwnerAdded = false;231      # For secret regeneration/reencryption, we need to specify which machines SHOULD have it.232      expectedOwners = ["controlplane-1" "controlplane-2" "worker-1" "worker-2"];233      generator = {readKubernetesCa}:234        readKubernetesCa {235          impureOn = "[CENSORED]";236        };237    };238    "kube-admin.pem" = {239      regenerateOnOwnerAdded = false;240      expectedOwners = ["cluster-admin"];241      generator = {mkKubernetesCert}:242        mkKubernetesCert {243          subj = {244            CN = "admin";245            O = "system:masters";246          };247          impureOn = "[CENSORED]";248        };249    };250    "kube-apiserver.pem" = {251      # This secret depends on machine SANS, so if owner list has been changed, then we need to regenerate it.252      # However, SANS dependency is in fact handled by secret seed, and secret is regenerated if the seed is changed...253      #254      # In this case regeneration is added as a half-assed security measure, as if apiserver is removed, we don't255      # want for it to be able to pretend like it is a valid server.256      #257      # However, certificate revokation is complicated in my setup, and I can't show it here.258      regenerateOnOwnerAdded = true;259      expectedOwners = ["controlplane-1" "controlplane-2"];260      generator = {mkKubernetesCert}:261        mkKubernetesCert {262          inherit sans;263          subj.CN = "kubernetes";264          impureOn = "[CENSORED]";265        };266    };267}268----