Exploratory: Add bootstrap script hook

nix/eval-machine-info.nix

@@ -305,7 +305,7 @@ rec {
 
     machines =
       flip mapAttrs nodes (n: v': let v = scrubOptionValue v'; in
-        { inherit (v.config.deployment) targetEnv targetPort targetHost encryptedLinksTo storeKeysOnMachine alwaysActivate owners keys hasFastConnection;
+        { inherit (v.config.deployment) targetEnv targetPort targetHost encryptedLinksTo storeKeysOnMachine alwaysActivate owners keys hasFastConnection bootstrapScript;
           nixosRelease = v.config.system.nixos.release or v.config.system.nixosRelease or (removeSuffix v.config.system.nixosVersionSuffix v.config.system.nixosVersion);
           azure = optionalAttrs (v.config.deployment.targetEnv == "azure")  v.config.deployment.azure;
           ec2 = optionalAttrs (v.config.deployment.targetEnv == "ec2") v.config.deployment.ec2;

nix/options.nix

@@ -57,6 +57,16 @@ in
       '';
     };
 
+    deployment.bootstrapScript = mkOption {
+      type = types.nullOr types.lines;
+      default = null;
+      description = ''
+        This option specifies an optional bash script to be run on the target
+        before nix-specific operations are run. It only assumes `bash` to be
+        installed on the target.
+      '';
+    };
+
     deployment.targetPort = mkOption {
       type = types.int;
       description = ''

nixops/backends/none.py

@@ -21,6 +21,9 @@ def __init__(self, xml, config):
         public_ipv4 = xml.find("attrs/attr[@name='publicIPv4']/string")
         self._public_ipv4 = None if public_ipv4 is None else public_ipv4.get("value")
 
+        bootstrap_cript = xml.find("attrs/attr[@name='bootstrapScript']/string")
+        self._bootstrap_script = None if bootstrap_cript is None else bootstrap_cript.get("value")
+
 class NoneState(MachineState):
     """State of a trivial machine."""
 
@@ -30,6 +33,7 @@ def get_type(cls):
 
     target_host = nixops.util.attr_property("targetHost", None)
     public_ipv4 = nixops.util.attr_property("publicIpv4", None)
+    bootstrap_script = nixops.util.attr_property("bootstrapScript", None)
     _ssh_private_key = attr_property("none.sshPrivateKey", None)
     _ssh_public_key = attr_property("none.sshPublicKey", None)
     _ssh_public_key_deployed = attr_property("none.sshPublicKeyDeployed", False, bool)
@@ -52,6 +56,7 @@ def create(self, defn, check, allow_reboot, allow_recreate):
         self.set_common_state(defn)
         self.target_host = defn._target_host
         self.public_ipv4 = defn._public_ipv4
+        self.bootstrap_script = defn._bootstrap_script
 
         if not self.vm_id:
             self.log_start("generating new SSH keypair... ")

nixops/deployment.py

@@ -1004,6 +1004,8 @@ def worker(r):
 
         if build_only or dry_run: return
 
+        self.bootstrap_resources()
+
         # Copy the closures of the machine configurations to the
         # target machines.
         self.copy_closures(self.configs_path, include=include, exclude=exclude,
@@ -1229,6 +1231,18 @@ def worker(m):
 
         nixops.parallel.run_tasks(nr_workers=-1, tasks=self.active.itervalues(), worker_fun=worker)
 
+    def bootstrap_resources(self):
+
+        def worker(r):
+            if is_machine(r):
+                if r.bootstrap_script is not None:
+                    r.run_command(r.bootstrap_script)
+
+        nixops.parallel.run_tasks(
+            nr_workers=-1,
+            tasks=iter(self.active_resources.values()),
+            worker_fun=worker,
+        )
 
 def should_do(m, include, exclude):
     return should_do_n(m.name, include, exclude)