Initial commit

.envrc

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+source_env ..
+use flake work#nix_actor

.gitignore

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+/.direnv

README.md

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+# Syndicated Nix Actor
+
+An actor for interacting with the [Nix](https://nixos.org/) daemon via the [Syndicated Actor Model](https://syndicate-lang.org/).
+
+*This is only a proof-of-concept and is not useful in any meaningful way.*
+
+## Example configuration
+```
+; create and publish a dedicated dataspace
+let ?nixspace = dataspace
+<nixspace $nixspace>
+
+$nixspace [
+  ; request a build of nixpkgs#hello
+  ? <nix-build "nixpkgs#hello" ?output> [
+    $log ! <log "-" { hello: $output }>
+  ]
+]
+
+; start nix_actor as a daemon
+<require-service <daemon nix_actor>>
+<daemon nix_actor {
+  argv: "/run/current-system/sw/bin/nix_actor"
+  protocol: application/syndicate
+}>
+
+; hand-off a capablity to the Nix dataspace to the actor
+? <service-object <daemon nix_actor> ?actor> [
+  $actor <serve $nixspace>
+]
+```

Tuprules.tup

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+NIM_FLAGS += --backend:cpp

nix_actor.nimble

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+# Package
+
+version = "20230326"
+author        = "Emery Hemingway"
+description   = "Syndicated Nix Actor"
+license       = "Unlicense"
+srcDir        = "src"
+bin           = @["nix_actor"]
+
+
+# Dependencies
+
+requires "nim >= 1.6.10", "syndicate >= 20230326"

protocol.prs

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+version 1 .
+
+Build = <nix-build @input string @output any> .
+Serve = <serve @cap #!any> .

src/Tupfile

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+include_rules
+: nix_actor.nim | $(SYNDICATE_PROTOCOL) ./<protocol> |> !nim_bin |>

src/nix_actor.nim

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+# SPDX-FileCopyrightText: ☭ Emery Hemingway
+# SPDX-License-Identifier: Unlicense
+
+import std/[asyncdispatch, json, osproc]
+import preserves, preserves/jsonhooks
+import syndicate
+from syndicate/protocols/dataspace import Observe
+import ./nix_actor/protocol
+import ./nix_actor/[main, store]
+
+type Observe = dataspace.Observe[Ref]
+
+proc build(spec: string): Build =
+  var execOutput = execProcess("nix", args = ["build", "--json", "--no-link", spec], options = {poUsePath})
+  stderr.writeLine execOutput
+  var js = parseJson(execOutput)
+  Build(input: spec, output: js[0].toPreserve)
+
+proc bootNixFacet(ds: Ref; turn: var Turn): Facet =
+  # let store = openStore()
+  inFacet(turn) do (turn: var Turn):
+    let storePathObservation = ?Observe(pattern: !Build) ?? {0: grabLit()}
+    during(turn, ds, storePathObservation) do (spec: string):
+      stderr.writeLine "build ", spec
+      let a = build(spec)
+      discard publish(turn, ds, a)
+
+proc bootNixActor(root: Ref; turn: var Turn) =
+  connectStdio(root, turn)
+  during(turn, root, ?Serve) do (ds: Ref):
+    discard bootNixFacet(ds, turn)
+
+initNix() # Nix lib isn't actually being used but it's nice to know that it links.
+bootDataspace("main", bootNixActor)
+runForever()

src/nix_actor/Tupfile

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+include_rules
+: ../../protocol.prs |> !preserves_schema_nim |> protocol.nim | ../<protocol>

src/nix_actor/main.nim

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+# SPDX-FileCopyrightText: ☭ Emery Hemingway
+# SPDX-License-Identifier: Unlicense
+
+{.passC: staticExec("pkg-config --cflags nix-main").}
+{.passL: staticExec("pkg-config --libs nix-main").}
+
+proc initNix*() {.importcpp: "nix::initNix", header: "shared.hh".}

src/nix_actor/protocol.nim

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+
+import
+  std/typetraits, preserves
+
+type
+  Serve* {.preservesRecord: "serve".} = object
+    `cap`* {.preservesEmbedded.}: Preserve[void]
+
+  Build* {.preservesRecord: "nix-build".} = object
+    `input`*: string
+    `output`*: Preserve[void]
+
+proc `$`*(x: Serve | Build): string =
+  `$`(toPreserve(x))
+
+proc encode*(x: Serve | Build): seq[byte] =
+  encode(toPreserve(x))

src/nix_actor/store.nim

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+# SPDX-FileCopyrightText: ☭ Emery Hemingway
+# SPDX-License-Identifier: Unlicense
+
+{.passC: staticExec("pkg-config --cflags nix-store").}
+{.passL: staticExec("pkg-config --libs nix-store").}
+
+{.passC: "'-DSYSTEM=\"x86_64-linux\"'".}
+
+type
+  StorePath {.importcpp: "nix::StorePath", header: "path.hh".} = object
+    discard
+
+proc isDerivation*(path: StorePath): bool {.importcpp.}
+
+type
+  Store {.importcpp: "nix::ref<nix::Store>", header: "store-api.hh".} = object
+    discard
+
+proc ensurePath*(store: Store; path: StorePath) {.importcpp.}
+
+proc openStore*(): Store {.importcpp: "nix::openStore".}

src/nix_actor/the_protocol.nim

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+
+import
+  std/typetraits, preserves
+
+type
+  Build* {.preservesRecord: "nix-build".} = object
+    `input`*: string
+    `output`*: string
+
+proc `$`*(x: Build): string =
+  `$`(toPreserve(x))
+
+proc encode*(x: Build): seq[byte] =
+  encode(toPreserve(x))