Allow passing several labels to nixpkgs_package

.circleci/config.yml

@@ -10,9 +10,8 @@ jobs:
       - run:
           name: System dependencies
           command: |
-            export NIX_PATH=nixpkgs=$PWD/nix/default.nix
             apk update --no-progress && apk --no-progress add bash ca-certificates
-            nix-env -iA nixpkgs.bazel nixpkgs.gcc
       - run:
           name: Run tests
-          command: bazel test //...
+          command: |
+            nix-shell --pure --run 'bazel test //...'

README.md

@@ -34,7 +34,7 @@ nixpkgs_git_repository(
 
 nixpkgs_package(
     name = "hello",
-    repository = "@nixpkgs"
+    repositories = { "@nixpkgs": "nixpkgs" }
 )
 ```
 
@@ -160,8 +160,15 @@ nixpkgs clone in `nix_file` or `nix_file_content`.
       <td><code>repository</code></td>
       <td>
         <p><code>Label; optional</code></p>
-        <p>A Nixpkgs repository label. Specify one of `path` or
-		   `repository`.</p>
+        <p>Deprecated, use `repositories` instead.</p>
+      </td>
+    </tr>
+    <tr>
+      <td><code>repositorie</code></td>
+      <td>
+        <p><code>Label-keyed String dict; optional</code></p>
+        <p>A dictionary mapping repositoriy labels to `NIX_PATH` entries.
+        Specify one of `path` or `repositories`.</p>
       </td>
     </tr>
     <tr>
@@ -170,7 +177,7 @@ nixpkgs clone in `nix_file` or `nix_file_content`.
         <p><code>String; optional</code></p>
         <p>The path to the directory containing Nixpkgs, as
            interpreted by `nix-build`. Specify one of `path` or
-		   `repository`.</p>
+		   `repositories`.</p>
       </td>
     </tr>
     <tr>

WORKSPACE

@@ -4,44 +4,37 @@ load("//nixpkgs:nixpkgs.bzl", "nixpkgs_git_repository", "nixpkgs_package")
 
 # For tests
 
-nixpkgs_git_repository(
-  name = "nixpkgs",
-  revision = "17.09",
-  sha256 = "405f1d6ba523630c83fbabef93f0da11ea388510a576adf2ded26a744fbf793e",
-)
-
-nixpkgs_package(name = "hello", repository = "//:nix/default.nix")
+nixpkgs_package(name = "hello", repositories = { "nixpkgs": "//:nix/default.nix" })
 
 nixpkgs_package(
   name = "expr-test",
   nix_file_content = "let pkgs = import <nixpkgs> {}; in pkgs.hello",
-  repository = "//:nix/default.nix"
+  repositories = { "nixpkgs": "//:nix/default.nix" }
 )
 
 nixpkgs_package(
   name = "attribute-test",
   attribute_path = "hello",
-  repository = "//:nix/default.nix"
+  repositories = { "nixpkgs": "//:nix/default.nix" }
 )
 
 nixpkgs_package(
   name = "expr-attribute-test",
   nix_file_content = "import <nixpkgs> {}",
   attribute_path = "hello",
-  repository = "//:nix/default.nix",
+  repositories = { "nixpkgs": "//:nix/default.nix" },
 )
 
 nixpkgs_package(
   name = "nix-file-test",
   nix_file = "//tests:nixpkgs.nix",
   attribute_path = "hello",
-  repository = "//:nix/default.nix",
+  repositories = { "nixpkgs": "//:nix/default.nix" },
 )
 
 nixpkgs_package(
   name = "nix-file-deps-test",
   nix_file = "//tests:hello.nix",
   nix_file_deps = ["//tests:pkgname.nix"],
-  repository = "//:nix/default.nix",
+  repositories = { "nixpkgs": "//:nix/default.nix" },
 )
-

nixpkgs/nixpkgs.bzl

@@ -21,6 +21,15 @@ nixpkgs_git_repository = repository_rule(
 )
 
 def _nixpkgs_package_impl(ctx):
+  repositories = None
+  if ctx.attr.repositories:
+    repositories = ctx.attr.repositories
+
+  if ctx.attr.repository:
+    print("The 'repository' attribute is deprecated, use 'repositories' instead")
+    repositories = { ctx.attr.repository: "nixpkgs" } + \
+        (repositories if repositories else {})
+
   if ctx.attr.build_file and ctx.attr.build_file_content:
     fail("Specify one of 'build_file' or 'build_file_content', but not both.")
   elif ctx.attr.build_file:
@@ -31,7 +40,7 @@ def _nixpkgs_package_impl(ctx):
     ctx.template("BUILD", Label("@io_tweag_rules_nixpkgs//nixpkgs:BUILD.pkg"))
 
   strFailureImplicitNixpkgs = (
-     "One of 'path', 'repository', 'nix_file' or 'nix_file_content' must be provided. "
+     "One of 'path', 'repositories', 'nix_file' or 'nix_file_content' must be provided. "
      + "The NIX_PATH environment variable is not inherited.")
 
   expr_args = []
@@ -41,7 +50,7 @@ def _nixpkgs_package_impl(ctx):
     ctx.symlink(ctx.attr.nix_file, "default.nix")
   elif ctx.attr.nix_file_content:
     expr_args = ["-E", ctx.attr.nix_file_content]
-  elif not (ctx.attr.path or ctx.attr.repository):
+  elif not (ctx.attr.path or repositories):
     fail(strFailureImplicitNixpkgs)
   else:
     expr_args = ["-E", "import <nixpkgs> {}"]
@@ -66,17 +75,18 @@ def _nixpkgs_package_impl(ctx):
     "--out-link", "bazel-support/nix-out-link"
   ])
 
-  # If neither repository or path are set, leave empty which will use
+  # If neither repositories or path are set, leave empty which will use
   # default value from NIX_PATH, which will fail unless a pinned nixpkgs is
   # set in the 'nix_file' attribute.
   nix_path = ""
-  if ctx.attr.repository and ctx.attr.path:
-    fail("'repository' and 'path' attributes are mutually exclusive.")
-  elif ctx.attr.repository:
+  if repositories and ctx.attr.path:
+      fail("'repositories' and 'path' attributes are mutually exclusive.")
+  elif repositories:
     # XXX Another hack: the repository label typically resolves to
     # some top-level package in the external workspace. So we use
     # dirname to get the actual workspace path.
-    nix_path = str(ctx.path(ctx.attr.repository).dirname)
+    nix_path = ":".join([(path_name + "=" + str(ctx.path(path).dirname)) \
+                         for (path, path_name) in repositories.items()])
   elif ctx.attr.path:
     nix_path = str(ctx.attr_path)
   elif not (ctx.attr.nix_file or ctx.attr.nix_file_content):
@@ -94,7 +104,7 @@ def _nixpkgs_package_impl(ctx):
   timeout = 1073741824
 
   res = ctx.execute(nix_build, quiet = False, timeout = timeout,
-                    environment=dict(NIX_PATH="nixpkgs=" + nix_path))
+                    environment=dict(NIX_PATH=nix_path))
   if res.return_code == 0:
     output_path = res.stdout.splitlines()[-1]
   else:
@@ -106,21 +116,34 @@ def _nixpkgs_package_impl(ctx):
   _symlink_children(output_path, ctx)
 
 
-nixpkgs_package = repository_rule(
+_nixpkgs_package = repository_rule(
   implementation = _nixpkgs_package_impl,
   attrs = {
     "attribute_path": attr.string(),
     "nix_file": attr.label(allow_single_file = [".nix"]),
     "nix_file_deps": attr.label_list(),
     "nix_file_content": attr.string(),
     "path": attr.string(),
+    "repositories": attr.label_keyed_string_dict(),
     "repository": attr.label(),
     "build_file": attr.label(),
     "build_file_content": attr.string(),
   },
   local = True,
 )
 
+def nixpkgs_package(repositories, *args, **kwargs):
+    # Because of https://github.com/bazelbuild/bazel/issues/5356 we can't
+    # directly pass a dict from strings to labels to the rule (which we'd like
+    # for the `repositories` arguments), but we can pass a dict from labels to
+    # strings. So we swap the keys and the values (assuming they all are
+    # distinct).
+    inversed_repositories = { value: key for (key, value) in repositories.items() }
+    _nixpkgs_package(
+        repositories = inversed_repositories,
+        *args,
+        **kwargs
+    )
 
 def _symlink_children(target_dir, rep_ctx):
   """Create a symlink to all children of `target_dir` in the current

shell.nix

@@ -0,0 +1,11 @@
+{ pkgs ? import ./nix/default.nix {} }:
+
+with pkgs;
+
+mkShell {
+  buildInputs = [
+    bazel
+    gcc
+    nix
+  ];
+}