add a script to build a npm bin

prelude-nri/node/BUCK

@@ -39,3 +39,8 @@ export_file(
     name = "build_node_modules.py",
     visibility = ["PUBLIC"],
 )
+
+export_file(
+    name = "build_npm_bin.py",
+    visibility = ["PUBLIC"],
+)

prelude-nri/node/build_npm_bin.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+"""
+Make a independently-runnable npm binary.
+"""
+import argparse
+import os
+import stat
+import sys
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "node_modules",
+        help="The path to the node_modules you want to get binaries from.",
+    )
+    parser.add_argument(
+        "bin",
+        help="The binary to pull from node_modules",
+    )
+    parser.add_argument("out", help="Where you want the resulting binary.")
+    parser.add_argument(
+        "--bin-dir",
+        help="Path to a node installation's binary directory. If present, will be treated as an extra entry in PATH for the duration of this command.",
+    )
+
+    args = parser.parse_args()
+
+    if not os.path.exists(args.node_modules):
+        print("The given node_modules does not exist!")
+        sys.exit(1)
+
+    lines = [
+        "#!/usr/bin/env bash",
+        "set -e",
+    ]
+
+    bins = os.path.join(os.path.abspath(args.node_modules), ".bin")
+    path = [bins]
+    if args.bin_dir:
+        path.append(os.path.abspath(args.bin_dir))
+
+    lines.append("export PATH={}:$PATH".format(":".join(path)))
+
+    bin = os.path.join(bins, args.bin)
+    if not os.path.exists(bin):
+        print("The given binary does not exist!")
+        sys.exit(1)
+
+    lines.append(f"exec {bin} $@")
+
+    with open(args.out, "w") as fh:
+        fh.write("\n".join(lines))
+
+    os.chmod(
+        args.out,
+        stat.S_IRUSR
+        | stat.S_IXUSR
+        | stat.S_IRGRP
+        | stat.S_IXGRP
+        | stat.S_IROTH
+        | stat.S_IXOTH,
+    )

prelude-nri/node/toolchain.bzl

@@ -2,6 +2,7 @@ NodeToolchainInfo = provider(fields=[
     "bin_dir",
     "node",
     "build_node_modules",
+    "build_npm_bin",
 ])
 
 def _node_toolchain_impl(ctx) -> [[DefaultInfo.type, NodeToolchainInfo.type]]:
@@ -15,6 +16,7 @@ def _node_toolchain_impl(ctx) -> [[DefaultInfo.type, NodeToolchainInfo.type]]:
             bin_dir = ctx.attrs.bin_dir,
             node = ctx.attrs.node[RunInfo],
             build_node_modules = ctx.attrs._build_node_modules,
+            build_npm_bin = ctx.attrs._build_npm_bin,
         ),
     ]
 
@@ -31,6 +33,9 @@ node_toolchain = rule(
         "_build_node_modules": attrs.dep(
             default="prelude-nri//node:build_node_modules.py",
         ),
+        "_build_npm_bin": attrs.dep(
+            default="prelude-nri//node:build_npm_bin.py",
+        ),
     },
     is_toolchain_rule = True,
 )