allow binary caches for runner user

.github/workflows/test.yml

@@ -19,5 +19,6 @@ jobs:
       uses: ./
     - run: nix-build test.nix
     - run: nix-env -iA cachix -f https://github.com/NixOS/nixpkgs/tarball/ab5863afada3c1b50fc43bf774b75ea71b287cde
-    # cachix should be available
-    - run: which cachix
+    - run: cat /etc/nix/nix.conf
+    # cachix should be available and be able to configure a cache
+    - run: cachix use cachix

lib/main.js

@@ -30,6 +30,8 @@ function run() {
             yield exec.exec("sudo", ["sh", "-c", "echo http2 = false >> /etc/nix/nix.conf"]);
             // Set jobs to number of cores
             yield exec.exec("sudo", ["sh", "-c", "echo max-jobs = auto >> /etc/nix/nix.conf"]);
+            // Allow binary caches for runner user
+            yield exec.exec("sudo", ["sh", "-c", "echo trusted-users = root runner >> /etc/nix/nix.conf"]);
             // Catalina workaround https://github.com/NixOS/nix/issues/2925
             if (os_1.type() == "Darwin") {
                 yield exec.exec("sudo", ["sh", "-c", `echo \"nix\t${INSTALL_PATH}\"  >> /etc/synthetic.conf`]);

src/main.ts

@@ -1,8 +1,7 @@
 import * as core from '@actions/core';
 import * as exec from '@actions/exec';
 import * as tc from '@actions/tool-cache';
-import {homedir, userInfo, type} from 'os';
-import {existsSync} from 'fs';
+import {type} from 'os';
 
 async function run() {
   try {
@@ -16,6 +15,9 @@ async function run() {
     // Set jobs to number of cores
     await exec.exec("sudo", ["sh", "-c", "echo max-jobs = auto >> /etc/nix/nix.conf"]);
 
+    // Allow binary caches for runner user
+    await exec.exec("sudo", ["sh", "-c", "echo trusted-users = root runner >> /etc/nix/nix.conf"]);
+
     // Catalina workaround https://github.com/NixOS/nix/issues/2925
     if (type() == "Darwin") {
       await exec.exec("sudo", ["sh", "-c", `echo \"nix\t${INSTALL_PATH}\"  >> /etc/synthetic.conf`]);