diff --git a/.mdeprc.js b/.mdeprc.js
index 9bc54e4..04e7b21 100644
--- a/.mdeprc.js
+++ b/.mdeprc.js
@@ -1,5 +1,4 @@
 /* eslint-disable no-template-curly-in-string */
-const execa = require('execa');
 
 module.exports = {
   nycCoverage: false,
@@ -27,8 +26,10 @@ module.exports = {
       },
     },
   },
+  euser: 'root',
+  tuser: 'node',
   arbitrary_exec: [
     'apk add git curl',
-    'npm i --global pnpm@6'
+    'wget -qO- https://get.pnpm.io/v6.16.js | node - add --global pnpm',
   ],
 };
diff --git a/bin/cmds/test.js b/bin/cmds/test.js
index b2d4b4d..e6d86cc 100644
--- a/bin/cmds/test.js
+++ b/bin/cmds/test.js
@@ -167,6 +167,16 @@ exports.builder = (yargs) => (
       type: 'boolean',
       default: false,
     })
+    .option('exec-user', {
+      alias: 'euser',
+      describe: 'user to run setup commands with',
+      type: 'string',
+    })
+    .option('test-user', {
+      alias: 'tuser',
+      describe: 'user to run test commands with',
+      type: 'string',
+    })
     .option('in-one', {
       alias: 'in_one',
       describe: 'runs all tests in 1 test runner',
diff --git a/bin/cmds/test_cmds/run.js b/bin/cmds/test_cmds/run.js
index 9956d9a..982b2d9 100644
--- a/bin/cmds/test_cmds/run.js
+++ b/bin/cmds/test_cmds/run.js
@@ -119,8 +119,8 @@ exports.handler = async (argv) => {
       bodyTimeout: 0,
     });
 
-    dockerExec = async (cmd, args, { stream = true, timeout = 0, assertCode = true } = {}) => {
-      const body = JSON.stringify({ file: cmd, args, timeout });
+    dockerExec = async (cmd, args, { stream = true, timeout = 0, assertCode = true, user } = {}) => {
+      const body = JSON.stringify({ file: cmd, args, timeout, user });
       debug(body);
       const res = await client.request({
         method: 'POST',
@@ -168,9 +168,11 @@ exports.handler = async (argv) => {
       return result;
     };
   } else {
-    dockerExec = async (cmd, args = [], { stream = true } = {}) => {
+    dockerExec = async (cmd, args = [], { stream = true, user } = {}) => {
       const command = `${cmd} ${args.join(' ')}`.trim();
-      const ex = execAsync('docker', ['exec', container, '/bin/sh', '-c', command], { buffer: !stream });
+      const argOpts = user ? ['--user', user] : [];
+      debug(command);
+      const ex = execAsync('docker', ['exec', ...argOpts, container, '/bin/sh', '-c', command], { buffer: !stream });
 
       if (stream) {
         ex.stdout.pipe(process.stdout);
@@ -186,13 +188,13 @@ exports.handler = async (argv) => {
     echo('rebuilding modules');
     for (const mod of argv.rebuild) {
       // eslint-disable-next-line no-await-in-loop
-      await dockerExec('npm', ['rebuild', mod]);
+      await dockerExec('npm', ['rebuild', mod], { user: argv.euser });
     }
   }
 
   if (argv.gyp) {
-    await dockerExec('node-gyp', ['configure']);
-    await dockerExec('node-gyp', ['build']);
+    await dockerExec('node-gyp', ['configure'], { user: argv.euser });
+    await dockerExec('node-gyp', ['build'], { user: argv.euser });
   }
 
   if (argv.sleep) {
@@ -240,14 +242,14 @@ exports.handler = async (argv) => {
   }
 
   await Promise.map(argv.pre, (cmd) => execa.command(cmd));
-  await Promise.map(argv.arbitrary_exec, (cmd) => dockerExec(cmd, undefined));
+  await Promise.map(argv.arbitrary_exec, (cmd) => dockerExec(cmd, undefined, { user: argv.euser }));
 
   const testCmds = argv.sort
-    ? Promise.each(testCommands, ([cmd, ...args]) => dockerExec(cmd, args))
-    : Promise.map(testCommands, ([cmd, ...args]) => dockerExec(cmd, args), { concurrency: argv.parallel || 1 });
+    ? Promise.each(testCommands, ([cmd, ...args]) => dockerExec(cmd, args, { user: argv.tuser }))
+    : Promise.map(testCommands, ([cmd, ...args]) => dockerExec(cmd, args), { user: argv.tuser, concurrency: argv.parallel || 1 });
   await testCmds;
 
-  await Promise.map(argv.post_exec, (cmd) => dockerExec(cmd));
+  await Promise.map(argv.post_exec, (cmd) => dockerExec(cmd, undefined, { user: argv.euser }));
 
   // upload codecoverage report
   if (argv.coverage) {
diff --git a/bin/runner.js b/bin/runner.js
old mode 100644
new mode 100755
index 124b37f..dc16eb5
--- a/bin/runner.js
+++ b/bin/runner.js
@@ -13,6 +13,7 @@ const Command = Type.Object({
   file: Type.String(),
   args: Type.Optional(Type.Array(Type.String({ minLength: 1 }))),
   timeout: Type.Optional(Type.Number({ default: 0 })),
+  user: Type.Optional(Type.String()),
 });
 
 const fastify = Fastify({
@@ -21,11 +22,23 @@ const fastify = Fastify({
 
 fastify.register(require('fastify-compress'));
 
+const uidCache = Object.create(null);
+const hasOwnProperty = Object.prototype.hasOwnProperty.bind(uidCache);
+
 fastify.post('/exec', { schema: { body: Command } }, async (request, reply) => {
-  const { file, args, timeout } = request.body;
+  const { file, args, timeout, user } = request.body;
+  const opts = { all: true, buffer: false, timeout };
+
+  if (user) {
+    if (!hasOwnProperty(user)) {
+      uidCache[user] = (await execa('id', ['-u', user])).stdout;
+    }
+    opts.user = uidCache[user];
+  }
+
   const subprocess = args
-    ? execa(file, args, { all: true, buffer: false, timeout })
-    : execa.command(file, { all: true, buffer: false, timeout });
+    ? execa(file, args, opts)
+    : execa.command(file, opts);
 
   reply.type('text/plain');