Permission Error running `npm install` on elasticbeanstalk

I've managed to successfully create an Elastic Beanstalk app following the documentation.

The ember app itself is zipped and deployed to S3 via `ember-cli-deploy-elastic-beanstalk`, which the eb server manages to successfully download and unzip, however a permission error is logged when `fastboot-s3-downloader` tries to run `cd deploy-dist && npm install`:

```
No FASTBOOT_REDIS_HOST or FASTBOOT_REDIS_PORT provided; caching is disabled.
[2016-12-27T17:04:27.885Z][m3467] downloading app
[2016-12-27T17:04:27.886Z][m3467] fetching current app version from cb-ember-assets-staging/fastboot-dist.json
[2016-12-27T17:04:28.007Z][m3467] got config { bucket: 'cb-ember-assets-staging',
key: 'deploy-dist-be5a0f41c7886b05bfe3bbaa36f48985.zip' }
[2016-12-27T17:04:28.012Z][m3467] removing deploy-dist
[2016-12-27T17:04:28.023Z][m3467] saving S3 object cb-ember-assets-staging/deploy-dist-be5a0f41c7886b05bfe3bbaa36f48985.zip to deploy-dist-be5a0f41c7886b05bfe3bbaa36f48985.zip
[2016-12-27T17:04:28.234Z][m3467] unzipped deploy-dist-be5a0f41c7886b05bfe3bbaa36f48985.zip
[2016-12-27T17:04:28.881Z][m3467] error running command cd deploy-dist && npm install
[2016-12-27T17:04:28.881Z][m3467] npm WARN locking Error: EACCES: permission denied, open '/tmp/.npm/_locks/staging-f212e8d64a01707f.lock'
npm WARN locking at Error (native)
npm WARN locking /tmp/.npm/_locks/staging-f212e8d64a01707f.lock failed { Error: EACCES: permission denied, open '/tmp/.npm/_locks/staging-f212e8d64a01707f.lock'
npm WARN locking at Error (native)
npm WARN locking errno: -13,
npm WARN locking code: 'EACCES',
npm WARN locking syscall: 'open',
npm WARN locking path: '/tmp/.npm/_locks/staging-f212e8d64a01707f.lock' }
npm WARN deploy-dist No description
npm WARN deploy-dist No repository field.
npm WARN deploy-dist No license field.
npm ERR! Linux 4.4.35-33.55.amzn1.x86_64
npm ERR! argv "/opt/elasticbeanstalk/node-install/node-v6.9.1-linux-x64/bin/node" "/opt/elasticbeanstalk/node-install/node-v6.9.1-linux-x64/bin/npm" "install"
npm ERR! node v6.9.1
npm ERR! npm v3.10.8
npm ERR! path /tmp/.npm/_locks/staging-f212e8d64a01707f.lock
npm ERR! code EACCES
npm ERR! errno -13
npm ERR! syscall open

npm ERR! Error: EACCES: permission denied, open '/tmp/.npm/_locks/staging-f212e8d64a01707f.lock'
npm ERR! at Error (native)
npm ERR! { Error: EACCES: permission denied, open '/tmp/.npm/_locks/staging-f212e8d64a01707f.lock'
npm ERR! at Error (native)
npm ERR! errno: -13,
npm ERR! code: 'EACCES',
npm ERR! syscall: 'open',
npm ERR! path: '/tmp/.npm/_locks/staging-f212e8d64a01707f.lock' }
npm ERR!
npm ERR! Please try running this command again as root/Administrator.

npm ERR! Please include the following file with any support request:
npm ERR! /var/app/current/deploy-dist/npm-debug.log

[2016-12-27T17:04:28.881Z][m3467] unable to install npm dependencies
[2016-12-27T17:04:28.882Z][m3467] subscribing to update notifications
[2016-12-27T17:04:28.918Z][m3467] forked worker 3530
[2016-12-27T17:04:28.919Z][m3467] worker online
No FASTBOOT_REDIS_HOST or FASTBOOT_REDIS_PORT provided; caching is disabled.
[2016-12-27T17:04:29.697Z][w3530] starting HTTP server
[2016-12-27T17:04:29.708Z][w3530] HTTP server started; url=http://:::8081
```

The server is able to start regardless, because ember-deploy includes `node_modules` as part of `dist-deploy.zip`, but it would be nice to avoid this error.

A brute force solution would be to have `fastboot-s3-downloader` run `npm install` with `sudo`, but that probably should be avoided.

Would appreciate any help if anyone dealt with this issue as well.

Things tried so far that didn't work:
- [`mkdir ~/.npm-global ` && `NPM_CONFIG_PREFIX=~/.npm-global`](https://docs.npmjs.com/getting-started/fixing-npm-permissions)
- not including `node_modules` as part of `ember deploy` `dist-deploy.zip`