use s3fs for a node elasticbeanstalk app. Note the forked differences to the PHP one from @mattzuba - notably env vars are not available

03_s3fs.config

packages:
    yum:
        gcc: []
        libstdc++-devel: []
        gcc-c++: []
        fuse: []
        fuse-devel: []
        libcurl-devel: []
        libxml2-devel: []
        openssl-devel: []
        mailcap: []
        automake: []

sources:
    /tmp: https://github.com/s3fs-fuse/s3fs-fuse/archive/v1.78.zip

files:
    "/opt/elasticbeanstalk/bin/get_env_var":
        mode: "000755"
        owner: "root"
        group: "root"
        content: |
            #!/usr/bin/python
            import subprocess, json, sys

            if len(sys.argv) < 2:
                sys.exit('Usage: %s eb-env-key' % sys.argv[0])
            else:
                jsonstr = subprocess.check_output(['/opt/elasticbeanstalk/bin/get-config','environment'])
                ekeys = json.loads(jsonstr)
                print ekeys[sys.argv[1]]

    "/etc/fuse.conf" :
        mode: "000644"
        owner: root
        group: root
        content: |
            # mount_max = 1000
            user_allow_other

    "/opt/elasticbeanstalk/hooks/appdeploy/pre/11_unmount_s3fs.sh":
        mode: "000755"
        owner: root
        group: root
        content: |
            #!/usr/bin/env bash

            if mountpoint -q [/mnt/speechbubble-assets]; then
                fusermount -u [/mnt/speechbubble-assets]
            fi

    "/opt/elasticbeanstalk/hooks/appdeploy/enact/02_mount_s3fs.sh":
        mode: "000755"
        owner: root
        group: root
        content: |
            #!/usr/bin/env bash
            export AWS_ACCESS_KEY_ID=`/opt/elasticbeanstalk/bin/get_env_var AWS_ACCESS_KEY_ID`
            export AWS_SECRET_KEY=`/opt/elasticbeanstalk/bin/get_env_var AWS_SECRET_KEY`

            # Make sure it's mounted as the nodejs user
            uid=`id -u nodejs`
            gid=`id -g nodejs`
            s3fs speechbubble-assets /mnt/speechbubble-assets -o nonempty -o uid=$uid -o gid=$gid -o use_cache=/tmp -o allow_other -o default_acl=public-read

commands:
    01_create_dir:
        test: "[ ! -d /mnt/speechbubble-asset ]"
        command: "mkdir -p /mnt/speechbubble-assets && chown nodejs:nodejs /mnt/speechbubble-assets"

    02_patch_s3fs:
        cwd: /tmp/s3fs-fuse-1.78/src
        command: "sed -i 's/AWSACCESSKEYID/AWS_ACCESS_KEY_ID/g;s/AWSSECRETACCESSKEY/AWS_SECRET_KEY/g' s3fs.cpp"

    03_install_s3fs:
        cwd: /tmp/s3fs-fuse-1.78
        test: "[ ! -x /usr/bin/s3fs ]"
        command: "autoreconf --install && export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig && ./configure --prefix=/usr && make && make install"