Answer by asaf am for npm global install on elastic beanstalk

I managed to install pm2 globally on elastic beanstalk with the following code snippet embedded in an .ebextensions/your_file_name.config file

container_commands:  01_node_symlink:    command: "ln -sf `ls -td /opt/elasticbeanstalk/node-install/node-* | head -1`/bin/node /bin/node"  02_npm_symlink:    command: "ln -sf `ls -td /opt/elasticbeanstalk/node-install/node-* | head -1`/bin/npm /bin/npm"  03_pm2_install:    command: "if [ ! -e /bin/pm2 ]; then npm install pm2 -g; fi"    ignoreErrors: true