Run commands over SSH!

Sometimes I’ll need to run a few command on a remote machine. In the past, I would SSH into the machine and I would started making changes. But this is not ideal since this isn’t repeatable. If you’ve run into this problem, I have an alternative! You can execute a shell script from your local system and have it run commands on the remote system using SSH!

Please be aware that there are better tools – Ansible, Terraform, CloudFormation, etc. But those are heavy tools.

In this example, I have some configuration files that need to be copied to the remote system, and then I need to execute a couple commands. I also wanted the script to be checked into version control.

The first half of the script copies files, using scp, from my local machine to the remote machine. The second half of the script (starting on line 12) runs commands from the remote machine. The files are moved to the correct locations and Nginx and Haproxy are restarted.


scp -i ~/.ssh/$PEM ./surrogate_pop.conf ubuntu@$HOST:/tmp
scp -i ~/.ssh/$PEM ./haproxy.cfg ubuntu@$HOST:/tmp
scp -i ~/.ssh/$PEM ./traffic_cop.lua ubuntu@$HOST:/tmp
scp -i ~/.ssh/$PEM ./allowed_domains.lua ubuntu@$HOST:/tmp

## These are executed on the remote host
ssh -i ~/.ssh/$PEM ubuntu@$HOST 'bash -s' <<EOF
sudo mv /tmp/traffic_cop.lua /usr/share/nginx/traffic_cop.lua
sudo mv /tmp/allowed_domains.lua /usr/share/nginx/allowed_domains.lua
sudo mv /tmp/surrogate_pop.conf /etc/nginx/sites-enabled/surrogate_pop.conf
sudo service nginx restart

sudo mv /tmp/haproxy.cfg /etc/haproxy/haproxy.cfg
sudo service haproxy restart