If you want to manage users with your OpsWorks installation, you can do it with Chef "user" recipes.

For example, if you want to change password for some user on all machines, the recipe is pretty simple:

user "deploy" do
password "PASS"
end

PASS can be generated with "openssl" tool:

#openssl passwd "PASS"

Please note that "user" recipe will require ruby-shadow gem, which NEEDS to be installed via chef-gem

chef_gem "ruby-shadow" do
action :install
end

If you install it via "package" recipe it won't work, for example:

package 'ruby-shadow' do
action :install
end