You normally think of virtualization as virtualization at the operating system level. But with Erlang, you can do virtualization at application level.

1. Erlang:
Bring cloud to your application
Ngoc Dao

2. Normally, you bring
your application → cloud
Erlang lets you bring
cloud → your application

3. Normally,
cloud is at OS level
Erlang lets you create and control
cloud at application level,
your application

4. It’s because Erlang feels like an OS
You can control the OS in your application

5. ps → pman:start().

6. top → etop:start().

7. applications → applications
appmon:start().
webtool:start().
observer:start().

8. “We are dropping appmon, and replacing it with observer instead.”

9. observer:start().

10. webtool alternative: BigWig

11. debugger:start().

12. Let’s create a cloud

13. Guest Guest
machine machine
mynode1 mynode2
Erlang process Erlang process
Erlang process Erlang process
Erlang process Erlang process
… …
Host
machine

14. Create 2 nodes
$ erl -sname mynode1 -setcookie mypassword1 -detached
$ erl -sname mynode2 -setcookie mypassword2 -detached

15. Check if the nodes are on
$ ps aux
Host
machine
Guest
[output] machine
epmd -daemon
beam.smp ... -sname mynode1 -setcookie mypassword1 -noshell -noinput
beam.smp ... -sname mynode2 -setcookie mypassword2 -noshell -noinput
Guest
machine

16. Guest Guest
machine machine
mynode1 mynode2
Erlang process Erlang process
Erlang process Erlang process
Erlang process Erlang process
… …
epmd Host
machine

17. Login to mynode1
$ erl -sname mynode3 -setcookie mypassword1 -remsh mynode1@ngoc
From here, to stop mynode1:
init:stop(). or q().
To quit without stoping mynode1:
Ctrl+C

18. More topics
• Deploy code to nodes
• Connect nodes together
• Hot code swap