OpenStack - assign security group to existing instance

Question

I want to assign a security group to an existing instance. Is this possible?

Answer 1

No, it isn't possible to assign a new security group to an instance that has already been started. However, changes to the rules of a security group do get propagated to running instances that belong to that group.

For example, if you launch an instance in the "default" security group, but you forgot to add the rule to allow ssh, you can add that rule to the "default" group and then you will be able to ssh to the running instance.

Answer 2

Create a new security group called new.

Get the id of your image (<image-id>)

select id from security_groups where name = 'new' ;
update security_group_instance_association set security_group_id=<security-group-id> where instance_id=<image-id> ;