Avoid connecting with ansible before VM is ready by using a dummy remote-exec step

README.md

@@ -17,9 +17,19 @@ Application Credentials are tokens that can be used as an alternative to logging
 On EMBL's de.NBI OpenStack cloud visit the [Application Credentials](https://denbi.cloud.embl.de/dashboard/identity/application_credentials/) interface and create a new application credential providing only a name.
 You will then be presented with an `ID` and a `Secret` which you should use to configure terraform.
 
-Variables can be passed to terraform directly in the command-line or through environment variables.
+Variables can be passed to terraform directly in the command-line or through environment variables.  
 For convenience we'll be using environment variables.
 
+### SSH Authentication
+
+As a final step in the process of creating a VM, terraform will connect to it via SSH and, once successful, will start ansible, that will also connect via SSH.  
+For this process to work, you should have an `ssh-agent` running and `ssh-add` the private key that matches the public key specified in then `SSH_KEY` variable (see below for details).
+
+Both terraform and ansible will automatically use the ssh-agent to authenticate.  
+
+If this process doesn't work for you, make sure your `ssh-agent` doesn't have too many identities loaded.
+Consider retrying after deleting all identities (`ssh-add -D`) and `ssh-add` the specific private key.
+
 ### Required variables
 
 In addition to application credentials, the following variables need to be defined for terraform.

main.tf

@@ -118,6 +118,19 @@ resource "openstack_compute_floatingip_associate_v2" "floating_ip_1" {
   floating_ip = var.FLOATING_IP
   instance_id = "${openstack_compute_instance_v2.instance_1.id}"
 
+  # This dummy remote-exec will ensure that by the time we run ansible in the next
+  # local-exec provisioner, the machine is already up and responsive
+  provisioner "remote-exec" {
+    inline = ["uname -a"]
+
+    connection {
+      host        = self.floating_ip
+      type        = "ssh"
+      user        = "${var.IMAGE_ID.username}"
+      agent       = true
+    }
+  }
+
   provisioner "local-exec" {
     command = "ANSIBLE_HOST_KEY_CHECKING=False ansible-playbook --verbose -u '${var.IMAGE_ID.username}' -i '${self.floating_ip},' 'ansible/instance.yaml'"
   }