add multi-vm with corresponding floating ip example (terraform-provider-openstack#710)

* add multi-vm with corresponding floating ip example

This is an example how to spawn multiple openstack vm and automatically adding coresponding floating ips.

* reword according to the PR comments

* drop element usage in favor of index based notation

* parametrize the instance_prefix

Author: erickeller

examples/multiple-vm-with-floating-ip/Readme.md

@@ -0,0 +1,65 @@
+# Multiple Instances with Floating IPs
+
+## Prerequisites
+
+We assume you already installed terraform using the following instructions: https://www.terraform.io/downloads.html
+
+## Getting started
+
+First, download an openrc file from the OpenStack dashboard. If your cloud provider does not support downloading the openrc file from a dashboard, then you can use the openrc.sample file in this directory. Rename it to openrc and modify it using a text editor of your choice.
+
+After you have modified it, source it into your shell environment:
+
+```
+source ./openrc
+```
+
+Init providers
+
+```
+terraform init
+```
+
+
+## Deploy the Configuration
+
+plan the deployment
+
+```
+terraform plan
+# or with specific variables
+terraform plan -var 'pool=gateway' \
+                -var 'flavor=m02.c02.d20' \
+                -var 'count=3' \
+                -var 'network_name=my-network' \
+                -var 'ssh_key_file=./id_rsa_os'
+```
+
+Apply the plan
+
+```
+terraform apply -auto-approve
+# or with specific variables
+terraform apply -auto-approve \
+                -var 'pool=gateway' \
+                -var 'flavor=m02.c02.d20' \
+                -var 'count=3' \
+                -var 'network_name=my-network' \
+                -var 'ssh_key_file=./id_rsa_os'
+```
+
+
+## Tear down
+
+cleanup, watch the `-force` will not ask for any confirmation.
+
+```
+terraform destroy -force
+# or with specific variables
+terraform destroy -force \
+                -var 'pool=gateway' \
+                -var 'flavor=m02.c02.d20' \
+                -var 'count=3' \
+                -var 'network_name=my-network' \
+                -var 'ssh_key_file=./id_rsa_os'
+```

examples/multiple-vm-with-floating-ip/main.tf

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+resource "openstack_compute_keypair_v2" "terraform" {
+  name       = "terraform"
+  public_key = "${file("${var.ssh_key_file}.pub")}"
+}
+
+resource "openstack_compute_instance_v2" "multi" {
+  count = "${var.count}"
+  name = "${format("${var.instance_prefix}-%02d", count.index+1)}"
+  image_name = "${var.image}"
+  flavor_name = "${var.flavor}"
+  key_pair = "${openstack_compute_keypair_v2.terraform.name}"
+  security_groups = ["default"]
+  network {
+    name = "${var.network_name}"
+  }
+}
+
+resource "openstack_networking_floatingip_v2" "fip" {
+  count = "${var.count}"
+  pool = "${var.pool}"
+}
+
+resource "openstack_compute_floatingip_associate_v2" "fip" {
+  count       = "${var.count}"
+  instance_id = "${openstack_compute_instance_v2.multi.*.id[count.index]}"
+  floating_ip = "${openstack_networking_floatingip_v2.fip.*.address[count.index]}"
+}

examples/multiple-vm-with-floating-ip/openrc.sample

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+#!/usr/bin/env bash
+
+export OS_AUTH_URL=http://KEYSTONE.ENDPOINT.URL:5000/v3
+export OS_PROJECT_ID="42..."
+export OS_PROJECT_NAME="multivm-project"
+export OS_USER_DOMAIN_NAME="mycloud"
+export OS_PROJECT_DOMAIN_ID="23..."
+export OS_USERNAME="$USER"
+export OS_PASSWORD=$OS_PASSWORD_INPUT
+export OS_REGION_NAME="MyRegion"
+export OS_INTERFACE=public
+export OS_IDENTITY_API_VERSION=3

examples/multiple-vm-with-floating-ip/variables.tf

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+variable "image" {
+  default = "Ubuntu 18.04"
+}
+
+variable "flavor" {
+  default = "m1.small"
+}
+
+variable "ssh_key_file" {
+  default = "~/.ssh/id_rsa"
+}
+
+variable "ssh_user_name" {
+  default = "ubuntu"
+}
+
+variable "pool" {
+  default = "public"
+}
+
+variable "count" {
+  default = 2
+}
+
+variable "network_name" {
+  default = "my-network"
+}
+
+variable "instance_prefix" {
+  default = "multi"
+}