Added dynamic inventory for AWS as contrib

contrib/aws_inventory/kargo-aws-inventory.py

+#!/usr/bin/env python
+
+import boto3
+import os
+import argparse
+import json
+
+class SearchEC2Tags(object):
+
+  def __init__(self):
+    self.parse_args()
+    if self.args.list:
+      self.search_tags()
+    if self.args.host:
+      data = {}
+      print json.dumps(data, indent=2)
+
+  def parse_args(self):
+
+    ##Check if VPC_VISIBILITY is set, if not default to private
+    if "VPC_VISIBILITY" in os.environ:
+      self.vpc_visibility = os.environ['VPC_VISIBILITY']
+    else:
+      self.vpc_visibility = "private"
+
+    ##Support --list and --host flags. We largely ignore the host one.
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--list', action='store_true', default=False, help='List instances')
+    parser.add_argument('--host', action='store_true', help='Get all the variables about a specific instance')
+    self.args = parser.parse_args()
+
+  def search_tags(self):
+    hosts = {}
+    hosts['_meta'] = { 'hostvars': {} }
+
+    ##Search ec2 three times to find nodes of each group type. Relies on kargo-role key/value.
+    for group in ["kube-master", "kube-node", "etcd"]:
+      hosts[group] = []
+      tag_key = "kargo-role"
+      tag_value = ["*"+group+"*"]
+      region = os.environ['REGION']
+
+      ec2 = boto3.resource('ec2', region)
+
+      instances = ec2.instances.filter(Filters=[{'Name': 'tag:'+tag_key, 'Values': tag_value}, {'Name': 'instance-state-name', 'Values': ['running']}])
+      for instance in instances:
+        if self.vpc_visibility == "public":
+          hosts[group].append(instance.public_dns_name)
+          hosts['_meta']['hostvars'][instance.public_dns_name] = {
+             'ansible_ssh_host': instance.public_ip_address
+          }
+        else:
+          hosts[group].append(instance.private_dns_name)
+          hosts['_meta']['hostvars'][instance.private_dns_name] = {
+             'ansible_ssh_host': instance.private_ip_address
+          }
+
+    hosts['k8s-cluster'] = {'children':['kube-master', 'kube-node']}
+    print json.dumps(hosts, sort_keys=True, indent=2)
+
+SearchEC2Tags()

docs/aws.md

@@ -8,3 +8,17 @@ Prior to creating your instances, you **must** ensure that you have created IAM
 The next step is to make sure the hostnames in your `inventory` file are identical to your internal hostnames in AWS. This may look something like `ip-111-222-333-444.us-west-2.compute.internal`. You can then specify how Ansible connects to these instances with `ansible_ssh_host` and `ansible_ssh_user`.
 
 You can now create your cluster!
+
+### Dynamic Inventory ###
+There is also a dynamic inventory script for AWS that can be used if desired. However, be aware that it makes some certain assumptions about how you'll create your inventory. 
+Guide:
+- Create instances in AWS as needed.
+- Add tags to the instances with a key of `kargo-role` and a value of `kube-master`, `etcd`, or `kube-node`. You can also share roles like `kube-master, etcd`
+- Copy the `kargo-aws-inventory.py` script from `kargo/contrib/aws_inventory` to the `kargo/inventory` directory.
+- Set the following AWS credentials and info as environment variables in your terminal:
+```
+export AWS_ACCESS_KEY_ID="xxxxx"
+export AWS_SECRET_ACCESS_KEY="yyyyy"
+export REGION="us-east-2"
+```
+- We will now create our cluster. There will be either one or two small changes. The first is that we will specify `-i inventory/kargo-aws-inventory.py` as our inventory script. The other is conditional. If your AWS instances are public facing, you can set the VPC_VISIBILITY variable to public and that will result in public IP and DNS names being passed into the inventory. This causes your cluster.yml command to look like `VPC_VISIBILITY="public" ansible-playbook ... cluster.yml`