Add new resource: eni

Uses the aws-sdk gem, added as a dependency to metadata

metadata.rb

@@ -12,5 +12,7 @@
 supports 'ubuntu', '>= 14.04'
 supports 'debian', '>= 8.0'
 
+gem 'aws-sdk', '~> 3.0'
+
 depends 'modules', '>= 0.1.2'
 depends 'line', '~> 0.6.1'

resources/eni.rb

@@ -0,0 +1,121 @@
+require 'aws-sdk'
+require 'net/http'
+
+default_action :create_and_attach
+
+property :description,          String
+property :subnet_id,            String, required: true
+property :private_ip_address,   String
+property :security_groups,      Array
+property :network_interface_id, String
+
+action :create_and_attach do
+  nic_id_to_attach = network_interface_id || create
+
+  if attached_nic_ids.include? nic_id_to_attach
+    Chef::Log.debug "NIC with ID #{nic_id_to_attach} is already attached to #{instance_id}"
+  else
+    converge_by "Attach NIC #{nic_id_to_attach} to #{instance_id} at index #{next_device_index}" do
+      ec2.attach_network_interface(
+        network_interface_id: nic_id_to_attach,
+        instance_id: instance_id,
+        device_index: next_device_index
+      )
+    end
+  end
+end
+
+action :create do
+  create
+end
+
+action :delete do
+  if existing_nic
+    converge_by "Delete the NIC with ID #{existing_nic.network_interface_id}" do
+      ec2.delete_network_interface network_interface_id: existing_nic.network_interface_id
+    end
+  elsif network_interface_id
+    Chef::Log.debug "NIC with ID #{network_interface_id} does not exist"
+  else
+    Chef::Log.debug "NIC with description \"#{description}\" does not exist"
+  end
+end
+
+private
+
+def create
+  if existing_nic_id
+    Chef::Log.debug("NIC already exists: #{existing_nic.network_interface_id}/#{description}")
+    return existing_nic.network_interface_id
+  end
+
+  converge_by "Create new NIC in description: #{description}, subnet_id: #{subnet_id}" do
+    options = {}
+
+    %w(subnet_id private_ip_address security_groups).each do |prop|
+      next unless send prop
+      options[prop.to_sym] = send(prop)
+    end
+
+    ec2.create_network_interface(options).network_interface.network_interface_id
+  end
+end
+
+def existing_nic
+  @existing_nic ||= begin
+    # Use the ID to look up the adapter if we have it
+    return ec2.describe_network_interfaces(
+      network_interface_id: network_interface_id
+    ).network_interfaces.first if network_interface_id
+
+    # Otherwise use the description
+    results = ec2.describe_network_interfaces(
+      filters: [{ name: 'description', values: [description] }]
+    ).network_interfaces
+
+    # Multiple NICs with the same description == problems
+    if results.count > 1
+      fail "More than one NIC matches the description \"#{description}\": " \
+           "#{results.map(&:network_interface_id).join ', '}"
+    end
+
+    results.first
+  end
+end
+
+def ec2
+  @ec2 ||= AWS::EC2::Client.new
+end
+
+def instance_id
+  @instance_id ||= Net::HTTP.get URI 'http://169.254.169.254/2016-09-02/meta-data/instance-id'
+end
+
+def next_device_index
+  @next_device_index ||= begin
+    device_numbers = macs.map do |mac|
+      Net::HTTP.get(
+        URI "http://169.254.169.254/2016-09-02/meta-data/network/interfaces/macs/#{mac}/device-number"
+      ).to_i
+    end
+
+    device_numbers.sort.last + 1
+  end
+end
+
+def macs
+  @macs ||= Net::HTTP.get(
+    URI 'http://169.254.169.254/2016-09-02/meta-data/network/interfaces/macs/'
+  ).delete('/').split("\n")
+end
+
+def attached_nic_ids
+  @attached_nic_ids ||= begin
+    macs.map do |mac|
+      Net::HTTP.get(
+        URI "http://169.254.169.254/2016-09-02/meta-data/network/interfaces/macs/#{mac}" \
+            '/interface-id'
+      )
+    end
+  end
+end