{"id":195,"date":"2013-12-09T19:08:47","date_gmt":"2013-12-09T19:08:47","guid":{"rendered":"http:\/\/blogs.nd.edu\/devops\/?p=195"},"modified":"2013-12-09T21:00:26","modified_gmt":"2013-12-09T21:00:26","slug":"a-public-rails-instance-from-a-single-command","status":"publish","type":"post","link":"https:\/\/sites.nd.edu\/devops\/2013\/12\/09\/a-public-rails-instance-from-a-single-command\/","title":{"rendered":"A Public Rails App From Scratch in a Single Command"},"content":{"rendered":"

This weekend, I tweeted the public URL of an AWS instance. \u00a0Like most instances during this experimentation phase, it was not meant to live forever, so I’ll reproduce it here:<\/p>\n

_________________________________________________________________________________________________________
\n\"devops_intensifies\"<\/a><\/p>\n

This rails application was deployed to AWS with a single command. What happens when it runs?\u00a0<\/em><\/p>\n

    \n
  1. A shell script passes a CloudFormation template containing the instance and security group definitions to Boto.<\/em><\/li>\n
  2. Boto kicks off the stack creation on AWS.<\/em><\/li>\n
  3. A CloudInit script in the instance definition bootstraps puppet and git, then downloads repos from Github.<\/em><\/li>\n
  4. Puppet provisions rvm, ruby, and rails.<\/em><\/li>\n
  5. Finally, CloudInit runs Webrick as a daemon.<\/em><\/li>\n<\/ol>\n

    To do:\u00a0<\/em><\/p>\n

      \n
    1. Reduce CloudInit script to merely bootstrap Puppet.<\/em><\/li>\n
    2. Let Puppet Master and Capistrano handle instance and app provisioning, respectively.<\/em><\/li>\n
    3. Get better feedback on errors that may occur during this process.<\/em><\/li>\n
    4. Introduce an Elastic Load Balancer and set autoscale to 2.<\/em><\/li>\n
    5. Get a VPN tunnel to campus and access ND data<\/em><\/li>\n
    6. Work toward automatic app redeployments triggered by git pushes.<\/em><\/li>\n<\/ol>\n

      Onward!\u00a0<\/em><\/p>\n

      Brandon<\/em><\/p>\n

      _________________________________________________________________________________________________________<\/p>\n

      A single command, eh? It looks a bit like this:<\/p>\n

      .\/run_cloudformation.py us-east-1 MyTestStack cf_template.json brich tagfile<\/pre>\n
      Alright! \u00a0So let’s dig into exactly how it works. \u00a0All code can be found here in SVN<\/a>. \u00a0The puppet scripts and app are in my Github account, which I’ll link as necessary.<\/p>\n
      It starts with CloudFormation, as described in my post on that topic<\/a>. \u00a0The following template creates a security group, the instance, and a public IP. \u00a0This template<\/a> is called rails_instance_no_wait.json. \u00a0That’s because the Cloud Init tutorial<\/a> has you create this “wait handle” that prevents the CF console from showing “complete” until the provisioning part is done. \u00a0I’m doing so much in this step that I removed the wait handle to prevent a timeout. \u00a0As I mention below, this step could\/should be much more streamlined, so later we should be able to reintroduce this.<\/p>\n
      {\r\n  \"AWSTemplateFormatVersion\" : \"2010-09-09\",\r\n\r\n  \"Description\" : \"Creates security groups, an Amazon Linux instance, and a public IP for that instance.\",\r\n\r\n  \"Resources\" : {\r\n\r\n    \"SGOpenRailsToWorld\" : {\r\n      \"Type\" : \"AWS::EC2::SecurityGroup\",\r\n      \"Properties\" : {\r\n        \"GroupDescription\" : \"Rails web server access from SA-VPN\",\r\n        \"VpcId\" : \"vpc-1f47507d\",\r\n        \"SecurityGroupIngress\" : [ { \r\n        \t\"IpProtocol\" : \"tcp\", \r\n  \t\t\"CidrIp\" : \"0.0.0.0\/0\",\r\n\t\t\"FromPort\" : \"3000\", \r\n  \t\t\"ToPort\" : \"3000\"\r\n    \t} ]\r\n      }\r\n    },\r\n\r\n    \"BrandonTestInstance\" : {\r\n        \"Type\" : \"AWS::EC2::Instance\",\r\n        \"Properties\" : {\r\n            \"ImageId\" : \"ami-83e4bcea\",\r\n            \"InstanceType\" : \"t1.micro\",\r\n            \"KeyName\" : \"brich_test_key\",\r\n            \"SecurityGroupIds\" : [ \r\n                { \"Ref\" : \"SGWebTrafficInFromCampus\" },\r\n                { \"Ref\" : \"SGSSHInFromSAVPN\" },\r\n                { \"Ref\" : \"SGOpenRailsToWorld\" }\r\n            ],\r\n            \"SubnetId\" : \"subnet-4a73423e\",\r\n            \"Tags\" : [\r\n              {\"Key\" : \"Name\", \"Value\" : \"Brandon Test Instance\" },\r\n              {\"Key\" : \"Application\", \"Value\" : { \"Ref\" : \"AWS::StackId\"} },\r\n              {\"Key\" : \"Network\", \"Value\" : \"Private\" }\r\n            ],\r\n            \"UserData\" : \r\n            { \"Fn::Base64\" : { \"Fn::Join\" : [\"\",[\r\n            \"#!\/bin\/bash -ex\",\"\\n\",\r\n            \"yum -y update\",\"\\n\",\r\n            \"yum -y install puppet\",\"\\n\",\r\n            \"yum -y install subversion\",\"\\n\",\r\n            \"yum -y install git\",\"\\n\",\r\n            \"git clone https:\/\/github.com\/catapultsoftworks\/puppet-rvm.git \/usr\/share\/puppet\/modules\/rvm\",\"\\n\",\r\n            \"git clone https:\/\/github.com\/catapultsoftworks\/websvc-puppet.git \/tmp\/websvc-puppet\",\"\\n\",\r\n            \"puppet apply \/tmp\/websvc-puppet\/rvm.pp\",\"\\n\",\r\n            \"source \/usr\/local\/rvm\/scripts\/rvm\",\"\\n\",\r\n            \"git clone https:\/\/github.com\/catapultsoftworks\/cap-test.git \/home\/ec2-user\/cap-test\",\"\\n\",\r\n            \"cd \/home\/ec2-user\/cap-test\",\"\\n\",\r\n            \"bundle install\",\"\\n\",\r\n            \"rails s -d\",\"\\n\"\r\n ]]}}\r\n       }\r\n    },\r\n\r\n    \"PublicIPForTestInstance\" : {\r\n        \"Type\" : \"AWS::EC2::EIP\",\r\n        \"Properties\" : {\r\n            \"InstanceId\" : { \"Ref\" : \"BrandonTestInstance\" },\r\n            \"Domain\" : \"vpc\"\r\n        }\r\n    }\r\n\r\n  },\r\n\r\n\"Outputs\" : {\r\n    \"BrandonPublicIPAddress\" : {\r\n        \"Value\" : { \"Ref\" : \"PublicIPForTestInstance\" }\r\n    },\r\n\r\n    \"BrandonInstanceId\" : {\r\n        \"Value\" : { \"Ref\" : \"BrandonTestInstance\" }\r\n    }\r\n}\r\n\r\n}<\/pre>\n
      So we start with a security group. \u00a0This opens port 3000 (the default Rails port) to the world. \u00a0It could just have easily been opened to the campus IP range, the ES-VPN, or something else. \u00a0You’ll note that I am making reference to an already-existing VPC. \u00a0This is one of those governance things: VPCs and subnets are relatively permanent constructs, so we will just have to use IDs for static architecture like that. \u00a0Note that I have altered the ID for publication.<\/p>\n
      Please also notice that I have omitted an SSH security group! \u00a0Look ma, no hands!<\/em><\/p>\n
          \"SGOpenRailsToWorld\" : {\r\n      \"Type\" : \"AWS::EC2::SecurityGroup\",\r\n      \"Properties\" : {\r\n        \"GroupDescription\" : \"Rails web server access from SA-VPN\",\r\n        \"VpcId\" : \"vpc-1f37ab7d\",\r\n        \"SecurityGroupIngress\" : [ { \r\n        \t\"IpProtocol\" : \"tcp\", \r\n  \t\t\"CidrIp\" : \"0.0.0.0\/0\",\r\n\t\t\"FromPort\" : \"3000\", \r\n  \t\t\"ToPort\" : \"3000\"\r\n    \t} ]\r\n      }\r\n    },<\/pre>\n
      Next up is the instance itself. \u00a0Its parameters are pretty straightforward:<\/p>\n