Cloning an Instance in AWS

  1. Make an AMI (Actions > Image > Create Image)
  2. AMI > Launch
    1. Protect termination
    2. Enable T2/T3 unlimited
    3. Storage: more for DB instance, less for BG instance.
    4. Security groups
      1. Allow SSH from all
      2. Allow all traffic from VPC (default VPC group)
  3. Don't set up elastic IP unless it's a web instance (AWS limits number of elastic IPs)
  4. Give instance a name like elmo-staging-db.
  5. Copy public IP and add to your ~/.ssh/config with helpful alias.
  6. If you are moving your background job processing to a different server, do sudo -u deploy crontab -r to delete the whenever-created crontab, which is no longer needed on this server.

Setting up DB Instance

Configure access to DB Instance

  1. sudo -u deploy crontab -r to delete the whenever-created crontab, no longer needed.
  2. sudo systemctl stop nginx && sudo systemctl disable nginx
  3. sudo vi /etc/postgresql/9.4/main/postgresql.conf and set listen_addresses = '*'
  4. sudo vi /etc/postgresql/9.4/main/pg_hba.conf and add these lines:
    # IPv4 remote connections:
host    all             all             0.0.0.0/0               md5
# IPv6 remote connections:
host    all             all             ::/0                    md5
    1. sudo systemctl restart postgresql
    2. Set password for deploy user in elmo_production database (on database instance, privileged user): sudo su - deploy psql elmo_production \password # and enter new password \quit exit

Setup DB connection on web instance

  1. Verify connection is possible: psql -h -U deploy elmo_production Enter the password. Console should open successfully.
  2. Edit config/database.yml and make it look something like this: default: &default adapter: postgresql encoding: utf8 pool: 5
    production:
  <<: *default
  database: elmo_production
  host: <DB_INST_PRIV_DNS>
  user: deploy
  password: "<DB_PASSWORD>"

    (Note quotes around password, just to be safe). 3. Restart nginx and ensure site still works. 4. Disable local postgres: sudo systemctl stop postgresql && sudo systemctl disable postgresql

Setting up background worker instance

  1. Clone app instance per instructions above.
  2. Do steps under "Setup DB connection on web instance" above.
  3. Disable local nginx: sudo systemctl stop nginx && sudo systemctl disable nginx
  4. Open rails console and ensure a basic query (e.g. User.count) works.

Sample Capistrano config

If using capistrano for deployment, configure something like this:

set :deploy_to, "/u/apps/elmo"
set :rbenv_custom_path, "/opt/rbenv"

set :whenever_roles, %i[bg] # Only deploy schedule.rb jobs to crontab on bg server(s).
set :delayed_job_roles, %i[bg] # Only deploy run delayed_job on bg server(s).
set :delayed_job_workers, 2

server "1.2.3.4", user: "deploy", roles: %i[app web]
server "1.2.3.5", user: "deploy", roles: %i[db]
server "1.2.3.6", user: "deploy", roles: %i[bg]