3 Infrastructure as Code

Manage infrastructure (servers, load balancers, network) via configuration files that allows

• Configuration files describe a model of servers, network connections, load balancers, etc.,
• Configuration management tools interpret that model and “build” the infrastructure accordingly.

How can you “build” infrastructure automatically? A mixture of

• selecting & connecting to existing hardware
• using virtualization to simulate new hardware

3.1 Puppet

• Linux tool for automating config mgmt
• Master-client architecture
• Provides a declarative language, PuppetDSL, for describing desired configuration

case $operatingsystem {
  centos, redhat: { $service_name = 'ntpd' }
  debian, ubuntu: { $service_name = 'ntp' }
}

package { 'ntp':
  ensure => installed,
}

service { 'ntp':
  name      => $service_name,
  ensure    => running,
  enable    => true,
  subscribe => File['ntp.conf'],
}

file { 'ntp.conf':
  path    => '/etc/ntp.conf',
  ensure  => file,
  require => Package['ntp'],
  source  => "puppet:///modules/ntp/ntp.conf",
  # This source file would be located on the Puppet master at
  # /etc/puppetlabs/code/modules/ntp/files/ntp.conf
}

3.2 Chef

Systems administration tasks organized into “cookbooks” and “recipes”.

• Linux, Windows, cloud-friendly (AWS)
• Configurations are procedural in Ruby DSL
• Master-client

config.vm.box      = CFG_BOX
  config.vm.hostname = CFG_HOSTNAME

  config.vm.provider "virtualbox" do |v|
    v.name       = 'chef-automate'
    v.memory     = 8192
    v.cpus       = 4
    v.customize ['modifyvm', :id, '--audio', 'none']
  end

  config.vm.synced_folder '.', '/opt/a2-testing', create: true
  config.vm.network       'private_network', ip: CFG_IP
  config.vm.provision     'shell', env: {'CFG_IP' => CFG_IP,
                                         'CFG_HOSTNAME' => CFG_HOSTNAME,
                                         'ACCEPT_CHEF_TERMS_AND_MLSA' => AcceptLicense.new}, inline: $deployscript
end`

3.3 Ansible

• Written in Python, configuration based on YAML scripts
  • Still heavily procedural(?)
• Single-node architecture
  • Uses ssh to build artifact on target systems

3.4 Terraform

• Focus on provisioning, setting up servers before building the configuration
• Reputedly easier to use with Docker
• More declarative approach

4 Pipelines

Automation of continuous deployment is usually organized into pipelines.

• An assembly line of smaller stages.
  • The “pipeline” generally refers to both the tools and the collection of steps automated using those tools.
  • Typically include CI, automated (system) testing, report generation & continuous feedback (monitoring)
  • Does not necessarily map to “pipelines” as provided by GitHub & GitLab
    • Problem of passing artifacts from one stage to the next in a pipeline

Contrasting visions of pipelines

5 Monitoring

• Identify appropriate metrics
• Continuously collected
• Real-time analytics & reporting

Identifies both operational problems and provides feedback to Agile planning.

5.1 Elastic-Logstash-Kibana (ELK)