maxim

- name: ensure file exists at path
  shell: rsync -ci /source/path /destination/path
  register: rsync_result
  changed_when: "rsync_result.stdout != ''"

maxim

# Permissions cheatsheet

`chmod [a]bcd`

* bit a — sticky:1/setgid:2/setuid:4 (optional, default: 0)
* bit b — owner    | x:1/w:2/r:4 - xw:3/xr:5/wr:6/xwr:7
* bit c — group    | x:1/w:2/r:4 - xw:3/xr:5/wr:6/xwr:7
* bit d — everyone | x:1/w:2/r:4 - xw:3/xr:5/wr:6/xwr:7

note: only file/dir owner can chmod it

maxim

def authorize_key_for_root(config, *key_paths)
  [*key_paths, nil].each do |key_path|
    if key_path.nil?
      fail "Public key not found at following paths: #{key_paths.join(', ')}"
    end

    full_key_path = File.expand_path(key_path)

    if File.exists?(full_key_path)
      config.vm.provision 'file',

maxim

- name: ensure github.com is a known host
  lineinfile:
    dest: /root/.ssh/known_hosts
    create: yes
    state: present
    line: "{{ lookup('pipe', 'ssh-keyscan -t rsa github.com') }}"
    regexp: "^github\\.com"

maxim

- name: ensure postgresql hstore extension is created
  sudo: yes
  sudo_user: postgres
  shell: "psql {{ postgresql_database }} -c 'CREATE EXTENSION hstore;'"
  register: psql_result
  failed_when: >
    psql_result.rc != 0 and ("already exists" not in psql_result.stderr)
  changed_when: "psql_result.rc == 0"

maxim

Upon launch of custom base box intended as app behind load balancer:

1. [serf] join cluster, update lists
2. update local iptables
3. [serf] announce presence (already part of step 1?)
4. provision self (chef/ansible/docker/etc)
5. pull app (deploy to self from git, deb, docker, could be part of step 4?)
6. [serf] announce online

maxim

Problem	AWS	DigitalOcean
Network isolation	Private Cloud/Security Groups	tinc / n2n / freelan
Node initialization	CloudInit/User Data	?
Node discovery	EC2 API	Serf
Pull app on scale	More Like This	Serf
Distributed config	etcd	etcd

maxim

class Foo
  alias_method :bar,
  def foo
    :hello
  end
end
 
Foo.new.bar # => :hello

maxim

module Barney
  refine String do
    def wait_for_it(ending)
      replace(self + ending)
    end
  end
end

using Barney
"legen".wait_for_it "dary" # => "legendary"

maxim

echo "девуш\xD0:" | selecta

/Users/max/Executables/selecta:124:in `=~': invalid byte sequence in UTF-8 (ArgumentError)
  from /Users/max/Executables/selecta:124:in `block in matches'
	from /Users/max/Executables/selecta:124:in `select'
	from /Users/max/Executables/selecta:124:in `matches'
	from /Users/max/Executables/selecta:144:in `render'
	from /Users/max/Executables/selecta:134:in `render!'
	from /Users/max/Executables/selecta:37:in `block in main'
	from /Users/max/Executables/selecta:169:in `block in with_screen'