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Introduction to Ansible - Jan 28 - Austin MeetUp
- 1. INTRODUCING ANSIBLE What is it? What do we do with it? How?! Tyler Turk
- 2. Uh… What are we talking about? • Configuration Management Utility • Automation Utility • Easily extensible and pluggable framework • Michael DeHaan, 2012 (developer of cobbler)
- 3. Please sir, may I have some more? • Written in Python • Used for server config management • Used for auditing of environment
- 4. Server-CM: Ansible 1.7.3 Masterchief: Ansible 0.9
- 6. What are inventories? What do they contain? • List of groups • List of hosts in groups • Potentially some variables
- 7. What’s our inventory? • Dynamic inventory interface based off server- meta • inventory/server_meta.py • Groups generated by: • server-meta-ranges • Datacenter values • ansible_groups property
- 8. Currently Extant Groups • 64b-pod • hapod • 4g • 8g-legacy • development • staging • production • protostaging • vendor_group • cloud • dedicated • clusters
- 9. Managing Disparate Environments • Primary API services production • Dev API services development • Corporate servers are handled with a flat file
- 10. Why is the inventory important? • Groups are managed by dynamic inventory • Skipping dynamic inventory means no groups • No groups means incorrect variables set • Systems will be configured incorrectly
- 11. Why do we need a custom inventory? • Multi-vendor strategy • Custom data requirements • Assurance of environment isolation
- 13. Access The Servers You Want! • ‘pod-*’ # All pods • ‘utility-*’ # All servers with utility in the name • ‘cluster-*:!dbmaster*’ # All servers in each cluster excluding dbmaster • ‘vendor:&pod-*’ # All pods that exist in vendor
- 14. A simple example
- 15. Another example with explicit inclusion
- 17. What is idempotence? f(x) = f(f(x)) = f(f(f(f(f(f(x)))))) • property of certain operations in mathematics and computer science, that can be applied multiple times without changing the result beyond the initial application •f(x) = f(f(x))
- 18. Okay… why do we care? • Less accident prone • We don’t break things • Playbook is repeatable • Helps to ensure same state, each time
- 19. Examples • Idempotent Task: lineinfile: dest=/etc/hosts line=“127.0.01 localhost” state=present • Non-Idempotent Task: shell: echo “127.0.01 localhost” >> /etc/hosts
- 20. AD-HOC USAGE
- 21. Ansible Runner Welcome to Ad-Hoc Usage
- 22. Useful Modules • Apt • Command • Copy • Fetch • File • Service • Shell • Stat • Template • User • Zabbix Maintenance
- 23. Issues with Bash-isms • Complex audits can require mixed quotations • Susceptible to shell limitations • Use python wrapper to avoid bash-isms
- 24. Command Examples ansible -i inventory/server_meta.py -m shell -a ‘ls /nas/local/ssl’ vendor ansible -f 50 -m shell -a 'grep mysql.heartbeat /etc/zabbix/zabbix_agentd.conf | wc -l' -i inventory/server_meta.py 'cluster*' &>heart.out ansible -f 50 -m copy -a "src=/root/ssl_sucks/cloudflare.conf dest=/etc/wpengine/nginx/ssl.d/cloudflare.conf owner=root group=root mode=0644" -i inventory/server_meta.py 'pod-*:hapod-*:web-*'
- 25. WHAT IS THIS PLAYBOOK SORCERY?
- 26. What are playbooks? • List of tasks • Run against subset of hosts • Hopefully idempotent
- 27. What’s in a playbook? • Conditional task execution • Hosts • Notifiable handlers • Roles • Variables
- 28. Example Playbook
- 29. Server Provisioning Playbooks • Remote Playbook: • Executed remotely • Handles partitioning • Initial Configuration • Copies files out • Platform Playbook: • Executed locally • Facts from remote • Ensures packages • Completes Config
- 30. Platform Deployment Playbook • phased-deploy: • git prefetch • git checkout • ensures consistent phases
- 31. One-Off Playbooks • build-server.yml • Handles build server provisioning • fire_and_forget_pull.yml • Similar to nas2-prefetch.yml • prepare-loadtest.yml • Stages the droid install on a server • remove_user.yml • Removes user from our infrastructure
- 33. Introduction to Ansible Variables • Regular variables: Variables that are explicitly defined either via register or various files / CLI options • Magic variables: Variables that are defined automatically
- 34. Some Magic Variables • hostvars • ansible_distribution • ansible_INTERFACE • ansible_fqdn • ansible_pkg_mgr • group_names • inventory_hostname
- 35. Variable Precedence • Defined on the CLI (-e, --extra-vars) • Connection variables • “Most everything else” • Inventory variables • Discovered facts • Role defaults
- 36. Wait… “most everything else…?” • Included variables • Host variables • Group Variables • Child group • Parent group • “All” variables, the super parent • Define a variable as few times as possible
- 37. Using Lookup Plugins for Variables • with_items - Iterate through a list of items • with_dict - Iterate through a dictionary • with_fileglob - Iterate through a glob of files • with_first_found - Iterate through files until one is found • Create your own!
- 39. Introduction to Templating group_vars/all: is_vagrant: false roles/common/templates/etc/hosts: {% if is_vagrant %} 192.168.1.1 api.wpengine.com {% endif %}
- 40. How to Loop in Templates roles/common/templates/etc/hosts: {% for ip in ansible_all_ipv4_addresses | sort %} {{ ip }} {{ ansible_fqdn }} {% endfor %} roles/common/templates/etc/ansible_groups: {% for name in group_names | sort %} {{ name }} {% endfor %}
- 41. Conditionals and Extensions roles/apache/templates/var/www/index.jn2: <html><head> {% if maintenance_mode | default('', false) | bool %} {% include "maintenance_header.html" %} {% else %} <title>Production - Ansible Example</title></head><body> <h3>Production mode FTW!</h3> {% endif %} </body></html>
- 42. Simple Demo Time! ansible-playbook sample.yml ansible-playbook sample.yml -e "maintenance_mode=false" ansible-playbook sample.yml -e “maintenance_mode=true" file:///Users/tylerturk/meetup/output/index.html
- 43. I WANT MORE OUT OF IT
- 44. Possible to Extend Upon • Additional plugins can easily be dropped in • Researching sample plugins goes a long way • Several different plugin types currently available • Return results in JSON or hook however you choose
- 45. Got questions? Ask! Examples Available At: https://github.com/tylerturk/ansible-examples- jan28 Twitter: tylerjturk