Techniques for allowing your systems to share information with each other. Presented at the October Sydney DevOps Meetup

1. Sharing information between your systems
Michael Richardson @m_richo

2. Agenda
1.Chef Search
2.Puppet Exported Resources
3.PuppetDB query
4.Confd + etcd

3. Agenda
1.Chef Search
2.Puppet Exported Resources
3.PuppetDB query
4.Confd + etcd

5. Chef Server
Stores many useful things including
• Policies applied to nodes
• Metadata that describes each node
(ohai)
• And more…

6. Chef Server
This data is searchable!

7. Chef Server
This data is searchable!

8. Chef Server
This data is searchable!
But how?

9. Chef Server
1. ‘search’ method within recipe.
2. Search subcommand of ‘knife’
3. /search or /search/INDEX endpoints of Chef
Server API

10. Chef Server
1. ‘search’ method within recipe.
2. Search subcommand of ‘knife’
3. /search or /search/INDEX endpoints of Chef
Server API

11. Chef Server
Search within recipe – simple.

12. Chef Server
Search within recipe – simple.

13. Chef Server
Search within recipe – simple.

14. Chef Server
Search within recipe – simple.
It’s that simple

15. Chef Server
Search within recipe – more complex.

16. Chef Server
Chef Search is fantastic for
• Searching for nodes with particular
attributes
• Searching for nodes with particular profiles
• Using search results to configure services on
other nodes.

17. Chef Server
Common use cases
• My application talks to a database. What’s its FQDN/IP?
• How many memcache nodes are there for my application? What are
there FQDN/IPs?
• Where should I send my log files? What’s the FQDN of the syslog
server?
• I want to provide a white-list of IP’s that can request information from a
node.
• What are the IP addresses of the webservers behind my load balancer?
• My Jenkins slaves need to connect to a Jenkins master. What’s it’s IP?
• What are the SSH Host keys for particular hosts.

18. Agenda
1.Chef Search
2.Puppet Exported Resources
3.PuppetDB query
4.Confd + etcd

19. Exported Resources
Definition:
An exported resource declaration specifies a
desired state for a resource, does not manage the
resource on the target system, and publishes the
resource for use by other nodes. Any node
(including the node that exported it) can then
collect the exported resource and manage its own
copy of it. *
* https://docs.puppetlabs.com/puppet/latest/reference/lang_exported.html

20. Exported Resources
Think of it as
• Node(s) “publish” resources to the Puppet Master
• Other Node(s) consume those resources
* https://docs.puppetlabs.com/puppet/latest/reference/lang_exported.html

22. Exported Resources
Common Examples
• Backend servers configured in a load balancer
• Monitoring Servers updated with monitoring
clients (nagios_host / nagios_service)
• Distribute public keys (ssh and openssl)

23. Agenda
1.Chef Search
2.Puppet Exported Resources
3.PuppetDB query
4.Confd + etcd

24. PuppetDB
Definition:
collects data generated by Puppet. It enables
advanced Puppet features like the inventory service
and exported resources, and can be the foundation
for other applications that use Puppet’s data. *

25. PuppetDB
PuppetDB stores:
• The most recent facts from every node
• The most recent catalog for every node
• Optionally, 14 days of event reports for
every node
• Exported Resources

26. PuppetDB
PuppetDB stores:
• The most recent facts from every node
• The most recent catalog for every node
• Optionally, 14 days of event reports for
every node
• Exported Resources

27. PuppetDB
PuppetDB REST API
V3 API includes the following endpoints:
• Facts
• Resources
• Nodes
• Fact-names,
• Metrics
• Reports
• Events
• And more

28. PuppetDB

29. PuppetDB

30. PuppetDB
But this talk is about Node Collaboration.
How can I make use of this data?

31. PuppetDB
checkout
Puppetdbquery module
by Erik Dalén
https://forge.puppetlabs.com/dalen/puppetdbquery
https://github.com/dalen/puppet-puppetdbquery

32. PuppetDB
Puppetdbquery module
• Command line tools
• Puppet functions to query PuppetDB
• Hiera backend to return query results
from PuppetDB

33. PuppetDB
Puppetdbquery module
• Command line tools
• Puppet functions to query PuppetDB
• Hiera backend to return query results
from PuppetDB

34. PuppetDB
Puppetdbquery functions
• query_nodes
• query_facts

35. PuppetDB

36. PuppetDB
note: Output is abbreviated

37. PuppetDB
PuppetDBquery
• Works great and very similar to Chef
Search (searching for specific hosts, and
use their facts for configuring other
hosts).
• If you use Roles+Profiles pattern, this is
a fantastic fit for profiles.

38. Chef Search and PuppetDB are great!

39. Chef Search and PuppetDB are great!
but what if…

40. Chef Search and PuppetDB are great!
but what if…
• You want your infrastructure to react more quickly than
your Puppet agent / Chef-client run intervals (are you
even running the agents continuously).

41. Chef Search and PuppetDB are great!
but what if…
• You want your infrastructure to react more quickly than
your Puppet agent / Chef-client run intervals (are you
even running the agents continuously).
• You appreciate “desired state” AND “running state” aren’t
always the same thing.

42. Chef Search and PuppetDB are great!
but what if…
• You want your infrastructure to react more quickly than
your Puppet agent / Chef-client run intervals (are you
even running the agents continuously).
• You appreciate “desired state” AND “running state” aren’t
always the same thing.
• You don’t want to run a Puppet Master or Chef Server
(masterless Puppet / Chef-solo).

43. Chef Search and PuppetDB are great!
but what if…
• You want your infrastructure to react more quickly than
your Puppet agent / Chef-client run intervals (are you
even running the agents continuously).
• You appreciate “desired state” AND “running state” aren’t
always the same thing.
• You don’t want to run a Puppet Master or Chef Server
(masterless Puppet / Chef-solo).
• You don’t use Puppet or Chef. 

44. Agenda
1.Chef Search
2.Puppet Exported Resources
3.PuppetDB query
4.Confd + etcd

45. Confd
• “Lightweight configuration management tool”
• https://github.com/kelseyhightower/confd
• Written in go
• Manage local application configuration files using
templates and data from etcd or consul.

46. etcd
• Highly-available key/value store for shared
configuration and service discovery
• https://github.com/coreos/etcd
• Written in go
• Typical cluster size or 3-9 peers.
• CAP theorem

47. Confd + etcd
Distributed etcd cluster
etcd1
etcd2 etcd3 etcd4 etcd5
Hosts running applications
and services configured
with confd

48. Confd + etcd
• Hosts/Services that wish to share
information post data to etcd.
• Confd is configured on other hosts
to use this data to manage local
configuration files and services.

49. Confd + etcd
Distributed etcd cluster
etcd1
etcd2 etcd3 etcd4 etcd5
1 2
App server DB server
Example
1. App server runs Confd which is polling the following keys.
1. /myapp/db_ip
2. /myapp/db_port
3. /myapp/db_adapter
4. /myapp/db_name
2. Once up and running DB Server, writes details to etcd
cluster.
3. Confd reads key/values. Uses template file to write new
application configuration file and reloads application.

50. Confd + etcd
Demo
A “working” demo is worth a thousand powerpoint slides…

51. Summary
• Share information between your servers.
• Let them discover each other.
• Let your nodes collaborate with each
other.

52. Thank you