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So Clojure walks into a

cloud...@tbatchelli

a.k.a. @disclojure

Oct 7th 2010

1Wednesday, October 13, 2010


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What?

Functionally deploy and manage yourapplications in the cloud, using the sameartifacts during all stages in the applicationlifecycle:

Development

Integration Tests

Production

Which cloud provider?- Any provider! All providers!



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What do they do?

jclouds manages the infrastructure in acloud-provider agnostic way

pallet sits both on above and belowjclouds to:- coordinate the infrastructure creation/

destruction/cycling- configure and manage the nodes



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jclouds

Templates abstractly describe nodes:- What OS to use, what versions...- What kind of hardware, what features are needed...

Tags organize identically configured nodes in groups You can create, destroy, reboot tags

- Also, manage keys pairs, security group config, etc...

Works across almost every cloud provider (see list)Note: jclouds does much more than what well seehere!

http://code.google.com/p/jclouds/http://code.google.com/p/jclouds/http://code.google.com/p/jclouds/


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REPL time!



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Pallet

High level management of node tags (groups) Setup and configuration of tags, even different

tags at once and in a coordinated way

Configuration of services in nodes, done viacrates, pre-packaged configuration elements.

Is agentless: uses vanilla images and does not

install any agent.

No central server either.



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pallet performs little things

Setup an admin account that you can use right awayfor ssh Install desired software on each node

Copy files to nodes Create and configure multi-node multi-serviceconfigurations (well see this)

... dunno, setup a fully configured --to your liking--hudson build manager?

Oh! and do all the above in usually done in oneshot, applied to as many nodes you want.



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Crates

Configuration components nagios, hudson, tomcat, couchdb, haproxy...* You customize crates by configuration, as

opposed to forking and editing them.

Complex crates are usually DSL Usually youll create your own lightweight crates

that will use standard crates* talk to Hugo Duncan if your favorite service is not yetsupported



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Webapp node(core/defnodewebapp"Basicwebapp,servedbytomcat"

{:os-family:ubuntu

:os-description-matches"10.04"

:inbound-ports[808022]}:bootstrap(resource/phase(crates/bootstrap))

:configure(resource/phase(crates/tomcat))

:deploy(resource/phase

(crates/tomcat-deploy"webapp.war"))

:restart-tomcat(resource/phase

(service/service"tomcat6"

:action:restart)))



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{:os-family:ubuntu








:action:restart)))



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{:os-family:ubuntu








:action:restart)))



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Alright, get it done

(pallet.core/converge

{webapp1}

:computeservice

:phase:deploy)



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How to deal withmulti-tag setups?



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proxied

(webapp)

proxied

(webapp)

proxied

(webapp)

HAproxy

the

lolcats-net



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two-phase model1. Invoke: for each phase (bootsrap,

configure, deploy, etc...), on all nodes of

each tag, call the crates. This generates:

- An intermediate representation of boththe particular and the global configuration- A list of the tasks to perform to setup the

nodes up to that configuration level needed

2. Execute all listed tasks based on the final

configuration created in the previous step



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the invoke step

foreachphase

foreachtag

foreachnodeintag

invoke-phaseonnodeintag



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the invoke step

Each phase, amongst other things, adds:

- New configuration data to the :parameters key- New resources to the :invocations key. These

resources are functions that will ultimately resultin a resource on the node (config file, script,

etc..)



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example

haproxy crate- Schedules the creation its configuration based

on the the proxied nodes added in :parameters

- the actual creation of the configuration will bedone in the next step

proxied crate

- for every proxied node it will create an entryin :parameters



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Proxy/Proxied

(core/defnodeproxied

"Aproxiedwebapp"

{:os-family:ubuntu


:inbound-ports[808022]}

:bootstrap(resource/phase(crates/bootstrap))

:configure(resource/phase(crates/tomcat)

(crates/reverse-proxy:haproxy

:app18080))

:deploy(resource/phase(crates/tomcat-deploy"mini-webapp.war"))



:action:restart)))



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Proxy/Proxied

(core/defnodehaproxy

"Simplehaproxy"

{:image-id"us-east-1/ami-6006f309"

:inbound-ports[8022]}:bootstrap(resource/phase

(crates/bootstrap))

:configure(resource/phase

(crates/haproxy))

:restart-haproxy(resource/phase

(service/service"haproxy":action:restart)))



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:parameters

{:haproxy


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:invocations{

....

:configure


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the execute step

foreachphase

foreachtag

foreachnodeintag

build-commands

execute-with-ssh



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the execute step

build the actual files and scripts to becreated and executed, based onthe :parameters

Execute the scripts on the node via ssh,

move files, etc...



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Proxy/Proxied

(pallet.core/converge

{proxied10haproxy1}

:computeservice

:phase:deploy)



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Notes on resources

Resources (files, scripts) are computed duringbuild time, but they are built at executiontime and on the node; this allows for variable

expansion based on the target node- i.e. $home/bin/java

Stevedore (also Hugo Duncans brain

child)builds bash scripts from a clojure DSL,with variable escaping similar to macros.Stevedore deserves a talk on its own.



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other notes

Easy to do dry-runs

- jclouds has a stub provider- pallet has a with-no-compute-service and wrap-

no-exec middleware

Easy to unit-test crates



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thank you

visit- www.pallet.org- www.jclouds.org

- #pallet on IRC- #jclouds on IRC- @hugoduncan on twitter- @jclouds on twitter- and ofcourse www.disclojure.org
http://www.jclouds.org/http://www.pallet.org/http://www.jclouds.org/http://www.jclouds.org/http://www.pallet.org/http://www.pallet.org/

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