Extending OpenShift Origin: Build Your Own Cartridge with Bill DeCoste of Red Hat
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The document discusses OpenShift cartridges, which are technology stacks used to offer or customize services on the OpenShift platform. It outlines the history and evolution from cartridge v1.0 to v2.0, detailing the requirements, components, and functionalities necessary for implementing and managing cartridges effectively. Additional resources, quickstart examples, and communication channels for community support are also provided.
Extending OpenShift Origin: Build Your Own Cartridge with Bill DeCoste of Red Hat
- 1. OpenShift Community Day Writing Cartridges Bill DeCoste Principal Software Engineer wdecoste@redhat.com 1
- 2. Target Audience You... ● Wish to offer new user services on an OpenShift PaaS ● Customize an existing user service on a PaaS 2
- 3. What are Cartridges? ● Cartridge – A technology stack or framework (PHP, Perl, Java/JEE, Ruby, Python, MySQL, etc.) definition ● Plugin – Auth, DNS, etc. ● Gear – Allocation of memory, compute, and storage resources for running applications. Live on Nodes. ● Application – Instantiation of a Cartridge. Overloaded term, I know. ● Scaled/Scalable Application – Instantiated in multiple Gears 3
- 4. Suggestions ... ● Start with a DIY (More significant for Cart V1) – Resolve many installation and configuration issues (e.g. bindings, logging) ● Existing Quickstart or sample? ● Start with a similar cartridge – Apache based? – JEE Application Server? – Embeddable Database? 4
- 5. Requirements ● The OpenShift Cartridge API consists of: – Executable files – stdout/stderr – Environment variables ● You can use any language but we find bash the fastest – Bash “SDK” provided, other languages planned ● The software you are packaging either needs to be on the system or included in your cartridge 5
- 6. History – Cartridge V1.0 ● Opensource, but not easy to implement or customize – Overly large number of files/scripts – Blurred Node vs Cartridge responsibility (e.g. root access required by Cartridge) – Each version required a new Cartridge ● Difficult to maintain – APIs not versioned 6
- 7. History – Cartridge V2.0 ● Eased implementation, customization, and maintenance – Greatly reduced number of files/scripts – Well-defined Cartridge vs Node responsibility (e.g. root access not required by Cartridge) – Well-defined and versioned API – Multiple versions supported in single Cartridge ● Documentation: https://github.com/openshift/origin-server/blob/master/node/README.writing_cartridges.md 7
- 8. Minimal Cartridge +- bin | +- setup | +- control +- env +- metadata | +- manifest.yml *Assumes packaged software already installed on system *Most cartridges will have more files 8
- 9. metadata/manifest.yml ● Elements – Name – Version – Cartridge-Version – Cartridge-Vendor – Endpoints *Other elements for defining features of your cartridge and it's packaged software 9
- 10. Endpoints ● Cartridges must explicitly declare which ports they will bind to, and provide meaningful variable names to describe: – The IP address(es) reserved/available for binding – The Gear-local ports to which the cartridge services will bind – (Optional) Publicly proxied ports which expose Gear-local ports for use by the application's users or across application Gears Endpoints: - Private-IP-Name: <name of IP variable> (e.g. IP => OPENSHIFT_shortname_IP) Private-Port-Name: <name of port variable> (e.g. HTTP_PORT) Private-Port: <port number> (e.g. 8080) Public-Port-Name: <name of public port variable> (e.g. HTTP_PROXY_PORT) 10
- 11. Hooks (in-flux) ● Cartridges may need to act when some other cartridge is added/removed from an application. ● This functionality is supported using Publish/Subscribe connectors in the manifest.yml. Subscribes: set-mysql-connection-info: subscribe script Type: "NET_TCP:db:mysql" subscription key Publishes: publish-mysql-connection-info: publish script Type: "NET_TCP:db:mysql" subscription key 11
- 12. bin/setup ● Responsible for creating and/or configuring the files that were copied from the cartridge repository into the gear's directory. ● Option --version – Which version of the packaged software has been called for – Possible to support n versions of the software, allows reuse of like code/configuration files etc 12
- 13. bin/control OpenShift calls control when it wants work from you or your packaged software ● start – cartridge and the package software (httpd) ● stop – cartridge and the package software (mysqld) ● build – The application developer pushed new code to your language cartridge for processing (maven) ● deploy – Code compiled but application not yet started. (Update database) ● Others: threaddump, restart, reload, status 13
- 14. bin/teardown ● Prepares the gear for the cartridge to be removed. This script will not called when the gear is destroyed. ● The teardown script is only run when a cartridge is to be removed from the gear. ● The gear is expected to continue to operate minus the functionality of your cartridge. 14
- 15. Template ● Provides an minimal example of an application written in the language/framework your cartridge is packaging – Typically application to web applications (e.g. homepage) ● Action Hooks – Executables for custom lifecycle – e.g. pre-build, post-build, pre-deploy, post-deploy NOTE: Build lifecycle details available in doc ● Markers – Control cartridge behavior – e.g. hot_deploy, disable_auto_scaling, force_clean_build, java7 15
- 16. System Environmental Variables (in-flux) ● System Provided (subset) OPENSHIFT_APP_DNS the application's fully qualified domain name that your cartridge is a part of OPENSHIFT_APP_NAME the validated user assigned name for the application. Black list is system dependent. OPENSHIFT_APP_UUID OpenShift assigned UUID for the application OPENSHIFT_DATA_DIR the directory where your cartridge may store data OPENSHIFT_GEAR_DNS the gear's fully qualified domain name that your cartridge is a part of. May or may not be equal to OPENSHIFT_APP_DNS OPENSHIFT_GEAR_NAME OpenShift assigned name for the gear. May or may not be equal to OPENSHIFT_APP_NAME OPENSHIFT_GEAR_UUID OpenShift assigned UUID for the gear OPENSHIFT_HOMEDIR OpenShift assigned directory for the gear OPENSHIFT_REPO_DIR the directory where the developer's application is "archived" to and will be run from. OPENSHIFT_TMP_DIR the directory where your cartridge may store temporary data ● Cartridge Provided (examples) OPENSHIFT_MYSQL_DB_HOST OPENSHIFT_MYSQL_DB_PASSWORD OPENSHIFT_MYSQL_DB_PORT OPENSHIFT_MYSQL_DB_USERNAME 16
- 17. Installing a V2 Cartridge ● Typically available as RPMs ● Added to /usr/libexec/openshift/cartridges/v2 ● Install Cartridge: oo-admin-cartridge -a install -s /usr/libexec/openshift/cartridges/v2/XXX ● Clear Cache From /var/www/openshift/broker, run bundle exec rake tmp:clear OR Run `script/rails console` and enter 'Rails.cache.clear', ● Confirm rhc cartridge list 17
- 18. Quickstarts/Samples ● Many, many easy-to-install applications to showcase Cartridge use ● https://github.com/openshift ● Django, Rails, Tomcat, JEE, Mongo, Redmine, CakePHP, IronMQ, etc. ● Typically follow install pattern: rhc create app … cd app git remote add upstream … git pull -s recursive -X theirs upstream master ● Add your own! ● NOTE: Quickstarts blend of v1/v2. Not all tested vs V2 yet 18
- 19. Thank You! 19
- 20. Channels ● G+ Community https://plus.google.com/communities/114361859072744017486 ● E-Mail – OpenShift Users: users@lists.openshift.redhat.com – Origin Developers: dev@lists.openshift.redhat.com ● IRC: irc.freenode.net – OpenShift Users: #openshift – Origin Developers: #openshift-dev – Node/Cartridge Developers: #openshift-dev-node 20
- 21. Channels ● Forums http://openshift.redhat.com/community/forums/openshift ● Blogs https://openshift.redhat.com/community/blogs/ http://mattoncloud.org/ http://www.billdecoste.net http://www.krishnaraman.net http://cloud-mechanic.blogspot.com 21
- 22. OpenSource ● GitHub: https://github.com/openshift – Origin: origin-server – OSE: enterprise-server – Community Cartridges: origin-community-cartridges – Quickstarts, Examples – Watch, Star, Contribute!!! 22