OpenShift Origin Community Day (Boston) Extending OpenShift Origin: Build Your Own Cartridge V2 by Jhon Honce
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The document discusses the process of writing cartridges for OpenShift, detailing the roles of application developers, PaaS developers, and cartridge authors. It provides insights into the structure and components of a cartridge, including required files, environment variables, and communication protocols for databases. Additionally, it includes tips for creating applications and resources for further information on cartridge development.
OpenShift Origin Community Day (Boston) Extending OpenShift Origin: Build Your Own Cartridge V2 by Jhon Honce
- 1. Writing Cartridges for OpenShift Jhon Honce Pr Software Engineer, Red Hat Inc OpenShift Origin Community Day (Boston) June 13, 2013 http://openshift.github.io
- 2. The OpenShift Ecosystem: GUI/CLI, Broker, Node GUI rhc (CLI) Broker Node (Cartridges) REST API ssh|git MCollective snapshot.tgz gitrepository
- 3. Where does my code fit? ● Application – application developer ● Gears – PaaS developer ● Cartridges – Cartridge authors ● Web Frameworks, Databases, Daemons ● Encapsulates some piece software for use within the PaaS
- 4. The Cartridge API ● Low overhead ● Named executable files ● stdout/stderr ● Environment variables ● Configuration files: manifest.yml, managed_files.yml ● You can use any language ● source $OPENSHIFT_CARTRIDGE_SDK_BASH ● The software you are packaging must either be on the system or included in your cartridge
- 5. Minimal Cartridge – identify cartridge +- bin | +- setup | +- control +- env +- metadata | +- manifest.yml ● Assumes packaged software already installed on system ● Most cartridges will have more files ● manifest.yml Name: dog Cartridge-Short-Name: DOG . : Version: ‘1.0’ Cartridge-Version: 0.0.1 Cartridge-Vendor: honce
- 6. Minimal Cartridge – required files +- bin | +- setup | +- control +- env +- metadata | +- manifest.yml ● Assumes packaged software already installed on system ● Most cartridges will have more files ● manifest.yml Name: dog Cartridge-Short-Name: DOG . : Version: ‘1.0’ Cartridge-Version: 0.0.1 Cartridge-Vendor: honce
- 7. Minimal Cartridge +- bin | +- setup | +- control +- env +- metadata | +- manifest.yml ● Assumes packaged software already installed on system ● Most cartridges will have more files ● manifest.yml Name: dog Cartridge-Short-Name: DOG . : Version: ‘1.0’ Cartridge-Version: 0.0.1 Cartridge-Vendor: honce
- 8. My Cartridge needs to be seen! +- bin | +- … | +- control +… ● control Arguments ● start ● stop ● manifest.yml . : Endpoints: - Private-IP-Name: IP Private-Port-Name: PORT Private-Port: 8080 Public-Port-Name: PROXY_PORT Mappings: - Frontend: "" Backend: "" ● Environment Variables OPENSHIFT_<SHORT_NAME>_IP OPENSHIFT_<SHORT_NAME>_PORT OPENSHIFT_…_PROXY_PORT
- 9. My Cartridge needs to be invoked +- bin | +- … | +- control +… ● Basic control arguments ● start ● stop ● manifest.yml . : Endpoints: - Private-IP-Name: IP Private-Port-Name: PORT Private-Port: 8080 Public-Port-Name: PROXY_PORT Mappings: - Frontend: "" Backend: ""
- 10. My Cartridge needs to be seen! +- bin | +- … | +- control +… ● Basic control arguments ● start ● stop ● manifest.yml . : Endpoints: - Private-IP-Name: IP Private-Port-Name: PORT Private-Port: 8080 Public-Port-Name: PROXY_PORT Mappings: - Frontend: "" Backend: ""
- 11. Tip: control script can be trivial . : case “$1” in start) /usr/sbin/httpd -C "Include $OPENSHIFT_DOG_CONF_DIR/*.conf" -f $HTTPD_CFG_FILE -k start ;; stop) … -k stop ;; restart) … -k restart ;; esac
- 12. My Cartridge needs help, a database cartridge +- hooks | +- … | +- publish-db-connection-info +… ● manifest.yml . : Publishes: publish-db-connection-info: Type: "ENV:NET_TCP:db:connection-info" ● Pub/Sub Protocol ● publish-db-connection-info is a script echo OPENSHIFT_MYSQL_DB_HOST=$OPENSHIFT_GEAR_DNS echo OPENSHIFT_MYSQL_DB_PORT=$OPENSHIFT_MYSQL_DB_PROXY_PORT echo OPENSHIFT_MYSQL_DB_URL=”mysql://…/”
- 13. My Cartridge needs help, a database cartridge! ● manifest.yml . : Publishes: publish-db-connection-info: Type: "ENV:NET_TCP:db:connection-info" ● Publish/Subscribe Protocol ● publish-db-connection-info is a script echo OPENSHIFT_MYSQL_DB_HOST=$OPENSHIFT_GEAR_DNS echo OPENSHIFT_MYSQL_DB_PORT=$OPENSHIFT_MYSQL_DB_PROXY_PORT echo OPENSHIFT_MYSQL_DB_URL=”mysql://…/”
- 14. My Cartridge needs needs to be listening ● Pub/Sub Protocol ● The Type: element determines both the message format and whether the subscribe hook may be implemented in the Platform ● A provided hook script will be run in place of Platform code ● manifest.yml . : Subscribes: set-db-connection-info: Type: “ENV:NET_TCP:db:connection-info” Required: false
- 15. Let the Platform the cartridge can use a database ● Pub/Sub Protocol ● The Type: element determines both the message format and whether the subscribe hook may be implemented in the Platform ● A provided hook script will be run in place of Platform code ● manifest.yml . : Subscribes: set-db-connection-info: Type: “ENV:NET_TCP:db:connection-info” Required: false
- 16. Let the Platform the cartridge can use a database ● Pub/Sub Protocol ● The Type: element determines both the message format and whether the subscribe hook may be implemented in the Platform ● A provided hook script will be run in place of Platform code ● manifest.yml . : Subscribes: set-db-connection-info: Type: “ENV:NET_TCP:db:connection-info” Required: false
- 17. My Cartridge needs to be listening for databases ● Pub/Sub Protocol ● The Type: element determines both the message format and whether the subscribe hook may be implemented in the Platform ● A provided hook script will be run in place of Platform code ● manifest.yml . : Subscribes: set-db-connection-info: Type: “ENV:NET_TCP:db:connection-info” Required: false
- 18. My Cartridge needs to be listening for databases ● Pub/Sub Protocol ● The Type: element determines both the message format and whether the subscribe hook may be implemented in the Platform ● A provided hook script will be run in place of Platform code ● manifest.yml . : Subscribes: set-db-connection-info: Type: “ENV:NET_TCP:db:connection-info” Required: false
- 19. Customize Work Flows ● Cartridge Authors ● Implement additional control actions ● Provide optional scrips ● Application Developers ● .openshift/action_hooks ● .openshift/markers ● git pushed from developers repository
- 20. For Language Frameworks: A sample application ● template directory ● Checked in as the gear's initial git repository ● A “complete” application demonstrating that your cartridge is ready for business ● If you should add the manifest element: ● Install-Build-Required: false ● Speeds up the installation of your cartridge ● You need to do work for the application developer
- 21. Environment Variables The Node/Application/Gear/Cartridge all have shared environment variables in their scope ● Node Scope variables ● /etc/openshift/env ● Gear Scope ● .../<gear uuid>/.env ● Application Scope ● .../<gear uuid>/.env/<cartridge name> ● Cartridge Scope ● .../<gear uuid>/<cartridge name>/env
- 22. Example Platform Environment Variables ● OPENSHIFT_APP_NAME ● OPENSHIFT_APP_DNS ● OPENSHIFT_DATA_DIR ● OPENSHIFT_HOMEDIR ● OPENSHIFT_TMP_DIR ● OPENSHIFT_<SHORT NAME>_DIR ● OPENSHIFT_<SHORT NAME>_IP ● OPENSHIFT_<SHORT NAME>_PORT ● You and application developer use these to tie into the software you are packaging ● System tracks them and builds the correct process environment for you
- 23. Creating An Application With Your Cartridge ● rhc create-app dog001 http://…/metadata/manifest.yml ● Tip: use raw URL from github ● manifest.yml contains Source-Url element ● Source-Url addresses root of your cartridge ● Tip: use download zip file from github repository
- 24. Tip: Origin VM as a development platform ● http://openshift.github.io/ ● Broker-Node communication ● /var/log/mcollective.log ● Node logging ● /var/log/openshift/node/platform.log ● Node detailed logging ● /var/log/openshift/node/platform-trace.log ● Warning: Origin – Fedora 18 Online – RHEL 6
- 25. Tip: Examples – Online Cartridges ● http://tinyurl.com/online-cartridges ● JBoss EWS: multiple versions of packaged software and support for multiple java versions ● MySQL: pub/sub database connections ● PHP My Admin: one cartridge dependent on another
- 26. Tip: Using bash for scripts ● -e and -u options are your friends ● -e exit on error ● -u using unset variable is an error ● -x for debugging ● Bash “SDK” (Library of functions) ● source $OPENSHIFT_CARTRIDGE_SDK_BASH
- 27. ERB File Rendering ● Unified method of doing value substitutions in configuration files ● httpd.conf, php.ini, etc ● metadata/managed_files.yml ● processed_templates: - '**/*.erb' ● All environment variables available ● No code can be executed
- 28. Title here Text with no bullets ● Bullets layer one ● Bullets layer two ● Bullets layer three
- 29. Additional Resources! ● Cartridge Writing Guide: http://tinyurl.com/writing-cartridges ● IRC Freenode ● #openshift (application developers) ● #openshift-dev (PaaS development) ● #openshift-dev-node (cartridge/node development) ● Email ● dev@lists.openshift.redhat.com
- 30. For more information: http://openshift.github.io Follow us on twitter: @openshift Join us on irc (freenode): openshift