| # Why you should use the system ready project |
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| ## Error reporting and root cause analysis |
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| When a system fails to become ready after a certain amount of time, the follow up question is : "What is wrong?". So the framework also provides a way for each system check to report back information about errors. |
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| One typical error is that a DS component does not come up because some mandatory dependency is not present. This dependency can be a configuration or maybe a service reference. In many cases, a trivial error like a missing configuration for a low level component can cause a lot of other components to fail to register. The root cause analysis allows traversing the trees of components and to narrow the reason for the system not being ready to a minimal number of possible causes for the failure state. |
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| ## Use cases |
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| Typical use cases for the system ready check ordered by the phase of the development cycle. |
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| ### Development |
| * Coarse check of a pax exam based setup before letting the actual junit tests work on the system |
| * Determining the root cause of a pax exam based setup not starting |
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| ### QA |
| * Starting system tests as soon as a system is ready for the tests to proceed |
| * Determining the root cause for an OSGi based system not starting up |
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| ### Deployment |
| * Signaling when a system is ready after an upgrade so that it can receive traffic in the case of blue / green deployments |
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| ### Production |
| * Periodic _Ready health checks_ for system and signaling this state to monitoring systems |
| * Container automation and driving _autopilot container_ deployments. |
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| ## Added value when using the system ready framework |
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| * Increased deployment resilience as deployments are checked before being exposed |
| * Faster deployments / upgrades by replacing fixed, error-prone waits with ready based waits |
| * Lower bug tracking efforts in tests as root causes are easier to find |
| * Configurability of _when_ a certain deployment is considered ready (e.g. after content sync with an external service) |
