CODEWITHSUNDEEP
cloud-foundry
Dakota Brown
Dakota Brown

Reputation: 750

CloudFoundry Instance Environment Variable?

I have a Java web app that persists some things to a database and I would like to know what instance processed the order. A quick google and SO search wasn't fruitful in answering my question:

Is there an environment variable or something that my application can use to glean an instance number from for persisting?

Upvotes: 0

Views: 6299

Answers (2)

TK8
TK8

Reputation: 135

From the logs, you can see the APP instance

2015-11-13T11:44:42.000+00:00 [App/0] OUT 11:44:42.675 [main] INFO blah blah
2015-11-13T11:45:42.000+00:00 [App/1] OUT 11:45:42.676 [main] INFO blah2

here App/0 is instance 0 & App/1 is instance 1.

Or if you want to access the instance in the code,

Look out for the env var, CF_INSTANCE_*

eg; CF_INSTANCE_INDEX, CF_INSTANCE_IP, CF_INSTANCE_PORT etc

Upvotes: 1

Amit Kumar Gupta
Amit Kumar Gupta

Reputation: 18567

I assume that by "what instance" you mean that you have multiple instances of your Java application, and you want some way of knowing which of the multiple instances actually made the request to the database.

Googling "Cloud Foundry Instance Environment Variable" leads me to this first result. You can see one of the listed variables is CF_INSTANCE_INDEX. Those docs are for Pivotal's hosted Cloud Foundry service, I guess the OSS docs have worse SEO, but they also document this.

Do note that application instances are ephemeral. Instance #0 might be killed and restarted for any number of reasons (usually either because your application crashes, or the underlying application execution software/OS are being upgraded in a rolling deploy fashion so your instances are being transparently moved around to avoid downtime), in which case the new instance #0 will obviously be an entirely different process, possibly running on a different machine, in a different datacenter.

Upvotes: 1

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