What does canary in BOSH mean?

[res...@gmail.com]

Hi, all

I'm a little confused by the canary part of BOSH...So there're some basic questions.

I noticed when I updating jobs in BOSH, some vm are tagged as "canary". What does this mean? Means that vm will not connect to CF unless it pass all the tests? But how can u determine it is well enough, by spec files or status port?

[Dr Nic Williams]

When performing updates, bosh does things in batches. The number of VMs in each batch is determined by the "update:" section of the deployment file.

The first batch is called the canary. It allows you to specify a small number of VMs in the first batch to change.

If the canary batch fail to upgrade then the deployment/change is halted. Your remaining VMs are unaffected; and your canary VMs are left as they are - probably broken in some way - ready for you to diagnose and fix.

--
Dr Nic Williams
Stark & Wayne LLC - the consultancy for Cloud Foundry
http://starkandwayne.com
+1 415 860 2185
twitter: drnic