Pivotal Cloudfoundry makes the work of performing operations actions, such as scaling, doing a zero-downtime deploy, and managing application health very easy. In the next two labs we’ll explore Pivotal Cloud Foundry operations.
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Now let’s increase the number of running application instances to 3. :
> cf scale env -i 3 Scaling app env in org student-42 / space development as student-42... OK
In reporting
OK, the CLI is letting you know that the additional requested instances have been started, but they are not yet necessarily running. -
We can determine how many instances are actually running like this:
> cf app env Showing health and status for app env in org student-42 / space development as student-42... OK requested state: started instances: 3/3 usage: 512M x 3 instances urls: env-farraginous-thunderclap.apps.pcf4u.com last uploaded: Sun Feb 19 18:18:32 UTC 2017 stack: windows2012R2 buildpack: binary_buildpack state since cpu memory disk details #0 running 2017-02-19 01:23:28 PM 0.0% 0 of 512M 0 of 1G #1 running 2017-02-19 01:25:52 PM 0.0% 0 of 512M 0 of 1G #2 running 2017-02-19 01:25:53 PM 0.0% 0 of 512M 0 of 1G > -
Revisit the application route in the browser. Refresh several times. You should observe the instance index changing as you do so:
The aforementioned (Go)Router is applying a random routing algorithm to all of the application instances assigned to this route. As an instance reaches the
runningstate, its Diego Cell registers that instance in the routing table assigned to its route by sending a message to Cloud Foundry’s message bus. All (Go)Router instances are subscribed to this channel and register the routes independently. This makes for very dynamic and rapid reconfiguration!
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We can scale the application instances back down as easily as we scaled them up, using the same command structure:
> cf scale env -i 1 Scaling app env in org student-42 / space development as student-42... OK
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Check the application status again:
> cf app env Showing health and status for app env in org student-42 / space development as student-42... OK requested state: started instances: 1/1 usage: 512M x 1 instances urls: env-farraginous-thunderclap.apps.pcf4u.com last uploaded: Sun Feb 19 18:18:32 UTC 2017 stack: windows2012R2 buildpack: binary_buildpack state since cpu memory disk details #0 running 2017-02-19 01:23:28 PM 0.0% 0 of 512M 0 of 1GAs you can see, we’re back down to only one instance running, and it is in fact the original index 0 that we started with.
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Confirm that by again revisiting the route in the browser and checking the instance index:
There are two ways to discover what routes, or HTTP URLs, are ampped to an application The first is available via the CLI. Just type:
> cf app env
and you’ll see the list of routes in the section that says urls.
The second way is via the Apps Manager UI. Click on the env application to view application details. Select the Routes tab to view a list of mapped routes:
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We can easily add an additional route by clicking on + Map a Route and supplying the new hostname:
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Navigate to the new URL in your browser window. You should see that same application displayed!
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We can just as easily remove a route by clicking on x icon on the route you wish to remove.
If you navigate to that URL you’ll receive a HTTP 404 response
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This is how blue-green deployments are accomplished. Check the documentation for detailed instructions.
