Pivotal Cloudfoundry makes the work of performing 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 instructor / space development as admin... 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 instructor / space development as admin... OK requested state: started instances: 3/3 usage: 512M x 3 instances urls: env-grumous-imperativeness.cfapps.haas-76.pez.pivotal.io last uploaded: Mon Oct 17 00:13:08 UTC 2016 stack: windows2012R2 buildpack: binary_buildpack state since cpu memory disk details #0 running 2016-10-16 08:37:52 PM 0.2% 113.4M of 512M 3.8M of 1G #1 starting 2016-10-16 08:53:26 PM 0.2% 110.2M of 512M 3.8M of 1G #2 starting 2016-10-16 08:53:26 PM 0.2% 111.6M of 512M 3.8M of 1G >-
This application instance has completed the startup process and is actually able to accept requests.
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This application instance is still starting and will not have any requests routed to it.
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Eventually all instances will converge to a running state:
> cf app env Showing health and status for app env in org instructor / space development as admin... OK requested state: started instances: 3/3 usage: 512M x 3 instances urls: env-grumous-imperativeness.cfapps.haas-76.pez.pivotal.io last uploaded: Mon Oct 17 00:13:08 UTC 2016 stack: windows2012R2 buildpack: binary_buildpack state since cpu memory disk details #0 running 2016-10-16 08:37:52 PM 0.2% 113.4M of 512M 3.8M of 1G #1 running 2016-10-16 08:52:16 PM 0.0% 110.1M of 512M 3.8M of 1G #2 running 2016-10-16 08:52:17 PM 0.0% 111.5M of 512M 3.8M of 1G -
Revisit the application route in the browser and select the CloudFoundry Config menu item. 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 therunningstate, 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 instructor / space development as admin... OK
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Check the application status again:
> cf app env Showing health and status for app env in org instructor / space development as admin... OK requested state: started instances: 1/1 usage: 512M x 1 instances urls: env-grumous-imperativeness.cfapps.haas-76.pez.pivotal.io last uploaded: Mon Oct 17 00:13:08 UTC 2016 stack: windows2012R2 buildpack: binary_buildpack state since cpu memory disk details #0 running 2016-10-16 08:37:52 PM 0.0% 113.8M of 512M 3.8M 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
Showing health and status for app env in org instructor / space development as admin...
OK
requested state: started
instances: 1/1
usage: 512M x 1 instances
urls: env-grumous-imperativeness.cfapps.haas-76.pez.pivotal.io
last uploaded: Mon Oct 17 00:13:08 UTC 2016
stack: windows2012R2
buildpack: binary_buildpack
state since cpu memory disk details
#0 running 2016-10-16 08:37:52 PM 0.2% 116.9M of 512M 3.8M of 1G
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 Unmap 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 detaild instructions.
