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Blue-green deployment is a technique that reduces downtime and risk by running two identical production environments called Blue and Green.
At any time, only one of the environments is live, with the live environment serving all production traffic. For this example, Blue is currently live and Green is idle.
As you prepare a new version of your software, deployment and the final stage of testing takes place in the environment that is not live: in this example, Green. Once you have deployed and fully tested the software in Green, you switch the router so all incoming requests now go to Green instead of Blue. Green is now live, and Blue is idle.
This technique can eliminate downtime due to app deployment. In addition, blue-green deployment reduces risk: if something unexpected happens with your new version on Green, you can immediately roll back to the last version by switching back to Blue.
The example will demonstrate how to acomplish blue-green deployment using MTA.
MTA blue-green deployment is separeted in two phases.
First phase, so called validation is phase setup the next color environment, in order to be tested. The new environment version, in this case GREEN, is not accessible on the production routes but on temporary -idle routes. The validation phase is used to verify that new version of environment is operational.
During second phase all new applications are assigned to production routes and the new MTA color become productive.
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Awarenes of blue green deploy in Cloud Foundry: Using Blue-Green Deployment to Reduce Downtime and Risk
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SAP Help Portal: Legacy Blue-Green Deployment
The example will demonstrate blue-green deployment of one MTA comprised of two applications. The first applcation, called "hello-backend", serves as backend and the second one, called "hello-router", serves as front end.
The idea is to have sample MTA which seems very similar to standard business applications that are comprised of frontend, backend and backing services. In the example "hello-backend" will play the combined role between backend and backing services, where the customer data is stored.
In terms of the example, we are using Java applications which communicate using REST interface. Both applications are simple web projects containing only one servlet.
| Application Color | hello-router | hello-backend |
|---|---|---|
blue |
GET /router → calls <hello-backend>/backend |
GET /backend → returns BLUE |
green |
GET /router → calls <hello-backend>/backend |
GET /backend → returns GREEN |
Initial blue green deployment is very similar to standard deployment because there are not existing applications. One difference is that temporary routes will be added during the deployment. Finally, the standard routes are assigned to the applications.
In the end of this part, you wil have similar environment:
You can try 3 different approaches, that will lead to the same result and the same output during the deployment. The differences are how the deploymnet is trigger.
$ cf bg-deploy hello-blue/hello.mtar -f
...
No deployed MTA detected - this is initial deployment
New MTA color: BLUE
...
Starting application "hello-backend-blue"...
Application "hello-backend-blue" started and available at "<org>-<space>-hello-backend-idle.cfapps.sap.hana.ondemand.com"
...
Starting application "hello-router-blue"...
Application "hello-router-blue" started and available at "<org>-<space>-i076083-2-hello-router-idle.cfapps.sap.hana.ondemand.com"
...
Application "hello-backend-blue" started and available at "<org>-<space>-hello-backend.cfapps.sap.hana.ondemand.com"
...
Application "hello-router-blue" started and available at "<org>-<space>-hello-router.cfapps.sap.hana.ondemand.com"The approach will use deployment descriptor hello-blue/mtad.yaml and already built application bineries hello-blue/router.war and hello-blue/backend.war
$ cf bg-deploy hello-blue/ -fThe approach will use development descriptor hello-blue/mta.yaml to build bineries from source code folders hello-blue/router/ and hello-blue/backend/. Then builded MTAR will be deployed.
|
Note
|
The Cloud MTA Build Tool is usiing maven to build Java applications by default. |
$ mbt build -p cf -s hello-blue
...
INFO validating the MTA project
INFO building the "hello-router" module...
INFO executing the "mvn -B package" command..
...
INFO the build results of the "hello-router" module will be packed and saved in the "/mta_examples/blue-green-deploy/hello-blue/.hello-blue_mta_build_tmp/hello-router" folder
INFO building the "hello-backend" module...
INFO executing the "mvn -B package" command...
...
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.301 s
[INFO] Finished at: xxxx
[INFO] ------------------------------------------------------------------------
INFO the build results of the "hello-backend" module will be packed and saved in the "/mta_examples/blue-green-deploy/hello-blue/.hello-blue_mta_build_tmp/hello-backend" folder
INFO generating the metadata...
INFO generating the MTA archive...
INFO the MTA archive generated at: /mta_examples/blue-green-deploy/hello-blue/mta_archives/hello_0.1.0.mtar
$ cf bg-deploy hello-blue/mta_archives/hello_0.1.0.mtarIn the end of this part, you wil have similar environment:
You can try 3 different approaches, that will lead to the same result
$ cf bg-deploy hello-green/hello.mtar -f
...
Deployed MTA color: BLUE
New MTA color: GREEN
...
Starting application "hello-backend-green"...
Application "hello-backend-green" started and available at "<org>-<space>-hello-backend-idle.cfapps.sap.hana.ondemand.com"
...
Starting application "hello-router-green"...
Application "hello-router-green" started and available at "<org>-<space>-hello-router-idle.cfapps.sap.hana.ondemand.com"
Process has entered validation phase. After testing your new deployment you can resume or abort the process.
Use "cf bg-deploy -i xxxx -a abort" to abort the process.
Use "cf bg-deploy -i xxxx -a resume" to resume the process.
Hint: Use the '--no-confirm' option of the bg-deploy command to skip this phase.The approach will use deployment descriptor hello-green/mtad.yaml and already built application bineries hello-green/router.war and hello-green/backend.war
$ cf bg-deploy hello-green/ -fVerify that both application version are now available
$ cf a
Getting apps in org xxx / space xxx as xxx...
OK
name requested state instances memory disk urls
hello-router-blue started 1/1 512M 256M <org>-<space>-hello-router.cfapps.sap.hana.ondemand.com
hello-backend-green started 1/1 512M 256M <org>-<space>-hello-backend-idle.cfapps.sap.hana.ondemand.com
hello-router-green started 1/1 512M 256M <org>-<space>-hello-router-idle.cfapps.sap.hana.ondemand.com
hello-backend-blue started 1/1 512M 256M <org>-<space>-hello-backend.cfapps.sap.hana.ondemand.comVerify that BLUE environment is still the productive one:
$ curl https://<org>-<space>-hello-router.cfapps.sap.hana.ondemand.com/router
BLUEVerify that GREEN environment can be accessed and validated on temporary -idle routes:
$ curl https://<org>-<space>-hello-router-idle.cfapps.sap.hana.ondemand.com/router
GREEN|
Note
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In case of a problem, the bg-deploy can be aborted without influencing the production environment. To stop the process copy-paste the suggested command by MTA CF CLI plugin: cf bg-deploy -i xxxx -a abort
|
At some point of time, you wil have similar environment, where both BLUE and GREEN applications are mapped to production routes.
In the end of this part, you wil have similar environment:
$ cf bg-deploy -i 1b59ca36-007e-11ea-bbed-eeee0a9e6b19 -a resume
Executing action 'resume' on operation xxxx...
...
Updating application "hello-backend-green"...
Stopping application "hello-backend-green"...
Starting application "hello-backend-green"...
Application "hello-backend-green" started and available at "<org>-<space>-hello-backend.cfapps.sap.hana.ondemand.com"
Publishing publicly provided dependency "hello:backend"...
Publishing publicly provided dependency "hello:hello-backend"...
Deleting discontinued configuration entries for application "hello-backend-green"...
Updating application "hello-router-green"...
Stopping application "hello-router-green"...
Starting application "hello-router-green"...
Application "hello-router-green" started and available at "<org>-<space>-hello-router.cfapps.sap.hana.ondemand.com"
Publishing publicly provided dependency "hello:hello-router"...
Deleting discontinued configuration entries for application "hello-router-green"...
Deleting routes for application "hello-router-blue"...
Deleting routes for application "hello-backend-blue"...
Stopping application "hello-router-blue"...
Deleting application "hello-router-blue"...
Stopping application "hello-backend-blue"...
Deleting application "hello-backend-blue"...
Process finished.Verify that old BLUE applications are deleted and new GREEN applications are assigned to production routes:
$ cf a
Getting apps in org xxx / space xxx as xxx...
OK
name requested state instances memory disk urls
hello-backend-green started 1/1 512M 256M <org>-<space>-hello-backend.cfapps.sap.hana.ondemand.com
hello-router-green started 1/1 512M 256M <org>-<space>-hello-router.cfapps.sap.hana.ondemand.comVerify that GREEN environent is the production one and serves on the production routes:
$ curl https://<org>-<space>-hello-router.cfapps.sap.hana.ondemand.com/router
GREENThere is an option to run end-to-end blue-green deployment without user interaction. The option is useful for CI and CD, where one MTA is continuously re-deployed without downtime.
In the end of this part, you wil have similar environment:
$ cf bg-deploy hello-blue -f --no-confirm
...
Deployed MTA color: GREEN
New MTA color: BLUE
...
Starting application "hello-backend-blue"...
Application "hello-backend-blue" started and available at "deploy-service-i076083-2-hello-backend-idle.cfapps.sap.hana.ondemand.com"
...
Starting application "hello-router-blue"...
Application "hello-router-blue" started and available at "deploy-service-i076083-2-hello-router-idle.cfapps.sap.hana.ondemand.com"
...
Application "hello-backend-blue" started and available at "deploy-service-i076083-2-hello-backend.cfapps.sap.hana.ondemand.com"
...
Starting application "hello-router-blue"...
Application "hello-router-blue" started and available at "deploy-service-i076083-2-hello-router.cfapps.sap.hana.ondemand.com"
...
Process finished.
Use "cf dmol -i xxx" to download the logs of the process.Verify that old GREEN applications are deleted and new BLUE applications are assigned to production routes:
$ cf a
Getting apps in org xxx / space xxx as xxx...
OK
name requested state instances memory disk urls
hello-backend-blue started 1/1 512M 256M <org>-<space>-hello-backend.cfapps.sap.hana.ondemand.com
hello-router-blue started 1/1 512M 256M <org>-<space>-hello-router.cfapps.sap.hana.ondemand.comVerify that BLUE environent is the production one and serves on the production routes:
$ curl https://<org>-<space>-hello-router.cfapps.sap.hana.ondemand.com/router
BLUE