Lab - Strangle Your Monolith

Return to Workshop

Strangling the Monolith Design Pattern

Steps for Strangling the Monolith

1) Strangle Monolith

2) Add a Microservice

3) And Another

4) Squeeze Monolith

5) And Remove Dead

Step 1

  • First, build and deploy the catalog microservice (Based on Spring Boot)
$ cd ~/coolstore
$ git clone -b app-partner https://github.com/epe105/catalog
$ cd catalog

Please update <USERNAME> below with your assigned username

$ oc project coolstore-<USERNAME>
$ mvn clean fabric8:deploy -Popenshift -DskipTests

Step 2

Once the new catalog service is deployed, test it with curl:

$ oc get route/catalog
NAME      HOST/PORT                                              PATH      SERVICES   PORT      TERMINATION
catalog   catalog-coolstore-<USERNAME>.apps.ocp.naps-redhat.com            catalog    8080

Curl using the HOST/PORT from the previous step

$ curl http://catalog-coolstore--USERNAME>.apps.ocp.naps-redhat.com/api/catalog

[{"itemId":"329299","name":"Red Fedora","desc":"Official Red Hat Fedora","price":34.99},{"itemId":"329199","name":"Forge Laptop Sticker","desc":"JBoss Community Forge Project Sticker","price":8.5}
...

You can also test it by clicking on the route to the catalog service and adding /api/catalog to the URL:

Step 3

Now we will do the same for the Inventory service, based on WildFly Swarm:

$ cd ~/coolstore
$ git clone -b app-partner https://github.com/epe105/inventory
$ cd inventory

Please update <USERNAME> below with your assigned username

$ oc project coolstore-<USERNAME>
$ mvn clean fabric8:deploy -Popenshift  -DskipTests

Step 4

Get the POSTGRESQL_PASSWORD

$ oc env dc/inventory-database --list # get the POSTGRESQL_PASSWORD

Get the postgresql pod

$ oc get pods

oc rsh into the postgresql pod from the previous step

$ oc rsh inventory-database-1-kkxs2
sh-4.2$ psql -h $HOSTNAME -d $POSTGRESQL_DATABASE -U $POSTGRESQL_USER
Password for user userV31:XXXXXXXX
psql (9.5.4)
Type "help" for help.

monolith=> select * from inventory;
 itemid |               link                | location | quantity
--------+-----------------------------------+----------+----------
 329299 | http://maps.google.com/?q=Raleigh | Raleigh  |      736
...

Exit out of psql and then the postgresql pod

monolith=> \q
sh-4.2$ exit
exit

Step 5

Once the new service is deployed, test it with curl
You should get a JSON object representing the inventory availability of product 329299

$ oc get route/inventory
NAME        HOST/PORT                                                  PATH      SERVICES    PORT      TERMINATION
inventory   inventory-coolstore-<USERNAME>.apps.ocp.naps-redhat.com              inventory   8080
$ curl http://inventory-coolstore-<USERNAME>.apps.ocp.naps-redhat.com/api/inventory/329299
{"itemId":"329299","location":"Raleigh","quantity":736,"link":"http://maps.google.com/?q=Raleigh"}

You can also test it by clicking on the route to the inventory service and adding /api/inventory/329299 to the URL

Strangling Your Monolith Lab Architecture

Once the new Microservices are deployed, this is the Architecture of this Lab

Return to Workshop