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tutorial_01_03_mongodb
In this tutorial we will see how to save data that is created via the OData calls to our n-odata-server application
into a MongoDB database.
The YaaS CF (Cloud Foundry) platform not only offers a runtime platform for Java and node.js applications
but it also provides some services that can be used in custom applications easily.
One of these services is a MongoDB service that exposes a MongoDB to the applications.
In this tutorial you will see how easy it is to use such a service. You don't have to install a
database, care about all that network stuff, ... You simply create a service instance for your organisation and
bind you app to this service. It's a matter of minutes and you're able to save data to a
database with CF (YaaS).
The source code of this tutorial can be found on github. For each step we
create a new branch. The master branch always contains the last evolution of this tutorial. The source code of this tutorial
is available in branch 03_mongodb.
Check out this branch if you don't want to do all the typing yourself.
If you want to follow this tutorial on you own you should have already followed the first two tutorials in this series. You can find them here:
And as mentioned in the last tutorial you need an account on SAP Hana Cloud Platform as well as on SAPs microservice platform YaaS. Both platforms can be used for development and test purposes free of charge.
We do some of the work of this tutorial via the CLI of the YaaS CF platform. Hence you should have installed the CF CLI tools.
See the last tutorial for a link to the YaaS installation guide.
The CF command are executed in a terminal (command line) window. So you have to open one now.
First we have to login.
If you have more than one CF provider you firstly have to select the YaaS provider via the following command
cf api https://api.cf.us10.hana.ondemand.com
Then you can login via
cf login
Email> <enter your YaaS email address>
Password> <enter your YaaS password>
After you have been authenticated you get some information about your connection that looks like this
API endpoint: https://api.cf.us10.hana.ondemand.com (API version: 2.59.0)
User: <your YaaS email address>
Org: <your CF organisation>
Space: dev
As we want to save our data into a MongoDB database we have to subscribe to the MongoDB service. This service is provided by SAP in the free YaaS account free of charge. To see which services are provided and how the MongoDB service is named we have a look at the CF marketplace.
cf marketplace
The result should look like this
service plans description
mongodb v3.0-container MongoDB document-oriented database system
postgresql v9.4-container PostgreSQL object-relational database system
rabbitmq v3.6-container RabbitMQ messaging
redis v3.0-container Redis in-memory data structure store
To create a service instance that we can use in our organisation we have to run the following command
cf create-service mongodb v3.0-container mongodb-service
create-service is the CF command
mongodb is the service we want to use (see list above)
v3.0-container is the plan that in a productive environment is used for several payment options
mongodb-service is the name we give the service instance in our landscape. You can name it as you want but have to
remember it cause we use it later on.
As soon as you got an OK from CF you can check if the service instance has been created.
cf services
Here is the result (tadaa)
name service plan bound apps last operation
mongodb-service mongodb v3.0-container create succeeded
As you can see currently no app is bound to that service instance. To be able to use it in our tutorial app. We can use
the bind-service command. This command needs to know the name of the app and the name of the service. If you
forgot the name of your app run
cf apps
You get the list of apps running in your organisation resp. space
name requested state instances memory disk urls
n-odata-server-tut-01 started 1/1 256M 512M n-odata-server-tut-01.cfapps.us10.hana.ondemand.com
Now as we know the name of our app (n-odata-server-tut-01) and the name of our service instance (mongodb-service) we
run the command
cf bind-service n-odata-server-tut-01 mongodb-service
CF returns with an OK and with a TIP which we follow
OK
TIP: Use 'cf restage n-odata-server-tut-01' to ensure your env variable changes take effect
cf restage n-odata-server-tut-01
This command restages the complete application which means it builds it completely new like after a cf push. At the
end it should tell you that the application is running
state since cpu memory disk details
#0 running 2016-10-20 06:43:13 PM 91.0% 229M of 256M 186.3M of 512M
To check if the service is really bound to the app enter
cf env n-odata-server-tut-01
This will display the environment variables of the app and the bound services. We will need some of this information later.
System-Provided:
{
"VCAP_SERVICES": {
"mongodb": [
{
"credentials": {
"dbname": "6kjcovkykhddgtnv",
"hostname": "10.11.241.3",
"password": "****************",
"port": "36031",
"ports": {
"27017/tcp": "36031",
"28017/tcp": "47609"
},
"uri": "mongodb://fpa5n50e1dcwpdas:****************@10.11.241.3:36031/6kjcovkykhddgtnv",
"username": "fpa5n50e1dcwpdas"
},
"label": "mongodb",
"name": "mongodb-service",
"plan": "v3.0-container",
"provider": null,
"syslog_drain_url": null,
"tags": [
"mongodb",
"document"
],
"volume_mounts": []
}
]
}
}
{
"VCAP_APPLICATION": {
"application_id": "d051adff-4594-4ff7-8fe6-d5893fae75ea",
"application_name": "n-odata-server-tut-01",
"application_uris": [
"n-odata-server-tut-01.cfapps.us10.hana.ondemand.com"
],
"application_version": "a94b501b-9fbd-4df3-926e-802656d1de13",
"limits": {
"disk": 512,
"fds": 16384,
"mem": 256
},
"name": "n-odata-server-tut-01",
"space_id": "e6708a35-3b68-4288-98f9-c82e35800af5",
"space_name": "dev",
"uris": [
"n-odata-server-tut-01.cfapps.us10.hana.ondemand.com"
],
"users": null,
"version": "a94b501b-9fbd-4df3-926e-802656d1de13"
}
}
No user-defined env variables have been set
No running env variables have been set
No staging env variables have been set
Now that we have prepared the CF environment we need to do some adjustments to our application.
Currently we use an in-memory datasource with local file storage to store the data of our application.
To store the data to the MongoDB database we have to create an according datasource.
This can be easily done with the slc command line tool.
slc loopback:datasource
Fill in the questions. Copy the data from the mongodb environment variables (see above, the **** are a placeholder for the password)
? Enter the data-source name: mongodb
? Select the connector for mongodb: MongoDB (supported by StrongLoop)
Connector-specific configuration:
? Connection String url to override other settings (eg: mongodb://username:password@hostname:port/database): mongodb://fpa5n50e1dcwpdas
:****************@10.11.241.3:36031/6kjcovkykhddgtnv
? host: 10.11.241.3
? port: 36031
? user: fpa5n50e1dcwpdas
? password: ****************
? database: 6kjcovkykhddgtnv
? Install loopback-connector-mongodb@^1.4 Yes
Answer the last question with Yes. This will automatically install the mongodb database driver (connector)
for loopback. When you ran this command there is an additional dependency to the loopback-connector-mongodb
in the package.json file and you see a new datasource in the file server/datasource.json
"mongodb": {
"host": "10.11.241.3",
"port": 36031,
"url": "mongodb://fpa5n50e1dcwpdas:****************@10.11.241.3:36031/6kjcovkykhddgtnv",
"database": "6kjcovkykhddgtnv",
"password": "****************",
"name": "mongodb",
"user": "fpa5n50e1dcwpdas",
"connector": "mongodb"
}
The next step is to change the datasource of all created models from db to mongodb. To achieve this you have to
edit the file server/model-config.json and change the datasource of all models which data you want to be saved in
the MongdDB database. Here is an example
"person": {
"dataSource": "mongodb",
"public": true
}
A nice thing about loopback is that you can uses several datasources in parallel.
Last step is to adjust the manifest.yml file. You have to add the mongodb-service. The file should look like this
(notice the new services section at the end)
applications:
- path: .
memory: 256M
disk_quota: 512M
instances: 1
domain: cfapps.us10.hana.ondemand.com
name: n-odata-server-tut-01
host: n-odata-server-tut-01
buildpack: nodejs_buildpack
services:
- mongodb-service
We are finished and so can push our new app to YaaS aka CF.
cf push
After some time you get this result. Your application is running. Wow !!!!
state since cpu memory disk details
#0 running 2016-10-20 10:48:26 PM 0.0% 242.5M of 256M 209M of 512M
The usage of the application doesn't change. It's the same as before. The only difference is that the results contain another id. This
is generated by MongoDB and doesn't start with 1.
To make your life easier the requests for inserting and retrieving person object are listed below. For the other requests
have a look at tutorial_01_02_yaas
curl -X POST -H "Content-Type: application/json" -d '{
"firstname": "Helmut",
"lastname": "Tammen"
}' "https://<your hostname>.cfapps.us10.hana.ondemand.com/odata/people"
Result:
{
"d": {
"firstname": "Helmut",
"id": "58092f1589e6de2b00b7ea1a",
"lastname": "Tammen"
}
}
curl -X GET -H "Accept: Accept: application/json" -H "Content-Type: application/json" "https://n-odata-server-tut-01.cfapps.us10.hana.ondemand.com/odata/people"
Result:
{
"d": {
"results": [
{
"__metadata": {
"type": "NODATASERVER.person",
"uri": "http://<your hostname>.cfapps.us10.hana.ondemand.com:61694/odata/people(1)"
},
"firstname": "Helmut",
"id": "58092f1589e6de2b00b7ea1a",
"lastname": "Tammen"
}
]
}
}
If you stop or restart your application via cf stop or cf restart the data you saved will not be lost anymore.
This is because the data is not saved in a local file anymore but in an external database.
Now we can savely change and redeploy our app without deleting data each time.
You don't believe that the data is saved in an external database?
Unfortunately YaaS doesn't offer a database management tool. But you can have a look at the local file storage/data.json to see that your
new records are not saved there as before. Just run the command
cf files n-odata-server-tut-01 app/storage/data.json
This command outputs the content of the file to the console. It's content is either empty or the same as the file on your local PC (cf push pushed the file to the server). If you add new data to your OData service this will not appear in this file.
Another interesting command is
cf service mongodb-service
This displays information about your service instance. It contains amongst others a link to a Dashboard. Enter this URL in your browser to get more information about the service. You can also see the logs of the database there.
Stay tuned