Small demo-setup for a container-based Navajo instance

This setup will start three containers:

• A postgres database with some fake movie data
• An empty mongodb instance
• A navajo container pointing to the two databases

The Navajo container has a few scripts that implement webservices to access the data in the databases.

Using this demo

To use this demo, clone this repository:

%> git clone https://github.com/Dexels/navajo-demo.git

This will clone a simple navajo project along with some docker configuration files. It uses docker-compose, a simple piece of configuration that allows us to start multiple docker containers at once:

The docker compose file looks as follows:

version: '3'
services:

  postgres:
    image: dexels/dvdrental:1.0.7
    ports:
      - "5432:5432"
    environment:
      POSTGRES_PASSWORD: mysecretpassword

  mongodemo:
    image: mongo:latest
    ports:
      - "27017:27017"

  navajo:
    image: dexels/navajo-demo:1
    ports:
      - "8181:8181"
    environment:
     - CLUSTER=demo
     - HAZELCAST_SIMPLE=true
     - FILE_REPOSITORY_DEPLOYMENT=develop

It defines three containers, called "mongodemo", "postgres", and "navajo". The mongodemo container exposes the standard mongodb port at 27017, the postgres container the standard postgres port at 5432, and navajo container exposes an HTTP port at 8181.

The docker compoose command

%> docker-compose up

starts all three containers, and after a while they should all be up and running. You can then use a navajo tester webpage in a browser, using the following URL.

http://localhost:8181/tester.html

When prompted use:

• Username: admin
• Password: admin

Now you can call Navajo scripts by clicking on the script tree on the left. For example, open "movie/ActorList". That will open a script that queries a list of fake films.

Entities are special kind of webservice provided by navajo that can be accessed using a REST interface. Entities can be examined at

http://localhost:8181/entityDocumentation/movie

using a separate tester webpage.

Additionally, you can inspect the navajo system using OSGi web console. The web console can be found at

http://localhost:8181/system/console/bundles

This web endpoint gives deep insight in the state of the system, it can be an invaluable tool to troubleshoot the system. For example, the 'bundles' tab shows all active OSGi bundles (An OSGi bundle is essentially a jar file with some extra metadata). An OSGi bundle specifies precisely what java packages it publishes to other bundles and which packages it needs from other bundles. This adds some complexity to building those bundles, as the dependencies between bundles have to be specific and precise. This can be very helpful though, as the OSGi framework will try to resolve all those dependencies when starting up (or when the system changes at runtime), and can precisely tell you when there is a problem, before you get a runtime error. Effectively that means that you can check the bundles tab to see if there are bundles that could not be resolved, typically those show up as bundles that do not have the state 'Active' or 'Fragment'. If a bundle is unresolved, it also won't publish it's own package, so generally when there is one unresolved bundle, all bundles depending on that bundle will also be unresolved. You can use this interface to figure out what the root-cause is of this class path issue.

For more in-depth information on how to use the OSGi web console I refer to the Felix project:

https://felix.apache.org/documentation/subprojects/apache-felix-web-console.html

Statistics on the invocations of the webservices can be found at a monitoring webpage at

http://localhost:8181/Monitor/index.html

Shutting down

%> docker-compose down

(You can check with cluster are running using 'docker-compose ps', or check 'docker ps' for individual containers)

Connecting to the MongoDB database

Open a connection to localhost:27017 using your favorite mongodb access tool (e.g., MongoDB Compass or Robo 3T).

Connecting to the Postgres database

Open a connection to localhost:5432 using your favorite database access tool (e.g., DbVisualizer)

Username: postgres

Password: mysecretpassword

Editing / rebuilding

Try editing / adding scripts in navajo/scripts. Then rebuild:

%> docker-compose build

And bring it back up:

%> docker-compose up

For more about docker / docker-compose, there is very nice documentation available at https://docs.docker.com/get-started/