SpringOne2GX 2015 - Going Cloud Native (locally) with Lattice

24 September 2015 // Ola Deibitsch

During SpringOne2GX I listened to Matt Stine´s presentation about Lattice, a stripped-down version of Cloud Foundry which really lowers the barrier to get started to develop and test cloud-native architectures…

…literally speaking, Lattice enables a kickstart for developers to install micro-cloud environments on the their local desktops. Lattice reduces the overall footprint from an infrastructure perspective and allows to get started in just minutes.

Lattice Architecture

Behind the scenes, we recognize the following components from Cloud Foundry:

• Router is responsible for load balancing traffic across running containers which can be updated dynamically as applications are launched or spun down.
• Diego the Cloud Foundry’s upcoming elastic runtime for containers. Diego is responsible for scheduling and running containerized workloads.
• Doppler/Loggregator is responsible for streaming logs out of running containers.

Lattice consists of:

• Cluster Scheduling
• Load Balancing (HA Proxy)
• Health Management
• Log Aggregation

Installation

Lattice is installed easiest by using Vagrant (Mac OS X):

$ curl https://lattice.s3.amazonaws.com/nightly/lattice-bundle-v0.4.3-osx.zip
$ unzip lattice-bundle-v0.4.3-osx
$ cd lattice-bundle-v0.4.3-osx/vagrant
  
$ vagrant up

Within minutes, a Lattice VM will be reachable at 192.168.11.11.

To be able to interact with Diego, Lattice offers a CLI, also refered to as ltc, that help to manage the Garden containers.

The Lattice CLI is a downloaded as a part of the “lattice-bundle” and in order to connect to the Lattice VM, we are using the ltc:

$ cd lattice-bundle-v0.4.3-osx
$ ltc target 192.168.11.11.xip.io

To lists applications and tasks running on Lattice:

$ ltc list

Deployment

Lattice makes deployment of applications very simple and straightforward. The following demo will utilize Spring Cloud Config to provide server and client support for externalized configuration.

In order to show different deployment options with Lattice, I let the server (refered as “config server”) to be deployad as a docker container given an existing image from Docker Hub. A simple client (refered as “config client”) will be deployed as a minimal Spring Boot application into a droplet container.

The client application also supports updating the properties dynamically. This is by adding a @RefreshScope annotation and a dependency to the Spring Boot Actuator.

Deployment of a Docker Image

Now, the next step is to install the config-server from a Docker Hub:

$ ltc create config-server springcloud/configserver --run-as-root --memory-mb 256 --env spring.cloud.config.server.git.uri=https://github.com/deibitsch/config-repo

Verify that the config-server application is up and running on Lattice:

$ ltc status config-server

Deployment of a Droplet

This shows how to clone, build and deploy a minimal Spring Boot application into a Dropet.

$ cd ~/Documents/Development/git-repos
$ git clone https://github.com/deibitsch/config-client.git
$ cd config-client
$ mvn clean install

Build config-client into a droplet using a CF buildpack:

$ ltc build-droplet config-client java -p ~/Documents/Development/git-repos/config-client/target/config-client-0.0.1-SNAPSHOT.jar --env spring.cloud.config.uri=http://config-server.192.168.11.11.xip.io

List existing droplets:

$ ltc list-droplets

Launch a the droplet as an app running on Lattice by:

$ ltc launch-droplet config-client config-client

Verify the config-client app on Lattice:

$ ltc status config-client

The client application has two endpoints:

• / returns greeting message (“HELLO LATTICE”)
• /refresh enables to refresh properties from central repository (git backend) using “config-server”.

You should be able to visit http://config-client.192.168.11.11.xip.io in your browser.

$ open http://config-client.192.168.11.11.xip.io

The property greeting.message can now be dynamically updated by applying a new value to config-client.properties in central git-repo. The invocation (HTTP POST) of the /refresh endpoint will update property due to @RefreshScope annotation in the config-client application.

$ curl -X POST http://config-client.192.168.11.11.xip.io/refresh

The updated property should be updated if you refresh http://config-client.192.168.11.11.xip.io in your browser.

$ open http://config-client.192.168.11.11.xip.io

Logging

The Lattice CLI enables to stream logs from a specific application:

$ ltc logs config-client

Simply, invoke the “/refresh” endpoint resulting in log messages to be visible in the terminal:

$ curl -X POST http://config-client.192.168.11.11.xip.io/refresh

Scaling

In order to scale up the number of instances of the client application:

$ ltc scale config-client 2

Verify that there are two instances running:

$ ltc status config-client