containers/

README

imgn containerized

The overall architecture of imgn as a containerized microservices app looks as follows:

There are two deployments and a service defined in app.yaml and a Minio deployment and service (the S3 clone) in storage.yaml:

• The frontend deployment using container image quay.io/mhausenblas/imgn-frontend:0.3:0.3, along with the respective frontend service which serves static assets (the UI) via / and exposes the HTTP API endpoints:
  • /upload … handling multipart/form-data POST requests to upload an image
  • /gallery … handling GET requests by querying the imgn-gallery bucket hosted by Minio and returning a JSON encoded list of images and metadata
• The imgproc deployment using container image quay.io/mhausenblas/imgn-imgproc:0.3 which periodical checks for new images in the imgn-gallery bucket and if it finds a new one, it extracts metadata and writes it back into the bucket.
• The minio deployment using container image quay.io/mhausenblas/minio:1 along with the respective minio service, providing S3 storage and retrieval functionality.

Preparation

Make sure you have Kubernetes in version 1.8 or above available (check with kubectl version --short). You can, for example, use the Katacoda playground for this. I'll be using OpenShift Online in the following.

First, create a namespace for the imgn. This is the place all imgn components will be deployed to:

$ kubectl create ns imgn

Since I'm using OpenShift, rather than creating a namespace using above command, I'm creating a project (think of it as a namespace on steroids) via the oc new-project imgn command.

Next, clone this repository here using the following command; this makes all manifest files we're using for the deployment available:

$ git clone https://github.com/mhausenblas/imgn.git
$ cd imgn/containers

Deploy

To deploy the entire imgn app, simply do the following:

$ kubectl -n=imgn apply -f storage.yaml
$ kubectl -n=imgn apply -f app.yaml

Wait for a few minutes, giving Kubernetes time to pull the container images and when you see something like the following (all pods should have the status Running) you know everything is fine:

$ kubectl -n=imgn get pod,svc,deploy
NAME                        READY     STATUS    RESTARTS   AGE
frontend-6b7b596bd4-2qkns   1/1       Running   0          5m
imgproc-bcb7dcc5f-7xwkc     1/1       Running   0          5m
minio-74b998f6bc-cfncm      1/1       Running   0          5m

NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
frontend     ClusterIP   10.100.190.215   <none>        80/TCP     5m
kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP    12m
minio        ClusterIP   10.107.25.237    <none>        9000/TCP   5m

NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
frontend   1         1         1            1           5m
imgproc    1         1         1            1           5m
minio      1         1         1            1           5m

Use

Now that imgn is deployed, in order to use it, it depends on the environment what options you have to make the frontend available to clients outside of the cluster.

All cloud providers provide load balancers you can use, you could set up your own Ingress controller and expose the service via an Ingress resource, or, if you're using OpenShift as I do here, you can simply benefit from the built-in Routes feature, allowing you to make the frontend available like so:

$ oc expose svc frontend
$ oc describe route frontend
Name:                   frontend
Namespace:              imgn
Created:                26 seconds ago
Labels:                 app=frontend
Annotations:            openshift.io/host.generated=true
Requested Host:         frontend-imgn.b9ad.pro-us-east-1.openshiftapps.com
                          exposed on router router (host elb.b9ad.pro-us-east-1.openshiftapps.com) 26 seconds ago
Path:                   <none>
TLS Termination:        <none>
Insecure Policy:        <none>
Endpoint Port:          8080

Service:        frontend
Weight:         100 (100%)
Endpoints:      10.130.35.26:8080

From above output we learn that the imgn app is available (in my case) via http://frontend-imgn.b9ad.pro-us-east-1.openshiftapps.com.

Notes

• In this containerized setup we're using Minio as the storage layer, so that different microservices can share the image data and metadata.
• You can scale the microservices as you like, they are stateless.

Following some internals, that is, screen shots from the OpenShift Web console, showing the app as a whole, events and resource consumption: