Todo sample for Kubernetes

Configurable settings

Store config in the environment (aka the 12-factor app principles).

Public accessible endpoint for todoapi backend, defined in config.local.yml:

• TODOAPI_HOST : default = localhost
• TODOAPI_PORT : default = 30080
• TODOAPI_PATH : default = /api/todo

A version for deployment on the cloud is also provided in config.cloud.yml:

• TODOAPI_HOST : external IP (static) or domain name allocated by cloud providers.
• TODOAPI_PORT : default = 80
• TODOAPI_PATH : default = /api/todo

Architecture

A dockerized web app with separate frontend and backend services on Kubernetes (both locally and on the cloud).

Frontend

Static HTML5 files and jQuery scripts.

Local web endpoint:

• host = localhost
• port = 30000

Cloud web endpoint:

• host = external IP (ephemeral) or domain name allocated by cloud providers
• port = 80

Backend

Backend program written in ASP.NET Core.

Local API endpoint:

• host = localhost
• port = TODOAPI_PORT (default = 30080)
• path = TODOAPI_PATH (default = /api/todo)

Cloud API endpoint:

• host = TODOAPI_HOST (to be revised in config.cloud.yml), external IP (static) or domain name allocated by cloud providers
• port = TODOAPI_PORT (default = 80)
• path = TODOAPI_PATH (default = /api/todo)

Usage: the local case

Preparation

1. Create a todo namespace for this app:

   % kubectl create ns todo
   

2. Load the ConfigMap content:

   % kubectl apply -f k8s/local/config.local.yml  -n todo
   % kubectl get configmaps  -n todo
   

Build & Run

1. Using Skaffold to streamline the build-and-run processes continuously:

   % skaffold dev  -n todo
   

2. Use your browser to visit the web app at http://localhost:30000

Canary

1. See the number of pods in the deployments, including the canary part of the todoapi service:

   % kubectl get deployments -n todo
   NAME             DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
   todoapi          3         3         3            3           14s
   todoapi-canary   1         1         1            1           14s
   todofrontend     3         3         3            3           14s
   

2. Scale the canary part from 1 to 2, either by:

   % kubectl scale --replicas=2 deployment/todoapi-canary  -n todo
   

   or by:

   % kubectl patch deployment todoapi-canary \
       --patch "$(cat todoapi-canary-patch.yml)" -n todo
   

3. See again the number of pods in the deployments, including the canary part of the todoapi service:

   % kubectl get deployments -n todo
   NAME             DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
   todoapi          3         3         3            3           2m
   todoapi-canary   2         2         2            2           2m
   todofrontend     3         3         3            3           2m
   
   % kubectl get pods -n todo
   NAME                              READY   STATUS    RESTARTS   AGE
   todoapi-77f54c6f5d-9dkjh          1/1     Running   0          2m
   todoapi-77f54c6f5d-grmfs          1/1     Running   0          2m
   todoapi-77f54c6f5d-rdk7p          1/1     Running   0          2m
   todoapi-canary-549dd65797-2rdxf   1/1     Running   0          2m
   todoapi-canary-549dd65797-mn7db   1/1     Running   0          42s
   todofrontend-67cc74bcbb-2zw4x     1/1     Running   0          2m
   todofrontend-67cc74bcbb-w6fz5     1/1     Running   0          2m
   todofrontend-67cc74bcbb-wdhmh     1/1     Running   0          2m
   

Usage: the cloud case

Preparation

1. If you're using GKE, do the gke-steps first.

2. Fill in correct image names by modifying the PROJECT_ID string in skaffold.yaml file:

   % vi skaffold.yaml
   

3. Fill in correct image names by modifying the PROJECT_ID string in manifest files, by either:

   % k8s/cloud/fix-name.py  write_your_real_project_id_here
   

   or by the following if there's no Python3 installed in your Windows:

   C:> docker run  -v %cd%:/mnt  python:3-alpine  \
       /mnt/k8s/cloud/fix-name.py  write_your_real_project_id_here
   

4. Create a todo namespace for this app:

   % kubectl create ns todo
   

5. Load the ConfigMap content (GCP/GKE for example):

   # reserve a new static external IP address for backend todoapi
   % gcloud compute addresses create todoapi --region=us-west1 --network-tier=PREMIUM
   
   # make sure the static external IP address has been allocated
   % gcloud compute addresses list
   
   # replace the placeholder string "111.222.333.444" with the allocated IP address
   % vi k8s/cloud/config.cloud.yml
   % vi k8s/cloud/todoapi-service.yml
   
   #...
   
   # now, load it!
   % kubectl apply -f k8s/cloud/config.cloud.yml  -n todo
   % kubectl get configmaps  -n todo
   

Build & Run

1. Using Skaffold to streamline the build-and-run process continuously:

   % skaffold run -p cloud  -n todo
   

2. Use your browser to visit the web app at http://FRONTEND_EXTERNAL_IP:80

Canary

1. See the number of pods in the deployments, including the canary part of the todoapi service:

   % kubectl get deployments -n todo
   NAME             DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
   todoapi          3         3         3            3           14s
   todoapi-canary   1         1         1            1           14s
   todofrontend     3         3         3            3           14s
   

2. Scale the canary part from 1 to 2, either by:

   % kubectl scale --replicas=2 deployment/todoapi-canary  -n todo
   

   or by:

   % kubectl patch deployment todoapi-canary \
       --patch "$(cat todoapi-canary-patch.yml)" -n todo
   

3. See again the number of pods in the deployments, including the canary part of the todoapi service:

   % kubectl get deployments -n todo
   NAME             DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
   todoapi          3         3         3            3           2m
   todoapi-canary   2         2         2            2           2m
   todofrontend     3         3         3            3           2m
   
   % kubectl get pods -n todo
   NAME                              READY   STATUS    RESTARTS   AGE
   todoapi-77f54c6f5d-9dkjh          1/1     Running   0          2m
   todoapi-77f54c6f5d-grmfs          1/1     Running   0          2m
   todoapi-77f54c6f5d-rdk7p          1/1     Running   0          2m
   todoapi-canary-549dd65797-2rdxf   1/1     Running   0          2m
   todoapi-canary-549dd65797-mn7db   1/1     Running   0          42s
   todofrontend-67cc74bcbb-2zw4x     1/1     Running   0          2m
   todofrontend-67cc74bcbb-w6fz5     1/1     Running   0          2m
   todofrontend-67cc74bcbb-wdhmh     1/1     Running   0          2m
   

Kubernetes dashboard

See here if you'd like to use Kubernetes dashboard locally.

About the source code

The sample was extracted from the TodoApi demo in the Microsoft Docs site, retrieved on Feb 14, 2019:

• Document - Tutorial: Create a web API with ASP.NET Core MVC

• Source code - https://github.com/aspnet/Docs/tree/master/aspnetcore/tutorials/first-web-api/samples/2.2/TodoApi

The original source code to be used in this repo is packed in the TodoApi-original.zip file for your reference.

LICENSE

Apache License 2.0. See the LICENSE file.

History

7.0: Support canary release.

6.0: Support Kubernetes on the cloud (GKE for example).

5.0: Support ConfigMap and naming convention.

4.1: Use Kubernetes dashboard.

4.0: Support Kubernetes (locally).

3.0: Separate frontend and backend into 2 distinct containers.

2.0: Dockerize the app with simple Dockerfile and docker-compose.yml.

1.0: Extracted from Microsoft Docs.