Simple Ngnix container for tesging active/stdby load balancing.
The Azure Load Balancer unfortunately does not provide features such as weighed load balancing nor active/stdby setups with TCP healthchecks.
You can use this container and run it on an App Service for Containers in order to replace the Azure LB for this use case.
- using embedded TCP checks
- will redirect to the primary backend unless it is unavailable, switching to fallback backend when this occurs
- restoration to primary if primary is available again
In order to check the health of your loadbalancer by the underlying container structure you can use the /_lbcheck url. If the container is running it will reply with a 200 HTTP code with the following payload :
{ "status":"healthy" }The configuration, as for all docker containers is performed via the environnement variables.
The following mandatory variables must be provided :
| Env Var Name | Purpose |
|---|---|
| LB_PORT | Load balancing service port, usually 80 or 8080 |
| LB_BACKEND_PRIMARY | host:port of the primary serving workload |
| LB_BACKEND_FALLBACK | host:port of the fallback serving workload |
In order to run the container locally, serving an entry point with port 8080 and redirecting to backends located under 192.168.4.1:8081 and 192.168.4.1:8082 you can use the following procedure :
echo "LB_PORT=8080" >> vars.txt
echo "LB_BACKEND_PRIMARY=192.168.4.1:8081" >> vars.txt
echo "LB_BACKEND_FALLBACK=192.168.4.1:8082" >> vars.txt
docker pull zlatkoa/nginx-alsb:1.0.0
docker run -p 8080:8080 --env-file vars.txt -d --name lbexample zlatkoa/nginx-alsb:1.0.0Note : you can use a set of Helloer to simulate your backends.
Please make sure the you provide the LB_PORT, LB_BACKEND_PRIMARY and LB_BACKEND_FALLBACK envronnement variables to your pod/container deployement descriptor.
For containerized deployements you can use the image available on the Docker Hub. It is updated by the Github CI/CD worklow on each code change.
You can get the container image by issuing the following commands :
docker pull zlatkoa/nginx-alsb:1.0.0