Nested Podman with eWaterCycle

If for some reason you want to run the eWaterCycle platform from within a container, this is possible using podman.

There are a few steps you will have to go through. While podman is a drop-in replacement for docker, the ewatercycle Python package does not support it yet. However, as a technical demonstration, the essential steps below show:

1. starting a container image with both podman and ewatercycle
   • plus forcing data for a model
2. starting a headless container of a grpc4bmi enabled model
   • including mounting the forcing data
3. connecting to that model with grpc4bmi and initializing the model

How to run

First install podman on your local machine.

Then run the following image (in a rootless configuration):

podman run -it \
--security-opt label=disable \
--user podman \
--device /dev/fuse \
docker.io/bschilperoort/hbv-podman:latest /bin/bash

This container has model forcing data in the /home/podman/forcing direcory.

Inside this container you can start another container with podman. We start this one headless (-d) and specify a bind mount for the forcing directory:

podman run \
-d \
--mount type=bind,source=/home/podman/forcing,target=/home/podman/forcing \
ghcr.io/ewatercycle/hbv-bmi-grpc4bmi:latest

After starting the container we can activate the ewatercycle conda environment and start Python:

conda activate ewatercycle
python

Here we can connect to the model and initialize it with the prepared config file:

>>> import grpc
>>> from grpc4bmi.bmi_grpc_client import BmiClient
>>> import numpy as np
>>> 
>>> mymodel = BmiClient(grpc.insecure_channel("localhost:55555"))
>>> mymodel.initialize("/home/podman/forcing/HBV_config.json")
>>> mymodel.get_component_name()
'HBV'

>>> mymodel.update()
>>> mymodel.get_value("Q", np.array([0.]))
array([0.00141273])

Containers

The Dockerfiles to the containers are in the subdirectories in this repository.

The containers are published on Docker Hub (ewc-podman and hbv-podman).

If the images are rebuilt at some point (and still have tag latest) you will need to clear the podman cache:

podman system prune --all --force && podman rmi --all