25.5 Models using Docker

This section will discuss how to add new models to PEcAn docker. To be able to add a new model to PEcAn when using docker is as simple as starting a new container. The model will come online and let the PEcAn framework know there is a new model available, there is no need to go through the process of registering this model with PEcAn. Users will be able to select this new model from web interface and run with this model selected.

For this process to work a docker image of the model will need to be created as well as small json file that is used to announce this new model. A separate service in PEcAn (monitor) will use this json file to keep track of all models available as well as register these models with PEcAn.

Model information Model build Common problems

25.5.1 Model information

Each model will have a small json file called model_info.json that is used to describe the model and used by the monitor service to register the model with PEcAn. This file will contain information about the model that is send as part of the heartbeat of the container to the monitor service. Below is an example of this file for the ED model. The required fields are name, type, version and binary. The fields type and version are used by PEcAn to send the messages to RabbitMQ. There is no need to specify the queue name explicitly. The queue name will be created by combining these two fields with an underscore. The field binary is used to point to the actual binary in the docker container.

There are 2 special values that can be used, @VERSION@ which will be replaced by the version that is passed in when building the container, and @BINARY@ which will be replaced by the binary when building the docker image.

  "name": "ED2.2",
  "type": "ED2",
  "version": "@VERSION@",
  "binary": "@BINARY@",
  "description": "The Ecosystem Demography Biosphere Model (ED2) is an integrated terrestrial biosphere model incorporating hydrology, land-surface biophysics, vegetation dynamics, and soil carbon and nitrogen biogeochemistry",
  "author": "Mike Dietze",
  "contributors": ["David LeBauer", "Xiaohui Feng", "Dan Wang", "Carl Davidson", "Rob Kooper", "Shawn Serbin", "Alexey Shiklomanov"],
  "links": {
    "source": "https://github.com/EDmodel/ED2",
    "issues": "https://github.com/EDmodel/ED2/issues"
  "inputs": {},
  "citation": ["Medvigy D., Wofsy S. C., Munger J. W., Hollinger D. Y., Moorcroft P. R. 2009. Mechanistic scaling of ecosystem function and dynamics in space and time: Ecosystem Demography model version 2. J. Geophys. Res. 114 (doi:10.1029/2008JG000812)"]

Other fields that are recommended, but currently not used yet, are:

  • description : a longer description of the model.
  • creator : contact person about this docker image.
  • contribuor : other people that have contributed to this docker image.
  • links : addtional links to help people when using this docker image, for example values that can be used are source to link to the source code, issues to link to issue tracking system, and documentation to link to model specific documentation.
  • citation : how the model should be cited in publications.

25.5.2 Model build

In general we try to minimize the size of the images. To be able to do this we split the process of creating the building of the model images into two pieces (or leverage of an image that exists from the original model developers). If you look at the example Dockerfile you will see that there are 2 sections, the first section will build the model binary, the second section will build the actual PEcAn model, which copies the binary from the first section.

This is an example of how the ED2 model is build. This will install all the packages needed to build ED2 model, gets the latest version from GitHub and builds the model.

The second section will create the actual model runner. This will leverage the PEcAn model image that has PEcAn already installed as well as the python code to listen for messages and run the actual model code. This will install some additional packages needed by the model binary (more about that below), copy the model_info.json file and change the @VERSION@ and @BINARY@ placeholders.

It is important values for type and version are set correct. The PEcAn code will use these to register the model with the BETY database, which is then used by PEcAn to send out a message to a specfic worker queue, if you do not set these variables correctly your model executor will pick up messages for the wrong model.

To build the docker image, we use a Dockerfile (see example below) and run the following command. This command will expect the Dockerfile to live in the model specific folder and the command is executed in the root pecan folder. It will copy the content of the pecan folder and make it available to the build process (in this example we do not need any additional files).

Since we can have multiple different versions of a model be available for PEcAn we ar using the following naming schema pecan/model-<modeltype>-<version>:<pecan version. For example the image below will be named pecan/model-ed2-git, since we do not specify the exact version it will be atomically be named pecan/model-ed2-git:latest.

docker build \
    --tag pecan/model-ed2-git \
    --file models/ed/Dockerfile \

Example of a Dockerfile, in this case to build the ED2 model.

# ----------------------------------------------------------------------
# ----------------------------------------------------------------------
FROM pecan/models:${IMAGE_VERSION} as model-binary

# Some variables that can be used to set control the docker build

# install dependencies
RUN apt-get update \
    && apt-get install -y --no-install-recommends \
       build-essential \
       curl \
       gfortran \
       git \
       libhdf5-dev \
       libopenmpi-dev \
    && rm -rf /var/lib/apt/lists/*

# download, unzip and build ed2
RUN git -c http.sslVerify=false clone https://github.com/EDmodel/ED2.git \
    && cd ED2/ED/build \
    && curl -o make/include.mk.VM http://isda.ncsa.illinois.edu/~kooper/EBI/include.mk.opt.Linux \
    && if [ "${MODEL_VERSION}" != "git" ]; then git checkout ${MODEL_VERSION}; fi \
    && ./install.sh -g -p VM


# ----------------------------------------------------------------------
# ----------------------------------------------------------------------
FROM pecan/models:latest

# ----------------------------------------------------------------------
# ----------------------------------------------------------------------

RUN apt-get update \
    && apt-get install -y --no-install-recommends \
       libgfortran3 \
       libopenmpi2 \
    && rm -rf /var/lib/apt/lists/*

# ----------------------------------------------------------------------
# ----------------------------------------------------------------------

# Some variables that can be used to set control the docker build

# Setup model_info file
COPY models/ed/model_info.json /work/model.json
RUN sed -i -e "s/@VERSION@/${MODEL_VERSION}/g" \
           -e "s#@BINARY@#/usr/local/bin/ed2.${MODEL_VERSION}#g" /work/model.json

# COPY model binary
COPY --from=model-binary /src/ED2/ED/build/ed_2.1-opt /usr/local/bin/ed2.${MODEL_VERSION}

WARNING: Dockerfile environment variables set via ENV are assigned all at once; they do not evaluate successively, left to right. Consider the following block:

# Don't do this!

In this block, the expansion for setting MODEL_TYPE_VERSION is not aware of the current values of MODEL_TYPE or MODEL_VERSION, and will therefore be set incorrectly to just _ (unless they have been set previously, in which case it will be aware only of their earlier values). As such, variables depending on other variables must be set in a separate, subsequent ENV statement than the variables they depend on.

Once the model has build and is working we can add it to the PEcAn stack and be able to use this model in the web interface. There are two methods to start this new model. First, we can add it to the docker-compose.yml file and start the container using docker-compose -p pecan -d up.

    image: pecan/model-ed2-git
      - pecan
      - pecan:/data
       - rabbitmq
    restart: unless-stopped

Alternatively we can start the container manually using the following command.

docker run \
    --detach \
    --rm \
    --name pecan-ed2-git \
    --networks pecan_pecan \
    --volume pecan_pecan:/data

25.5.3 Common problems

Following are some solutions for common problems that you might encounter when building the docker images for a model.

25.5.4 Debugging missing libraries

When building the model binary it might require specific libraries to be installed. In the second stage the model binary is copied into a new image, which could result in the binary missing specific libraries. In the case of the ED2 model the following was used to find the libraries that are needed to be installed (libgfortran5 and libopenmpi3).

The first step is to build the model using the Dockerfile (in this case the ap-get install was missing in the second stage).

Step 5/9 : RUN git clone https://github.com/EDmodel/ED2.git     && cd ED2/ED/build     && curl -o make/include.mk.VM http://isda.ncsa.illinois.edu/~kooper/EBI/include.mk.opt.`uname -s`     && if [ "${MODEL_VERSION}" != "git" ]; then git checkout ${MODEL_VERSION}; fi     && ./install.sh -g -p VM
make[1]: Leaving directory '/src/ED2/ED/build/bin-opt-E'
Installation Complete.
Removing intermediate container a53eba9a8fc1
 ---> 7f23c6302130
Step 6/9 : FROM pecan/executor:latest
 ---> f19d81b739f5
Step 9/9 : COPY --from=model-binary /src/ED2/ED/build/ed_2.1-opt /usr/local/bin/ed2.${MODEL_VERSION}
 ---> 07ac841be457
Successfully built 07ac841be457
Successfully tagged pecan/pecan-ed2:latest

At this point we have created a docker image with the binary and all PEcAn code that is needed to run the model. Some models (especially those build as native code) might be missing additional packages that need to be installed in the docker image. To see if all libraries are installed for the binary.

> docker run -ti --rm pecan/pecan-ed2 /bin/bash
root@8a95ee8b6b47:/work# ldd /usr/local/bin/ed2.git  | grep "not found"
    libmpi_usempif08.so.40 => not found
    libmpi_usempi_ignore_tkr.so.40 => not found
    libmpi_mpifh.so.40 => not found
    libmpi.so.40 => not found
    libgfortran.so.5 => not found

Start the build container again (this is the number before the line FROM pecan/executor:latest, 7f23c6302130 in the example), and find the missing libraries listed above (for example libmpi_usempif08.so.40):

> docker run --rm -ti 7f23c6302130
root@e716c63c031f:/src# dpkg -S libmpi_usempif08.so.40
libopenmpi3:amd64: /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi_usempif08.so.40.10.1
libopenmpi3:amd64: /usr/lib/x86_64-linux-gnu/libmpi_usempif08.so.40.10.1
libopenmpi3:amd64: /usr/lib/x86_64-linux-gnu/libmpi_usempif08.so.40

This shows the pages is libopenmpi3 that needs to be installed, do this for all missing packages, modify the Dockerfile and rebuild. Next time you run the ldd command there should be no more packages being listed.