Running Spawn inside a Docker container

[AntoineGautier]

When I run Spawn locally from /home/reituag/gitrepo/modelica-buildings I get the following JSON intermediary file that is then used to create the FMU:

{
  "version": "0.1",
  "EnergyPlus": {
    "idf": "/home/reituag/gitrepo/modelica-buildings/Buildings/Resources/Data/ThermalZones/EnergyPlus_9_6_0/Examples/SingleFamilyHouse_TwoSpeed_ZoneAirBalance/SingleFamilyHouse_TwoSpeed_ZoneAirBalance.idf",
    "weather": "/home/reituag/gitrepo/modelica-buildings/Buildings/Resources/weatherdata/USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.epw",

However, when I run Spawn from /mnt/shared/modelica-buildings inside a Docker container, I get:

{
  "version": "0.1",
  "EnergyPlus": {
    "idf": "/tmp/JModelica.org/jm_tmpzh05d4xs/resources/0/SingleFamilyHouse_TwoSpeed_ZoneAirBalance.idf",
    "weather": "/tmp/JModelica.org/jm_tmpzh05d4xs/resources/1/USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.epw",

and the following error:

Executing '""/mnt/home/reituag/spawn/Spawn-light-0.5.0-c10e8c6d7e-Linux/bin/spawn-0.5.0-c10e8c6d7e"" energyplus create-fmu  --output-path ""/mnt/shared/modelica-buildings/spawn-AirHeating/EnergyPlus.fmu"" ""/mnt/shared/modelica-buildings/spawn-AirHeating/ModelicaBuildingsEnergyPlus.json""' failed to generate fmu '/mnt/shared/modelica-buildings/spawn-AirHeating/EnergyPlus.fmu'

So perhaps the question is how the JSON properties idf and weather are assigned and whether a specific setting is missing in my container.

Thanks for any insight.

[mwetter]

The error message looks strange to me. It contains

Executing '""/mnt/home/reituag/spawn/...

and

"/mnt/shared/modelica-buildings/spawn-AirHeating/EnergyPlus.fmu"

in the same message. This looks like your docker has spawn installed in /mnt/home/reituag (which you perhaps export to the docker as otherwise the executable would not know about its existence) and this is on the PATH before it picks up the spawn binary from /mnt/shared/modelica-buildings/....

The C code that invokes spawn searches for the spawn binary in various places, see

modelica-buildings/Buildings/Resources/src/ThermalZones/EnergyPlus_9_6_0/C-Sources/BuildingInstantiate.c

Line 383 in 8584e80

char* findSpawnExe(FMUBuilding* bui, const char* SEARCHPATH, const char* spawnExe){

Eventually, as the path to the Modelica Buildings Library is exported to the docker, and spawn knows the top-level directory name, it will find the binary of the Modelica Buildings Library. However, in your error message, it looks like spawn first finds it in /mnt/home/reituag....

[AntoineGautier]

This looks like your docker has spawn installed in /mnt/home/reituag (which you perhaps export to the docker as otherwise the executable would not know about its existence) and this is on the PATH before it picks up the spawn binary from /mnt/shared/modelica-buildings/...

Yes, I bind mount the directory with the Spawn executable, that I manually installed outside the MBL directory on the host.
This is because I am using the development branch of MBL and not the public release which comes with a bundled Spawn executable.
The PATH environment variable of the container is set to include the path where the Spawn directory is mounted in the container.
So, from within the container:

> which spawn
/mnt/home/reituag/spawn/Spawn-light-0.5.0-c10e8c6d7e-Linux/bin/spawn

But I found the solution.
I needed to mount the whole Spawn installation directory, not only the bin subdirectory with the Spawn executable as I previously did (the one that is included in the PATH). This is because epfmi.so is required at runtime and:

> tree ~/spawn/Spawn-light-0.5.0-c10e8c6d7e-Linux/
/home/reituag/spawn/Spawn-light-0.5.0-c10e8c6d7e-Linux/
├── bin
│   ├── spawn -> spawn-0.5.0-c10e8c6d7e
│   └── spawn-0.5.0-c10e8c6d7e
├── etc
│   └── Energy+.idd
├── lib
│   └── epfmi.so
└── README.md

So, replacing:

docker run -v /home/reituag/spawn/Spawn-light-0.5.0-c10e8c6d7e-Linux/bin:/mnt/home/reituag/spawn/Spawn-light-0.5.0-c10e8c6d7e-Linux/bin:ro ...

with

docker run -v /home/reituag/spawn/Spawn-light-0.5.0-c10e8c6d7e-Linux:/mnt/home/reituag/spawn/Spawn-light-0.5.0-c10e8c6d7e-Linux:ro

solved the issue for me.

Note that the error message that I shared in my previous post was taken from the OCT log file.
The error message in the terminal generated by the Spawn executable clearly pointed to the issue with the epfmi.so path.