# How to stack multiple environments/projects for a reproducibility repository?
**URL:** https://discourse.julialang.org/t/how-to-stack-multiple-environments-projects-for-a-reproducibility-repository/92709
**Category:** General Usage
**Tags:** pkg, environment
**Created:** [January 9, 2023, 11:01am UTC](https://discourse.julialang.org/t/how-to-stack-multiple-environments-projects-for-a-reproducibility-repository/92709 "2023-01-09T11:01:45Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@sloede](https://discourse.julialang.org/u/sloede)
#### Post date: [January 9, 2023, 11:01am UTC](https://discourse.julialang.org/t/how-to-stack-multiple-environments-projects-for-a-reproducibility-repository/92709/1 "2023-01-09T11:01:45Z")
Is it possible - and if yes, how - to stack multiple environments for a reproducibility repository? That is, I would like to have two sets of `Project.toml`/`Manifest.toml` files living outside the `DEPOT_PATH` where I am able to independently (and in a reproducible manner!) control the package versions used.
Here is my use case (hopefully this makes it clearer):
To a reproducibility repository, I have added an environment A with a `Project.toml`/`Manifest.toml` pair that specifies two packages that are used for my workload, [OrdinaryDiffEq.jl](https://github.com/SciML/OrdinaryDiffEq.jl) and [Trixi.jl](https://github.com/trixi-framework/Trixi.jl), including their dependencies. I would like to add a second environment B that only contains [PackageCompiler.jl](https://github.com/JuliaLang/PackageCompiler.jl) that allows one to compile a certain workflow using the packages from environment A.
Now, I could add PackageCompiler.jl directly to environment A, but I do not want to do this, since it might pull in additional dependencies that most people do not care about. Thus I would like to mimic the “standard” Julia setup where I have an active project (in this case, A) but where I am also able to load also packages from the default environment (which is in the `DEPOT_PATH`). The difference here is that I would like to put the “default environment” also in the reproducibility repository and have the users instantiate and use this independently.
---
### Author:  [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)
#### Post date: [January 9, 2023, 11:54am UTC](https://discourse.julialang.org/t/how-to-stack-multiple-environments-projects-for-a-reproducibility-repository/92709/2 "2023-01-09T11:54:39Z")
You can append the PackageCompiler project to the installation instructions/`make` target for creating the sysimage. See for example [https://github.com/fredrikekre/.dotfiles/blob/master/.julia/environments/nvim-lspconfig/Makefile#L52-#L53](https://github.com/fredrikekre/.dotfiles/blob/master/.julia/environments/nvim-lspconfig/Makefile#L52-#L53).
---
### Author:  [@sloede](https://discourse.julialang.org/u/sloede)
#### Post date: [January 9, 2023, 12:15pm UTC](https://discourse.julialang.org/t/how-to-stack-multiple-environments-projects-for-a-reproducibility-repository/92709/3 "2023-01-09T12:15:43Z")
Ah, do you mean one should be modifying the `LOAD_PATH` by setting `JULIA_LOAD_PATH` appropriately? E.g., with a directory structure as
```julia
myroot/
project_A/
Manifest.toml
Project.toml
project_B/
Manifest.toml
Project.toml`
```
I would first instantiate both projects individually by running
```julia
cd myroot
julia --project=project_A -e 'using Pkg; Pkg.instantiate()'
julia --project=project_B -e 'using Pkg; Pkg.instantiate()'
```
and then I could stack the environments by setting `JULIA_LOAD_PATH`, e.g., like
```julia
JULIA_LOAD_PATH="$(pwd)/project_A:$(pwd)/project_B" julia -e '...'
```
where `project_A` would now be the primary environment, and `project_B` the secondary. At least that’s what I pieced together from looking at [Code Loading · The Julia Language](https://docs.julialang.org/en/v1/manual/code-loading/#Environment-stacks) and [Constants · The Julia Language](https://docs.julialang.org/en/v1/base/constants/#Base.LOAD_PATH).
**EDIT1:** Simplified the `JULIA_LOAD_PATH` command.
**EDIT2:** Remove `@stdlib` as suggested by @fredrikekre
**EDIT3:** Accept this answer incorporating the help from @fredrikekre to make it easier for future solution seekers.
---
### Author:  [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)
#### Post date: [January 9, 2023, 12:23pm UTC](https://discourse.julialang.org/t/how-to-stack-multiple-environments-projects-for-a-reproducibility-repository/92709/4 "2023-01-09T12:23:21Z")
Yes.
Also, don’t include `@stdlib` there, add necessary stdlibs to the project environments instead.
---
### Author:  [@sloede](https://discourse.julialang.org/u/sloede)
#### Post date: [January 9, 2023, 12:25pm UTC](https://discourse.julialang.org/t/how-to-stack-multiple-environments-projects-for-a-reproducibility-repository/92709/5 "2023-01-09T12:25:50Z")
Thanks a lot for your support!
> [@fredrikekre](#):
>
> Also, don’t include `@stdlib` there, add necessary stdlibs to the project environments instead.
I included your suggestion in my example above to have everything in one piece. Thanks!
---
### Author:  [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)
#### Post date: [January 9, 2023, 12:36pm UTC](https://discourse.julialang.org/t/how-to-stack-multiple-environments-projects-for-a-reproducibility-repository/92709/6 "2023-01-09T12:36:06Z")
For the specific case of PackageCompiler you don’t need to stack them though. You can use the `project` keyword argument instead. In this case you can start Julia in the PackageCompiler project, and then pass the real project to `create_sysimg`.