cocalc : how to add a julia kernel?

I have installed cocalc image on google cloud (https://github.com/sagemathinc/cocalc-docker/blob/master/Dockerfile)I have tried to add julia 1.4 kernel to jupyter but it failed.I have set .julia to be here : /usr/local/share/.julia.

Config

julia bin directory : /opt/julia/bin/julia

ln -s /opt/julia/bin/julia /usr/local/bin

IJulia is installed

using Pkg ;Pkg.add("IJulia");

etc/julia/startup.jl

ENV["JULIA_DEPOT_PATH"] = "/usr/local/share/.julia" ; ENV["JUPYTER"] = "/usr/local/bin/jupyter"; 

/usr/local/share/jupyter/kernels/julia-1.4/kernel.json

{"display_name": "Julia 1.4.0","argv": ["/opt/julia/bin/julia","-i","--startup-file=yes","--color=yes","--project=@.","/usr/local/share/.julia/packages/IJulia/yLI42/src/kernel.jl","{connection_file}"  ],"language": "julia","env": {},"interrupt_mode": "signal"}

Error I get

sh-4.4$ jupyter console --kernel=julia-1.4ERROR: LoadError: ArgumentError: Package IJulia not found in current path:- Run `import Pkg; Pkg.add("IJulia")` to install the IJulia package.Stacktrace:[1] require(::Module, ::Symbol) at ./loading.jl:892[2] include(::Module, ::String) at ./Base.jl:377[3] exec_options(::Base.JLOptions) at ./client.jl:288[4] _start() at ./client.jl:484

It seems that I don't understand Julia package management for projects (""--project=@." options in kernel.json).

EDITaccording to the julia Pkg Doc, the --project=@. command line tags makes Julia search for *.toml files in parent directories. But even by changing ./julia directory to the project parent directory, it does not work.

Thanks in advance for your help.