add_collection_format fails in gdalcubes_r docker rstudio

[mstrahl]

I tried to define a new format for our Sentinel-2 Global Mosaic ARD stored on our own cloud storage:
the add_collection_format() fails:
'> add_collection_format("https://pta.fmi.fi/~strahlen/FMI-s2gm-cogs.json")
Error in file(con, "r") : cannot open the connection
In addition: Warning messages:
1: In download.file(url, destfile = destfile) :
URL https://pta.fmi.fi/~strahlen/FMI-s2gm-cogs.json: cannot open destfile '/usr/local/lib/R/site-library/gdalcubes/formats/FMI-s2gm-cogs.json', reason 'Permission denied'
2: In download.file(url, destfile = destfile) :
download had nonzero exit status
3: In file(con, "r") :
cannot open file '/usr/local/lib/R/site-library/gdalcubes/formats/FMI-s2gm-cogs.json': No such file or directory'

I am using the gdalcubes_r docker image, so there you should define the directory as writable.