[R-sig-Debian] Update on docker Python:3 and adding R:4.x

[Dirk Eddelbuettel]

On 24 June 2020 at 15:15, Dave Lange wrote:
|  I continue to receive an error installing R via dockerfile on a buster
| image python:3.
| E: The value 'buster-cran40' is invalid for APT::Default-Release as such a
| release is not available in the sources

Do you have the Dockerfile in public repo we can look at?

| My starting point is the debian buster based Python:3 image adding a couple

This is an R list so please tell us more about Python:3. What it is based on?

Hypothetically, could you just start from debian:buster, add python3 and then
add the buster-cran40 repo by Johannes?

| of python specific configurations and then using the commands in the R
| project documentation for installing R on Buster. I got slightly different
| answers when I used apt versus apt-get. There were warnings about
| unverified sources solved by a reference to the certificate key.

You generally must install a key to validate a repository. This could even be
your error.

In any event, this is all "academic". Maybe bring us the famous "MCVE": a
minimally complete verifiable example. Otherwise we have simply no idea what
you may be doing.

| It turns out building the python container and commenting the R commands
| out allowed me to manually step through my dockerfile lines. Its repeatable
| that the R install fails with the error above when in the dockerfile.
| Running the commands manually allows the installation to finish
| successfully.  I sense that docker is multithreaded and hits the "use
| buster-cran40" before it defines buster-cran40. Manually stepping through

I doubt that. Docker is very carefully "layered". Each RUN command results in
one layer on filesystem. You can build them one by one. There is no
concurrency as each subsequent RUN needs / depends upon previous ones.

| the commands keeps the preferred order. At this point I'm happy with a
| repeatable process.
| 
| It sounds like I have been re-inventing the wheel, which has been
| educational for me. If someone wants to change my starting point to
| something that already has stable/latest production for debian, Python3 and
| R4 and will be updated for the future I would appreciate the head start.

Should be easy. Look at the variety of Dockerfiles is maintain inside the
Rocker Project -- while most are based on Debian's testing release you can
still look at them (though note that some are also Ubuntu based)

You could start at  https://github.com/rocker-org/rocker  but also look at
other repositories in the same org at GH.

Dirk

-- 
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