Upgrade docker images from 20.04 to 22.04

[g2flyer]

Title mostly says it all. Main trigger was that client docker image had too old a cmake ("thanks" to a 1/16 change) to build contracts in pdo-contracts. That said, 20.04 of course is also a bit dated and EOL if in a year.

Tested by running the usual make test here and by mounting pdo-contracts into a client container and then run make test in it (which admittedly initially failed in the inference tests but that was due to the guardian requiring an apt install libgl1 libcudart11.0 to work properly! After running that make test also worked for pdo-contracts => Q: should we add these dependencies also to pdo_client.dockerfile?)

[cmickeyb]

have you tested with host install mode as well?

[g2flyer]

have you tested with host install mode as well?

Nope, i just wanted to make docker images work with pdo-contract which now (implicitly) requires 22.04. Hence i've also not updated any docu that 22.04 is now the default (which i think Prakash has something against :-)

[prakashngit]

Are we dropping docker support for 20.04? If this PR is about adding support for 22.04 in addition to 20.04, I am in favor. I am not in favor of dropping docker support for 20.04, given that PDO itself is supported for 20.04 ONLY as of now. Until we officially move PDO to 22.04, we should retain docker support for 20.04. If docker fails in 20.04 due to a recent commit, IMHO we should revert those commits.

[g2flyer]

re we dropping docker support for 20.04? If this PR is about adding support for 22.04 in addition to 20.04, I am in favor. I am not in favor of dropping docker support for 20.04, given that PDO itself is supported for 20.04 ONLY as of now.

You still will be able to build docker with ubuntu 20.04, it just wouldn't be the default anymore. You just have to specify UBUNTU_VERSION and UBUNTU_NAME docker build variables, e.g., via adding to make.loc a line with export DOCKER_BUILDARGS=--build-arg UBUNTU_VERSION=20.04 --build-arg UBUNTU_NAME=focal. (Note: ubu 20.04 does have a python3 package (but 22.04 no python!), so the package change is fine and the sdk is the same for 20.04 and newer, so we don't need that conditional anymore ...)

[prakashngit]

Thank you. Tested using 'make test' on a fresh VM. Haven't tested the containers against examples from the contract repo. One very minor comment is that on the https://github.com/hyperledger-labs/private-data-objects/blob/main/docs/docker.md doc, it would be good to say that one needs to have make installed as well to create the docker images. Not sure if the version matters. Thanks!