To run these commands, you must either install docker, or the correct version of abigen.

The latter can be installed with these commands, at least on linux:

   git clone https://github.com/ethereum/go-ethereum
   cd go-ethereum/cmd/abigen
   git checkout v<version-needed>
   go install

Here, is the version of go-ethereum specified in chainlink's go.mod. This will install abigen in "$GOPATH/bin", which you should add to your $PATH.

To reduce explicit dependencies, and in case the system does not have the correct version of abigen installed , the above commands spin up docker containers. In my hands, total running time including compilation is about 13s. If you're modifying solidity code and testing against go code a lot, it might be worthwhile to generate the the wrappers using a static container with abigen and solc, which will complete much faster. E.g.

   abigen -sol ../../contracts/src/v0.6/VRFAll.sol -pkg vrf -out solidity_interfaces.go

where VRFAll.sol simply contains import "contract_path"; instructions for all the contracts you wish to target. This runs in about 0.25 seconds in my hands.

If you're on linux, you can copy the correct version of solc out of the appropriate docker container. At least, the following works on ubuntu:

   $ docker run --name solc ethereum/solc:0.6.2
   $ sudo docker cp solc:/usr/bin/solc /usr/bin
   $ docker rm solc

If you need to point abigen at your solc executable, you can specify the path with the abigen --solc option.