pass authprovider to buildkit session

[ndeloof]

What I did
Aligned compose build code with https://github.com/docker/buildx/blob/master/commands/build.go

Related issue
#1545

[ndeloof]

@tonistiigi could you please confirm this is the correct way?
i.e. GetDriver already has an Auth parameter we pass docker config file, why do we also have to set this as Session option?

[gtardif]

LGTM, Just pending @tonistiigi confirmation

[ndeloof]

go.mod is killing me ...

[tonistiigi]

i.e. GetDriver already has an Auth parameter we pass docker config file, why do we also have to set this as Session option?

Yes, both are needed. GetDriver is only used when pulling buildkit image itself for creating the builder container one time. That image is public but we pass auth to avoid registry side rate-limiting.

[ndeloof]

dependency issue:
buildx authprovider import introduced in this PR relies on containerd 1.5.x
kube backend relies on helm -> deislabs/oras -> containerd 1.4.x

1.4 -> 1.5 containerd updated PushContent signature to add some new parameters.
As Goland does not support polymorphism nor default parameter values (welcome into XXIth century) this is a backward compatibility break, which require a whole ecosystem of callers to update their code.

I can't find any possible workaround here 😱

[gtardif]

A quick comment to explain this hack would be useful in the future...

[gtardif]

LGTM with nit (comment on go mod replace)