build: Few minor makefile and dockerfile improvements

[errordeveloper]

No description provided.

[coveralls]

Coverage increased (+0.02%) to 46.791% when pulling 64aee22 on pr/errordeveloper/makefile-improvements into 3e5ced9 on master.

[errordeveloper]

test-me-please

[aanm]

LGTM, regarding copyright headers I think @joestringer was looking into having a smaller version of them

[joestringer]

Cool, any metrics yet on whether this changes anything? Build times anywhere? Binary sizes? I realize this isn't intended as an optimization, but it'd be nice to know that we don't see any kind of regressions.

A few minor comments attached.

[gandro]

The Hubble related changes look good to me! Great cleanup! A +1 for me on the SPDX identifiers.

[errordeveloper]

Cool, any metrics yet on whether this changes anything? Build times anywhere? Binary sizes?

The fact that we got rid of dependency declaration will have some effect on build times, I should go and find out what it is, but I suspect the effect to be marginal, but it may as well end up being equal to time it takes to call find :) In the best case scenario, the local incremental builds will be faster, but CI is unlikely to be affected. We will need to do more to make use of Go build cache in CI, and in Dockerized builds more generally.

[errordeveloper]

Ok, so more on build performance.

So here is an example of how things look on master now:

$ time make -C operator clean
rm -f cilium-operator
CGO_ENABLED=0 go clean 
make -C operator clean  1.03s user 1.23s system 651% cpu 0.347 total
$ time make -C operator      
CGO_ENABLED=0 go build  -ldflags '-X "github.com/cilium/cilium/pkg/version.Version=1.7.90 263fbd5df 2020-04-10T17:43:59+02:00 go version go1.14 darwin/amd64" -s -w -X "github.com/cilium/cilium/pkg/envoy.RequiredEnvoyVersionSHA=a3385205ad620550b35d3b0b651e40898386e6e3" -X "github.com/cilium/cilium/pkg/datapath/loader.DatapathSHA="'  -o cilium-operator
make -C operator  4.82s user 2.36s system 247% cpu 2.892 total
$ time make -C operator 
make: `cilium-operator' is up to date.
make -C operator  0.23s user 0.05s system 100% cpu 0.283 total
$ 

With this change it looks more like this:

 $ time make -C operator clean
rm -f cilium-operator
go clean 
make -C operator clean  0.97s user 1.18s system 673% cpu 0.320 total
$ time make -C operator      
CGO_ENABLED=0 go build  -ldflags ' -X "github.com/cilium/cilium/pkg/version.Version=1.7.90 10674d0b2 2020-04-15T19:08:26+01:00 go version go1.14 darwin/amd64" -s -w -X "github.com/cilium/cilium/pkg/envoy.RequiredEnvoyVersionSHA=a3385205ad620550b35d3b0b651e40898386e6e3" -X "github.com/cilium/cilium/pkg/datapath/loader.DatapathSHA=" '  -o cilium-operator
make -C operator  4.21s user 2.36s system 249% cpu 2.626 total
$ time make -C operator 
CGO_ENABLED=0 go build  -ldflags ' -X "github.com/cilium/cilium/pkg/version.Version=1.7.90 10674d0b2 2020-04-15T19:08:26+01:00 go version go1.14 darwin/amd64" -s -w -X "github.com/cilium/cilium/pkg/envoy.RequiredEnvoyVersionSHA=a3385205ad620550b35d3b0b651e40898386e6e3" -X "github.com/cilium/cilium/pkg/datapath/loader.DatapathSHA=" '  -o cilium-operator
make -C operator  1.62s user 1.90s system 677% cpu 0.520 total
$

So there is no more make: cilium-operator' is up to date.`, but in my view that was flawed anyway.

The way dependencies are checked is largely inaccurate and hard to maintain (i.e. makefile of each of the components looked for .go files in some set of directories (probably most of the cases just initial set of deps that never got updated), and it ignore all of the external dependencies.

We could fix the nature of dependency calculation and base it on go list, but that shouldn't make any practical different over relying on go build, which does the same thing for us already.

[errordeveloper]

test-me-please

[errordeveloper]

test-me-please

[errordeveloper]

test-with-kernel

[errordeveloper]

@joestringer this is good to go now, I believe? If so, would you mind approving and merging please?