make generate fails under podman due to unset $HOME, and is subtly broken under docker

[intelfx]

Invoking make generate (or, equivalently, .dapper generate) fails at go generate:

Unmodified tree build log with podman

make-generate.log

$ make generate
./.dapper generate
<...>
COMMIT k3s:master
--> c5d9ede7f540
Successfully tagged localhost/k3s:master
c5d9ede7f5401ce8ec923b746df13e3510c573a975a9b650c367e1980a3ce6c5
Running: go generate
go: downloading github.com/sirupsen/logrus v1.9.3
<...>
go: downloading github.com/gofrs/uuid v4.4.0+incompatible
build cache is required, but could not be located: GOCACHE is not defined and neither $XDG_CACHE_HOME nor $HOME are defined
main.go:1: running "go": exit status 1
FATA[0074] exit status 1
make: *** [Makefile:13: generate] Error 1

This presumably happens because Dockerfile.dapper sets HOME=${DAPPER_SOURCE} in the same statement as DAPPER_SOURCE=..., which is then not substituted correctly. The problem is not immediately visible on docker only because docker resets an unset $HOME to /root:

Patched tree build log with docker, with changes to make the problem visible

make-generate-docker.log

$ git diff
diff --git a/Dockerfile.dapper b/Dockerfile.dapper
index af99d3d35e..81b5af3184 100644
--- a/Dockerfile.dapper
+++ b/Dockerfile.dapper
@@ -56,7 +56,7 @@ ENV DAPPER_RUN_ARGS="--privileged -v k3s-cache:/go/src/github.com/k3s-io/k3s/.ca
     DAPPER_SOURCE="/go/src/github.com/k3s-io/k3s/" \
     DAPPER_OUTPUT="./bin ./dist ./build/out ./build/static ./pkg/static ./pkg/deploy" \
     DAPPER_DOCKER_SOCKET=true \
-    HOME=${DAPPER_SOURCE} \
+    HOME= \
     CROSS=true \
     STATIC_BUILD=true

diff --git a/scripts/generate b/scripts/generate
index ebdaf31cc5..142592f36f 100755
--- a/scripts/generate
+++ b/scripts/generate
@@ -8,4 +8,6 @@ mkdir -p build/data
 GO=${GO-go}

 echo Running: "${GO}" generate
+env | grep HOME=
+exit 1
 "${GO}" generate

$ make generate
./.dapper generate
<...>
Successfully tagged k3s:master

Running: go generate
HOME=/root
FATA[0002] exit status 1
make: *** [Makefile:13: generate] Error 1

Still, this causes the Go cache (mounted at /go/src/github.com/k3s-io/k3s/.cache) to be effectively broken and unused because $HOME doesn't point to it.

[brandond]

Not sure this needs any other testing, since it's just used at build time.