SKAFFOLD_GO_GCFLAGS should not be quoted

[briandealwis]

Expected behavior

skaffold debug provides SKAFFOLD_GO_GCFLAGS to be used in Dockerfiles to build and link Go apps in a form suitable for debugging (as per diff below). But the resulting binaries are still optimized.

--- examples/getting-started/Dockerfile
+++ examples/getting-started/Dockerfile
@@ -1,6 +1,7 @@
 FROM golang:1.12.9-alpine3.10 as builder
 COPY main.go .
-RUN go build -o /app main.go
+ARG SKAFFOLD_GO_GCFLAGS
+RUN set -x; go build -x -gcflags="${SKAFFOLD_GO_GCFLAGS}" -o /app main.go

Actual behavior

Note the crazy quoting going on with SKAFFOLD_GO_GCFLAGS, and -N -l is not applied to the actual compile command.

$ cd examples/getting-started
$ skaffold debug
...
Step 4/8 : RUN set -x; eval go build -x -gcflags="${SKAFFOLD_GO_GCFLAGS}" -o /app main.go
 ---> Running in 664f5bbb3f87
+ eval go build -x '-gcflags='"'"'all=-N -l'"'" -o /app main.go
+ go build -x '-gcflags=all=-N -l' -o /app main.go
WORK=/tmp/go-build764272742
mkdir -p $WORK/b003/
cat >$WORK/b003/importcfg << 'EOF' # internal
# import config
EOF
cd /usr/local/go/src/errors
/usr/local/go/pkg/tool/linux_amd64/compile -o $WORK/b003/_pkg_.a -trimpath $WORK/b003 -N -l -p errors -std -complete -buildid KFi9vraCRHkOkiSJsJ9s/KFi9vraCRHkOkiSJsJ9s -goversion go1.12.9 -D "" -importcfg $WORK/b003/importcfg -pack -c=2 ./errors.go

Skaffold is single-quoting the environment value set:
https://github.com/GoogleContainerTools/skaffold/blob/master/pkg/skaffold/docker/build_args.go#L34-L35

The use of the build argument requires being quoted:

$ diff
+ARG SKAFFOLD_GO_GCFLAGS
+RUN go build -gcflags=${SKAFFOLD_GO_GCFLAGS} -o /app main.go

$ skaffold debug
Step 4/8 : RUN go build -gcflags=${SKAFFOLD_GO_GCFLAGS} -o /app main.go
 ---> Running in e6ca8ab10074
flag provided but not defined: -l'
usage: go build [-o output] [-i] [build flags] [packages]
Run 'go help build' for details.

We just need to remove the single-quoting of the build definition.area

Workaround

To make this work, use eval go build -gcflags="${SKAFFOLD_GO_GCFLAGS}" ...

Information

• Skaffold version: v1.15.0
• Operating system: macOS