Improve build script

[SuperQ]

• Use single gox command to parallelize build.
• Automatically package any archs gox spits out.
• Add sha256sums for packages.

[codecov]

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[oliver006]

Nice, this is a lot better than what we got right now.

[oliver006]

Release failed: https://cloud.drone.io/oliver006/redis_exporter/198/1/8

GO_LDFLAGS: -s -w -extldflags "-static" -X main.VERSION=v0.33.0 -X main.COMMIT_SHA1=09b985767518c57735b7f11b66c15808c4561db4 -X main.BUILD_DATE=2019-04-09-17:37:28
go get: warning: modules disabled by GO111MODULE=auto in GOPATH/src;
ignoring go.mod;
see 'go help modules'
go get: warning: modules disabled by GO111MODULE=auto in GOPATH/src;
ignoring go.mod;
see 'go help modules'
go: modules disabled inside GOPATH/src by GO111MODULE=auto; see 'go help modules' 

Do the go build commands in the build script need the -mod=vendor flag as well?

[oliver006]

I guess I could add -mod=vendor to the GO_LDFLAGS variable? nope, ldflags are for the linker.

Hmm, looks like gox currently doesn't support passing the vendor flag: mitchellh/gox#122

[SuperQ]

Hrm, I don't know how gox passes in those flags. You might need to add GO111MODULE: on in the env section of the drone config.

[oliver006]

Good suggestion, let me try that.

[SuperQ]

It may also need -mod=vendor on the GO_LDFLAGS in order to enforce the use of the vendor dir.

[oliver006]

Setting the env var seems to have fixed the build, now on to the next issue:

rm: cannot remove 'dist/redis_exporter-v0.33.0.windows-386.zip': No such file or directory

I guess we got to ignore errors here cause for the first zip there's nothing to delete.

[SuperQ]

Ahh, yea, [[ -f $f ]] && rm $f. Forgot that rm fails on removal of nothing.