refactor: use Go 1.18 buildinfo (#2541)

Dockerfile

@@ -19,22 +19,12 @@ ENV GO111MODULE=on \
     GOARM=${TARGETVARIANT}
 
 WORKDIR /go/src/github.com/open-policy-agent/gatekeeper
-
-COPY pkg/ pkg/
-COPY third_party/ third_party/
-COPY vendor/ vendor/
-COPY main.go main.go
-COPY apis/ apis/
-COPY go.mod .
-
-RUN go build -mod vendor -a -ldflags "${LDFLAGS:--X github.com/open-policy-agent/gatekeeper/pkg/version.Version=latest}" -o manager main.go
+COPY . .
+RUN go build -mod vendor -a -ldflags "${LDFLAGS:--X github.com/open-policy-agent/gatekeeper/pkg/version.Version=latest}" -o manager
 
 FROM $BASEIMAGE
 
 WORKDIR /
-
 COPY --from=builder /go/src/github.com/open-policy-agent/gatekeeper/manager .
-
 USER 65532:65532
-
 ENTRYPOINT ["/manager"]

Makefile

@@ -40,14 +40,7 @@ BENCHMARK_FILE_NAME ?= benchmarks.txt
 ROOT_DIR := $(shell dirname $(realpath $(firstword $(MAKEFILE_LIST))))
 BIN_DIR := $(abspath $(ROOT_DIR)/bin)
 
-BUILD_COMMIT := $(shell ./build/get-build-commit.sh)
-BUILD_TIMESTAMP := $(shell ./build/get-build-timestamp.sh)
-BUILD_HOSTNAME := $(shell ./build/get-build-hostname.sh)
-
 LDFLAGS := "-X github.com/open-policy-agent/gatekeeper/pkg/version.Version=$(VERSION) \
-	-X github.com/open-policy-agent/gatekeeper/pkg/version.Vcs=$(BUILD_COMMIT) \
-	-X github.com/open-policy-agent/gatekeeper/pkg/version.Timestamp=$(BUILD_TIMESTAMP) \
-	-X github.com/open-policy-agent/gatekeeper/pkg/version.Hostname=$(BUILD_HOSTNAME) \
 	-X main.frameworksVersion=$(FRAMEWORKS_VERSION) \
 	-X main.opaVersion=$(OPA_VERSION)"
 

gator.Dockerfile

@@ -18,10 +18,8 @@ ENV GO111MODULE=on \
     GOARCH=${TARGETARCH} \
     GOARM=${TARGETVARIANT}
 
-COPY . /tmp/gatekeeper
-
-WORKDIR /tmp/gatekeeper/cmd/gator
-
+COPY . /go/src/github.com/open-policy-agent/gatekeeper
+WORKDIR /go/src/github.com/open-policy-agent/gatekeeper/cmd/gator
 RUN go build -mod vendor -a -ldflags "${LDFLAGS:--X github.com/open-policy-agent/gatekeeper/pkg/version.Version=latest -X main.frameworksVersion=latest -X main.opaVersion=latest}" -o /gator
 
 FROM --platform=$BUILDPLATFORM $BASEIMAGE as build

pkg/version/version.go

@@ -3,18 +3,32 @@ package version
 import (
 	"fmt"
 	"runtime"
+	"runtime/debug"
 )
 
-// Vcs is is the commit hash for the binary build.
-var Vcs string
-
-// Timestamp is the date for the binary build.
-var Timestamp string
-
 // Version is the gatekeeper version.
 var Version string
 
-// GetUserAgent returns a user agent of the format: gatekeeper/<version> (<goos>/<goarch>) <vcs>/<timestamp>.
+// GetUserAgent returns a user agent of the format: gatekeeper/<version> (<goos>/<goarch>) <vcsrevision><-vcsdirty>/<vcstimestamp>.
 func GetUserAgent() string {
-	return fmt.Sprintf("gatekeeper/%s (%s/%s) %s/%s", Version, runtime.GOOS, runtime.GOARCH, Vcs, Timestamp)
+	vcsrevision := "unknown"
+	vcstimestamp := "unknown"
+	vcsdirty := ""
+
+	if info, ok := debug.ReadBuildInfo(); ok {
+		for _, v := range info.Settings {
+			switch v.Key {
+			case "vcs.revision":
+				vcsrevision = v.Value
+			case "vcs.modified":
+				if v.Value == "true" {
+					vcsdirty = "-dirty"
+				}
+			case "vcs.time":
+				vcstimestamp = v.Value
+			}
+		}
+	}
+
+	return fmt.Sprintf("gatekeeper/%s (%s/%s) %s%s/%s", Version, runtime.GOOS, runtime.GOARCH, vcsrevision, vcsdirty, vcstimestamp)
 }