Replace commit.txt with ldflags value

Author: DavidS-ovm

.github/workflows/test-build.yml

@@ -35,7 +35,6 @@ jobs:
       - name: Go Generate
         run: |
           go generate ./...
-          cat tracing/commit.txt
 
       - name: Validate Docs Data
         run: |

.gitignore

@@ -7,6 +7,5 @@ vendor
 Gopkg.lock
 build/compiled
 .idea
-commit.txt
 .envrc
 .golangci.yml

build/package/Dockerfile

@@ -23,7 +23,7 @@ COPY . .
 RUN --mount=type=cache,target=/go/pkg \
     --mount=type=cache,target=/root/.cache/go-build \
     go generate ./... \
-    && GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -ldflags="-s -w" -trimpath -o source main.go
+    && GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -ldflags="-s -w -X github.com/overmindtech/aws-source/tracing.ServiceVersion=$(git describe --tags --exact-match 2>/dev/null || git rev-parse --short HEAD)" -trimpath -o source main.go
 
 FROM alpine:3.21
 WORKDIR /

tracing/tracing.go

@@ -22,9 +22,15 @@ import (
 	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
 )
 
-//go:generate sh -c "echo -n $(git describe --tags --exact-match 2>/dev/null || git rev-parse --short HEAD) > commit.txt"
-//go:embed commit.txt
-var ServiceVersion string
+// ServiceVersion is the version of the service. This will be overridden by the
+// build system, using:
+// go build -ldflags "-X github.com/overmindtech/api-server/tracing.ServiceVersion=$(git describe --tags --exact-match 2>/dev/null || git rev-parse --short HEAD)" -o your-app
+//
+// This allows our change detection workflow to work correctly. If we were
+// embedding the version here each time we would always produce a slightly
+// different compiled binary, and therefore it would look like there was a
+// change each time
+var ServiceVersion = "dev"
 
 func tracingResource() *resource.Resource {
 	// Identify your application using resource detection