feat(cfapi): include origin-ca-issuer version

The team operating the Origin CA have requested this issuer include
version information in the User-Agent to aid in debugging issues on
their side and understand the rate at which updates to the issuer have
been adopted.

Introduces an internal "version" package where the binary version is
set via LDFLAGS. Starting with Go 1.24 this information will be embedded
into the binary's module, which can be queried instead.

Makefile

@@ -28,7 +28,7 @@ ifeq (${KERNEL},Linux)
 	GOFLAGS ?= -buildmode=pie
 endif
 
-GO_LDFLAGS += -w -s -X main.version=${VERSION}
+GO_LDFLAGS += -w -s -X github.com/cloudflare/origin-ca-issuer/internal/version.Version=${VERSION}
 GOFLAGS += -v
 
 export CGO_ENABLED

internal/cfapi/cfapi.go

@@ -8,6 +8,8 @@ import (
 	"net/http"
 	"net/url"
 	"time"
+
+	"github.com/cloudflare/origin-ca-issuer/internal/version"
 )
 
 type Interface interface {
@@ -121,7 +123,7 @@ func (c *Client) Sign(ctx context.Context, req *SignRequest) (*SignResponse, err
 		return nil, err
 	}
 
-	r.Header.Add("User-Agent", "github.com/cloudflare/origin-ca-issuer")
+	r.Header.Add("User-Agent", "origin-ca-issuer/"+version.Version)
 
 	if c.serviceKey != nil {
 		r.Header.Add("X-Auth-User-Service-Key", string(c.serviceKey))

internal/version/version.go

@@ -0,0 +1,3 @@
+package version
+
+var Version = "0.0.0"

pkgs/controllers/testdata/database-failure.yaml

@@ -16,7 +16,7 @@ interactions:
           form: {}
           headers:
               User-Agent:
-                  - github.com/cloudflare/origin-ca-issuer
+                  - origin-ca-issuer/0.0.0
               X-Auth-User-Service-Key:
                   - djEuMC0weDAwQkFCMTBD
           url: https://api.cloudflare.com/client/v4/certificates

pkgs/controllers/testdata/working.yaml

@@ -16,7 +16,7 @@ interactions:
       form: {}
       headers:
         User-Agent:
-          - github.com/cloudflare/origin-ca-issuer
+          - origin-ca-issuer/0.0.0
         X-Auth-User-Service-Key:
           - djEuMC0weDAwQkFCMTBD
       url: https://api.cloudflare.com/client/v4/certificates
@@ -62,7 +62,7 @@ interactions:
       form: {}
       headers:
         User-Agent:
-          - github.com/cloudflare/origin-ca-issuer
+          - origin-ca-issuer/0.0.0
         Authorization:
           - Bearer api-token
       url: https://api.cloudflare.com/client/v4/certificates