Stamp the tag or short commit in a plain docker build (closes #166)

.dockerignore now lets .git into the build context, without
.git/config, which can hold a remote URL with a credential. ARG VERSION
has no default: given none, the build stage takes the version from
git describe --tags --always, and fails if the context carries .git
and no version comes out. pixad now logs its name, version and
architecture as its first log line, through the existing
Logger.Identify, which nothing called.

Model: opus-5-5

.dockerignore

@@ -1,4 +1,8 @@
-.git
+# .git is sent without its config. Without a VERSION build argument the
+# stage that compiles runs `git describe --tags --always` on .git, which
+# does not need .git/config; that file can hold a credential, such as a
+# password in a remote URL or the token the CI checkout step stores there.
+.git/config
 .gitignore
 .DS_Store
 .env*

CONVENTIONS.md

@@ -112,15 +112,13 @@ import (
 )
 
 var (
-    Appname   string = "CHANGEME"
+    Appname string = "CHANGEME"
-    Version   string
+    Version string
-    Buildarch string
 )
 
 func main() {
     globals.Appname = Appname
     globals.Version = Version
-    globals.Buildarch = Buildarch
 
     fx.New(
         fx.Provide(
@@ -859,7 +857,7 @@ func (l *Logger) Identify() {
     l.log.Info("starting",
         "appname", l.params.Globals.Appname,
         "version", l.params.Globals.Version,
-        "buildarch", l.params.Globals.Buildarch,
+        "arch", runtime.GOARCH,
     )
 }
 ```
@@ -979,23 +977,20 @@ import "go.uber.org/fx"
 
 // Package-level variables (set from main)
 var (
-    Appname   string
+    Appname string
-    Version   string
+    Version string
-    Buildarch string
 )
 
 // Struct for DI
 type Globals struct {
-    Appname   string
+    Appname string
-    Version   string
+    Version string
-    Buildarch string
 }
 
 func New(lc fx.Lifecycle) (*Globals, error) {
     n := &Globals{
-        Appname:   Appname,
+        Appname: Appname,
-        Buildarch: Buildarch,
+        Version: Version,
-        Version:   Version,
     }
     return n, nil
 }
@@ -1006,15 +1001,13 @@ func New(lc fx.Lifecycle) (*Globals, error) {
 ```go
 // cmd/httpd/main.go
 var (
-    Appname   string = "CHANGEME"  // Default, overridden by build
+    Appname string = "CHANGEME"  // Default, overridden by build
-    Version   string               // Set at build time
+    Version string               // Set at build time
-    Buildarch string               // Set at build time
 )
 
 func main() {
     globals.Appname = Appname
     globals.Version = Version
-    globals.Buildarch = Buildarch
     // ...
 }
 ```
@@ -1025,10 +1018,9 @@ Use ldflags to inject version information at build time:
 
 ```makefile
 VERSION := $(shell git describe --tags --always)
-BUILDARCH := $(shell go env GOARCH)
 
 build:
-    go build -ldflags "-X main.Version=$(VERSION) -X main.Buildarch=$(BUILDARCH)" ./cmd/httpd
+    go build -ldflags "-X main.Version=$(VERSION)" ./cmd/httpd
 ```
 
 ---

Dockerfile

@@ -43,13 +43,24 @@ COPY . .
 RUN make test
 
 # VERSION is declared here, not earlier: a new value reruns only the
-# build, not script/bootstrap or the tests. CGO stays enabled for
+# build, not script/bootstrap or the tests. Given none, the version is
-# govips; -trimpath keeps build paths out of the binary, and -s -w
+# `git describe --tags --always` of the .git in the build context (git
-# leave out the symbol table and debug information.
+# comes from script/bootstrap): the tag on a tagged commit, tag-N-gHASH
-ARG VERSION=dev
+# after one, the short commit when no tag is reachable. A context that
-RUN CGO_ENABLED=1 GOTOOLCHAIN=auto go build -trimpath \
+# carries .git and still yields no version fails the build; one without
-    -ldflags "-s -w -X main.Version=${VERSION}" \
+# .git, as from a source tarball, stamps an empty version. CGO stays
-    -o /pixad ./cmd/pixad
+# enabled for govips; -trimpath keeps build paths out of the binary, and
+# -s -w leave out the symbol table and debug information.
+ARG VERSION
+RUN version="${VERSION:-$(git describe --tags --always)}"; \
+    if [ -e .git ] && { [ -z "$version" ] || [ "$version" = dev ] || \
+        [ "$version" = unknown ]; }; then \
+        echo "the build context carries .git but yields no version" >&2; \
+        exit 1; \
+    fi; \
+    CGO_ENABLED=1 GOTOOLCHAIN=auto go build -trimpath \
+        -ldflags "-s -w -X main.Version=${version}" \
+        -o /pixad ./cmd/pixad
 
 # Runtime stage
 # alpine:3.21, 2026-02-25

TODO.md

@@ -29,6 +29,13 @@ P2: security: referer blacklist
 
 # Completed Steps
 
+- 2026-10-02 a plain `docker build .` stamps the tag or short commit, not
+  `dev` (closes #166): `.dockerignore` lets `.git` into the build context,
+  without `.git/config`; with no `VERSION` build argument the `Dockerfile`
+  takes the version from `git describe --tags --always`, and fails the build if
+  the context carries `.git` and no version comes out; `ARG VERSION` has no
+  default; pixad logs its version, with its name and architecture, as its first
+  log line at startup.
 - 2026-09-29 the container makes `/var/lib/pixa` usable by itself (closes
   #159): `deploy/docker-entrypoint.sh` creates the directory if it is missing,
   gives the directory and everything in it to `pixad` when the directory or one

cmd/pixad/main.go

@@ -56,6 +56,9 @@ func run(_ *cobra.Command, _ []string) {
 			middleware.New,
 			healthcheck.New,
 		),
-		fx.Invoke(func(*server.Server) {}),
+		fx.Invoke(
+			func(log *logger.Logger) { log.Identify() },
+			func(*server.Server) {},
+		),
 	).Run()
 }