docker: a plain docker build . stamps the git version (closes #210)

A plain `docker build .`, which is how upaas builds, stamped `dev`:
`.dockerignore` left out `.git` and the builder declared
`ARG VERSION=dev`. `.dockerignore` now sends `.git` and lists no tracked
file, which git in the build would count as deleted and mark `-dirty`.
`ARG VERSION` has no default. The Makefile takes `VERSION` from the
environment with `?=`, so a build arg still wins (`script/docker` keeps
passing one); otherwise `git describe` runs in the builder. A new
`make version` prints the version, and the builder fails when the
context carries `.git` and it comes out empty, `dev` or `unknown`.

Model: opus-5-5

.dockerignore

@@ -1,9 +1,6 @@
-# .git is sent, without its config: the builder stage derives the version it
+# .git is sent: the builder stage derives the version it stamps into the
-# stamps into the binary from it, and `git describe` does not need the config,
+# binary from it. No tracked file may be listed here: git in the build
-# which can hold a credential (a password in the remote URL, a CI token). No
+# would see it as deleted and mark the version -dirty, and an excluded .md
-# tracked file may be listed here: git in the build would see it as deleted
+# would silently drop out of the prettier check in Dockerfile.fmt.
-# and mark the version -dirty, and an excluded .md would silently drop out of
-# the prettier check in Dockerfile.fmt.
-.git/config
 bin/
 node_modules/

Dockerfile

@@ -37,17 +37,16 @@ COPY . .
 RUN make test
 
 # Version stamped into the binary: the VERSION build arg when one is
-# given and not empty (script/docker passes one), otherwise what
+# given (script/docker passes one), otherwise what `git describe` says of
-# `git describe` says of the .git in the build context, so a plain
+# the .git in the build context, so a plain `docker build .` of a clone
-# `docker build .` of a clone stamps its tag or short commit. The build
+# stamps its tag or short commit. The build arg reaches make through the
-# arg reaches make through the environment.
+# environment.
 ARG VERSION
 
-# A context that carries .git, as a directory or as a file, must yield a
+# A context that carries .git must yield a real version: one that is
-# real version: one that is empty, `dev` or `unknown` cannot be traced
+# empty, `dev` or `unknown` cannot be traced back to a commit.
-# back to a commit.
 RUN version="$(make version)"; \
-    if [ -e .git ]; then \
+    if [ -d .git ]; then \
         case "$version" in \
             "" | dev | unknown) \
                 echo "version is \"$version\" although the build context carries .git" >&2; \

Makefile

@@ -3,11 +3,8 @@
 BINARY := dnswatcher
 # VERSION given on the command line (`make build VERSION=...`) or in the
 # environment, which is how the Dockerfile's VERSION build arg arrives,
-# wins over what `git describe` says of this checkout. An empty one counts
+# wins over what `git describe` says of this checkout.
-# as not given; `override` is what replaces an empty command-line value.
+VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
-ifeq ($(VERSION),)
-override VERSION := $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
-endif
 LDFLAGS := -X main.Version=$(VERSION)
 
 # Standard targets are thin shims; the implementations live in script/

README.md

@@ -407,13 +407,6 @@ it watches. Instead, it performs full iterative resolution:
 4. **Authoritative query**: Queries all discovered authoritative nameservers
    directly for the requested records.
 
-In steps 2 and 3 the servers are asked one at a time in a random order, chosen
-anew each time, so no one root server gets every first query. A server that does
-not reply, refuses the query, or gives an error reply such as SERVFAIL or a
-referral that leads no closer to the name is passed over for the next one. When
-a referral names a zone's nameservers without their addresses, the addresses of
-all of them are looked up, so that each can be asked.
-
 This approach ensures:
 
 - Independence from any upstream resolver's cache or filtering.
@@ -587,19 +580,17 @@ make clean      # Remove build artifacts
 `make build` sets the version with `-ldflags "-X main.Version=..."`, taking it
 from `VERSION` when given on the command line (`make build VERSION=1.2.3`) or in
 the environment, otherwise from `git describe --tags --always --dirty`, and
-`dev` without git metadata. An empty `VERSION` counts as not given. The version
+`dev` without git metadata. The version appears in the startup log and in the
-appears in the startup log and in the health check response.
+health check response.
 
 The image takes it the same way, from the `.git` the build context carries, so a
 plain `docker build .` of a clone stamps the commit it was built from; a clone
-without tags, such as a shallow one, stamps the short commit. `.dockerignore`
+without tags, such as a shallow one, stamps the short commit. A
-sends `.git` without `.git/config`, which `git describe` does not need and which
+`--build-arg VERSION=...` takes precedence; `make docker` passes the version
-can hold a credential. A non-empty `--build-arg VERSION=...` takes precedence;
+`git describe` gives on the host. The build fails when the context carries
-`make docker` passes the version `git describe` gives on the host. The build
+`.git` and the version comes out empty, `dev` or `unknown`. `.dockerignore` must
-fails when the context carries `.git`, as a directory or as a file, and the
+list no tracked file: git in the build would see it as deleted and mark the
-version comes out empty, `dev` or `unknown`. `.dockerignore` must list no
+version `-dirty`.
-tracked file: git in the build would see it as deleted and mark the version
-`-dirty`.
 
 ---
 

TODO.md

@@ -21,8 +21,6 @@ trial run of the finished image: https://git.eeqj.de/sneak/dnswatcher/issues/149
 
 - 2026-10-02: a plain `docker build .` of a clone stamps its tag or short
   commit, not `dev`: the build context now carries `.git` (closes #210).
-- 2026-10-02: the resolver tries root servers, and every other server list it
-  walks, in a random order each time, not always from the top (closes #138).
 - 2026-10-02: a name listed more than once in `DNSWATCHER_TARGETS`, in any
   letter case or with a trailing dot, is watched once (closes #207).
 - 2026-10-01: README checked against the code and corrected: metrics, CORS,
@@ -135,4 +133,5 @@ trial run of the finished image: https://git.eeqj.de/sneak/dnswatcher/issues/149
 
 - 1.0 readiness: run it with a real config and read the logs:
   https://git.eeqj.de/sneak/dnswatcher/issues/66
+- fixed root server order: https://git.eeqj.de/sneak/dnswatcher/issues/138
 - review toward 1.0: https://git.eeqj.de/sneak/dnswatcher/issues/144

internal/livednstest/livednstest.go

@@ -9,11 +9,11 @@
 //
 //  1. Bounded concurrency. Tests run in parallel and the build hosts
 //     have many cores, so without a limit every test starts its own
-//     iterative resolution at the same instant and they all send their
+//     iterative resolution at the same instant and they all hit the
-//     first queries to the root servers within a few milliseconds of
+//     first root server within a few milliseconds of each other. Root
-//     each other. Root servers rate-limit that, which shows up as a
+//     servers rate-limit that, which shows up as a different arbitrary
-//     different arbitrary subset of tests failing on each run. Run caps
+//     subset of tests failing on each run. Run caps how many live
-//     how many live operations are in flight at once in one test binary.
+//     operations are in flight at once in one test binary.
 //
 //  2. Retry with exponential backoff. Each live operation gets several
 //     attempts with its own timeout. An attempt is retried when it

internal/resolver/export_test.go

@@ -36,24 +36,3 @@ func (r *Resolver) QueryEachNS(
 ) (map[string]*NameserverResponse, error) {
 	return r.queryEachNS(ctx, nameservers, hostname)
 }
-
-// ResolveNSIPs exports resolveNSIPs for testing.
-func (r *Resolver) ResolveNSIPs(
-	ctx context.Context,
-	nsNames []string,
-) []string {
-	return r.resolveNSIPs(ctx, nsNames)
-}
-
-// RootServerList exports rootServerList for testing.
-func RootServerList() []string {
-	return rootServerList()
-}
-
-// Shuffled exports shuffled for testing.
-func Shuffled(
-	servers []string,
-	shuffle func(n int, swap func(i, j int)),
-) []string {
-	return shuffled(servers, shuffle)
-}

internal/resolver/iterative.go

@@ -4,9 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"math/rand/v2"
 	"net"
-	"slices"
 	"sort"
 	"strings"
 	"time"
@@ -261,25 +259,9 @@ func (r *Resolver) followDelegation(
 	return nil, ErrNoNameservers
 }
 
-// shuffled returns a copy of servers in the order shuffle puts them
+// queryServers asks servers, the servers of zone, about name until one
-// in. The resolver passes rand.Shuffle, so each time it walks a list of
+// gives a usable reply. A server that times out, refuses or gives a
-// servers it starts at a random one, and no one server gets every
+// reply that is not usable is passed over for the next.
-// first query.
-func shuffled(
-	servers []string,
-	shuffle func(n int, swap func(i, j int)),
-) []string {
-	order := slices.Clone(servers)
-	shuffle(len(order), func(i, j int) {
-		order[i], order[j] = order[j], order[i]
-	})
-
-	return order
-}
-
-// queryServers asks servers, the servers of zone, about name in a random
-// order until one gives a usable reply. A server that times out, refuses
-// or gives a reply that is not usable is passed over for the next.
 func (r *Resolver) queryServers(
 	ctx context.Context,
 	servers []string,
@@ -289,7 +271,7 @@ func (r *Resolver) queryServers(
 ) (*dns.Msg, error) {
 	var lastErr error
 
-	for _, ip := range shuffled(servers, rand.Shuffle) {
+	for _, ip := range servers {
 		if checkCtx(ctx) != nil {
 			return nil, ErrContextCanceled
 		}
@@ -358,10 +340,6 @@ func nsSetFrom(resp *dns.Msg, domain string) []string {
 	return extractNSSet(resp.Answer)
 }
 
-// resolveNSIPs returns the addresses of every nameserver in nsNames
-// whose name resolves, for a referral that carries none. The walk can
-// then go on to the zone's other nameservers when one gives no usable
-// reply.
 func (r *Resolver) resolveNSIPs(
 	ctx context.Context,
 	nsNames []string,
@@ -373,6 +351,10 @@ func (r *Resolver) resolveNSIPs(
 		if err == nil {
 			ips = append(ips, resolved...)
 		}
+
+		if len(ips) > 0 {
+			break
+		}
 	}
 
 	return ips

internal/resolver/iterative_test.go

@@ -1,8 +1,6 @@
 package resolver_test
 
 import (
-	"math/rand/v2"
-	"slices"
 	"testing"
 
 	"github.com/miekg/dns"
@@ -237,30 +235,3 @@ func TestExtractRecordValue_LetterCase(t *testing.T) {
 		})
 	}
 }
-
-// TestShuffled shuffles the root servers with many seeds. Every order
-// must hold each root server once, so each is tried before a
-// resolution fails; each root server must come first for some seed, so
-// no one root server gets every first query; and the list passed in
-// must be left as it was.
-func TestShuffled(t *testing.T) {
-	t.Parallel()
-
-	const seeds = 1000
-
-	roots := resolver.RootServerList()
-	before := slices.Clone(roots)
-	first := make(map[string]bool)
-
-	for seed := range uint64(seeds) {
-		rng := rand.New(rand.NewPCG(seed, 0)) //nolint:gosec // seeded on purpose
-		order := resolver.Shuffled(roots, rng.Shuffle)
-
-		assert.ElementsMatch(t, roots, order)
-
-		first[order[0]] = true
-	}
-
-	assert.Len(t, first, len(roots))
-	assert.Equal(t, before, roots)
-}

internal/resolver/livedns_test.go

@@ -383,37 +383,3 @@ func liveResolveIPsAllowingEmpty(
 
 	return out
 }
-
-// liveResolveNSIPs looks up the addresses of the nameservers named
-// names, retrying until there are at least atLeast of them: a name
-// whose lookup got no reply is left out of the result, not an error.
-func liveResolveNSIPs(
-	t *testing.T,
-	r *resolver.Resolver,
-	names []string,
-	atLeast int,
-) []string {
-	t.Helper()
-
-	var out []string
-
-	livednstest.Retry(
-		t,
-		"ResolveNSIPs("+strings.Join(names, ", ")+")",
-		func(ctx context.Context) error {
-			ips := r.ResolveNSIPs(ctx, names)
-			if len(ips) < atLeast {
-				return fmt.Errorf(
-					"%w: %d addresses, expected at least %d",
-					livednstest.ErrNoAnswer, len(ips), atLeast,
-				)
-			}
-
-			out = ips
-
-			return nil
-		},
-	)
-
-	return out
-}

internal/resolver/resolver_test.go

@@ -139,28 +139,6 @@ func TestFindAuthoritativeNameservers_CloudflareDomain(
 	}
 }
 
-// TestResolveNSIPs_EveryNameserver looks up the addresses of two of
-// google.com's nameservers together, as the walk does when a referral
-// names a zone's nameservers without their addresses, and compares them
-// with each looked up alone. Together they must give the addresses of
-// both, not only of the first that resolves, so that when one gives no
-// usable reply the walk goes on to the other.
-func TestResolveNSIPs_EveryNameserver(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	names := []string{"ns3.google.com.", "ns4.google.com."}
-	want := make([]string, 0, len(names))
-
-	for _, name := range names {
-		want = append(want, liveResolveNSIPs(t, r, []string{name}, 1)...)
-	}
-
-	got := liveResolveNSIPs(t, r, names, len(want))
-
-	assert.ElementsMatch(t, want, got)
-}
-
 // ----------------------------------------------------------------
 // QueryNameserver tests
 // ----------------------------------------------------------------