[client] Categorize privileged tests behind a build tag and run them in Docker (#6425)

* [client] categorize root/system-mutating tests behind a privileged build tag

Tests that need root or mutate host state (nftables/iptables/DNS, TUN/WireGuard
interfaces, routes, eBPF, SSH/service install) are now gated behind a
//go:build privileged tag. The default `go test ./client/...` runs as a non-root
user with no sudo and leaves host networking untouched; mixed files were split so
pure-logic tests stay in the default suite.

A self-hosting ory/dockertest/v4 harness (client/testutil/privileged) runs the
privileged suite inside a --privileged --cap-add=NET_ADMIN container via
`make test-privileged`; a DOCKER_CI=true guard skips the spawn when already inside
the container. Added `make test-unit` for the host-safe run.

* [client] add PRIV_RUN/PRIV_PKGS filters to the privileged test harness

The dockertest harness now reads two optional env vars when building the
in-container `go test` command: PRIV_RUN adds a -run test-name filter and
PRIV_PKGS overrides the package list. Both empty reproduce the full privileged
suite, so CI and `make test-privileged` behave as before. Lets a developer run a
single privileged test in the container, e.g.:

  PRIV_RUN=TestNftablesManager PRIV_PKGS=./client/firewall/nftables/... make test-privileged

* [client] fix unused-helper lint after the privileged test split

Splitting privileged tests into *_privileged_test.go left their shared helpers in
the untagged files, so in the default (no-tag) build they had no callers and
golangci-lint flagged them as unused.

Moved the privileged-only helpers into the privileged files next to their callers
(generateDummyHandler; createEngine/startSignal/startManagement/getConnectedPeers/
getPeers + kaep/kasp; (*mockDaemon).setJWTToken). Annotated the shared routing-test
fixtures that must stay untagged for cross-platform compilation with //nolint:unused
(systemops_bsd expected* vars, ensureIPv6DefaultRoute on bsd/windows,
loopbackIfaceWindows), matching the existing linux variant.

* [client] fix privileged test CI failures and run the harness on macOS

The host-safe unit run dropped sudo but two privileged test groups were
never tagged, and the Docker privileged job silently never ran the suite:

- Gate the ssh/server PrivilegeDropper command-construction tests behind
  the privileged tag (they require root to target a different UID); split
  them into executor_unix_privileged_test.go.
- Tag sharedsock raw-socket tests privileged (need CAP_NET_RAW).
- Fix the Docker job command: nested single quotes around the build tags
  closed the sh -c wrapper early, dropping the go list package set and the
  privileged tag, so go test ran on the empty repo root. Use double quotes.

Make the self-hosting harness usable from a dev Mac:

- Build it on darwin as well as linux; it only drives Docker.
- Resolve the active docker context endpoint into DOCKER_HOST when the
  default /var/run/docker.sock is absent (Docker Desktop, Colima, OrbStack).
- Rename the misspelled containerGoModache constant to containerGoModCache.

* Update client/internal/engine_privileged_test.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Update client/internal/routemanager/systemops/systemops_linux_test.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Update client/internal/routemanager/systemops/systemops_windows_test.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Update client/server/server_privileged_test.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* [ci] Run privileged-tagged tests on darwin, windows and freebsd

The privileged build tag split moved root/system-mutating tests behind
//go:build privileged, but only the linux docker job was given the tag.
The native darwin (sudo), windows (PsExec64 -s) and freebsd VM runners
already have the required privileges, so add the privileged tag there too
to keep CI running the same set of tests as before the split.

* [ci] Exclude dockertest harness from the darwin privileged run

The privileged tag now compiles client/testutil/privileged on darwin, whose
TestRunPrivilegedSuiteInDocker spawns a container the macOS runner has no
Docker for. Exclude the harness package from the darwin list, matching the
linux job, so the privileged tests run in place without a container spawn.

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

.github/workflows/golang-test-darwin.yml

@@ -45,7 +45,7 @@ jobs:
         run: git --no-pager diff --exit-code
 
       - name: Test
-        run: NETBIRD_STORE_ENGINE=${{ matrix.store }} CI=true go test -coverprofile=coverage.txt -tags=devcert -exec 'sudo --preserve-env=CI,NETBIRD_STORE_ENGINE' -timeout 5m -p 1 $(go list ./... | grep -v -e /management -e /signal -e /relay -e /proxy -e /combined)
+        run: NETBIRD_STORE_ENGINE=${{ matrix.store }} CI=true go test -coverprofile=coverage.txt -tags 'devcert privileged' -exec 'sudo --preserve-env=CI,NETBIRD_STORE_ENGINE' -timeout 5m -p 1 $(go list ./... | grep -v -e /management -e /signal -e /relay -e /proxy -e /combined -e /client/testutil/privileged)
 
       - name: Upload coverage reports to Codecov
         uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f #v7.0.0

.github/workflows/golang-test-freebsd.yml

@@ -48,14 +48,14 @@ jobs:
             export PATH=$PATH:/usr/local/go/bin:$HOME/go/bin
             time go build -o netbird client/main.go
             # check all component except management, since we do not support management server on freebsd
-            time go test -timeout 1m -failfast ./base62/...
+            time go test -tags privileged -timeout 1m -failfast ./base62/...
             # NOTE: without -p1 `client/internal/dns` will fail because of `listen udp4 :33100: bind: address already in use`
-            time go test -timeout 8m -failfast -v -p 1 ./client/...
-            time go test -timeout 1m -failfast ./dns/...
-            time go test -timeout 1m -failfast ./encryption/...
-            time go test -timeout 1m -failfast ./formatter/...
-            time go test -timeout 1m -failfast ./client/iface/...
-            time go test -timeout 1m -failfast ./route/...
-            time go test -timeout 1m -failfast ./sharedsock/...
-            time go test -timeout 1m -failfast ./util/...
-            time go test -timeout 1m -failfast ./version/...
+            time go test -tags privileged -timeout 8m -failfast -v -p 1 ./client/...
+            time go test -tags privileged -timeout 1m -failfast ./dns/...
+            time go test -tags privileged -timeout 1m -failfast ./encryption/...
+            time go test -tags privileged -timeout 1m -failfast ./formatter/...
+            time go test -tags privileged -timeout 1m -failfast ./client/iface/...
+            time go test -tags privileged -timeout 1m -failfast ./route/...
+            time go test -tags privileged -timeout 1m -failfast ./sharedsock/...
+            time go test -tags privileged -timeout 1m -failfast ./util/...
+            time go test -tags privileged -timeout 1m -failfast ./version/...

.github/workflows/golang-test-linux.yml

@@ -158,7 +158,7 @@ jobs:
         run: git --no-pager diff --exit-code
 
       - name: Test
-        run: CGO_ENABLED=1 GOARCH=${{ matrix.arch }} CI=true go test -coverprofile=coverage.txt -tags devcert -exec 'sudo' -timeout 10m -p 1 $(go list ./... | grep -v -e /management -e /signal -e /relay -e /proxy -e /combined)
+        run: CGO_ENABLED=1 GOARCH=${{ matrix.arch }} CI=true go test -coverprofile=coverage.txt -tags devcert -timeout 10m -p 1 $(go list ./... | grep -v -e /management -e /signal -e /relay -e /proxy -e /combined)
 
       - name: Upload coverage reports to Codecov
         if: matrix.arch == 'amd64'
@@ -229,7 +229,7 @@ jobs:
             sh -c ' \
               apk update; apk add --no-cache \
                 ca-certificates iptables ip6tables dbus dbus-dev libpcap-dev build-base; \
-              go test -buildvcs=false -tags devcert -v -timeout 10m -p 1 $(go list -buildvcs=false ./... | grep -v -e /management -e /signal -e /relay -e /proxy -e /combined -e /client/ui -e /upload-server)
+              go test -buildvcs=false -tags "devcert privileged" -v -timeout 10m -p 1 $(go list -buildvcs=false ./... | grep -v -e /management -e /signal -e /relay -e /proxy -e /combined -e /client/ui -e /upload-server -e /client/testutil/privileged)
             '
 
   test_relay:

.github/workflows/golang-test-windows.yml

@@ -68,7 +68,7 @@ jobs:
         run: |
           $packages = go list ./... | Where-Object { $_ -notmatch '/management' } | Where-Object { $_ -notmatch '/relay' } | Where-Object { $_ -notmatch '/signal' } | Where-Object { $_ -notmatch '/proxy' } | Where-Object { $_ -notmatch '/combined' }
           $goExe = "C:\hostedtoolcache\windows\go\${{ steps.go.outputs.go-version }}\x64\bin\go.exe"
-          $cmd = "$goExe test -tags=devcert -timeout 10m -p 1 $($packages -join ' ') > test-out.txt 2>&1"
+          $cmd = "$goExe test -tags `"devcert privileged`" -timeout 10m -p 1 $($packages -join ' ') > test-out.txt 2>&1"
           Set-Content -Path "${{ github.workspace }}\run-tests.cmd" -Value $cmd
 
       - name: test