Each VM's firecracker now runs inside a per-VM chroot dropped to the registered owner UID via firecracker-jailer. Closes the broad ambient- sudo escalation surface that survived Phase A: the helper still needs caps for tap/bridge/dm/loop/iptables, but the VMM itself no longer runs as root in the host root filesystem. The host helper stages each chroot up front: hard-links the kernel and (optional) initrd, mknods block-device drives + /dev/vhost-vsock, copies in the firecracker binary (jailer opens it O_RDWR so a ro bind fails with EROFS), and bind-mounts /usr/lib + /lib trees read-only so the dynamic linker can resolve. Self-binds the chroot first so the findmnt-guarded cleanup can recurse safely. AF_UNIX sun_path is 108 bytes; the chroot path easily blows past that. Daemon-side launch pre-symlinks the short request socket path to the long chroot socket before Machine.Start so the SDK's poll/connect sees the short path while the kernel resolves to the chroot socket. --new-pid-ns is intentionally disabled — jailer's PID-namespace fork makes the SDK see the parent exit and tear the API socket down too early. CapabilityBoundingSet for the helper expands to add CAP_FOWNER, CAP_KILL, CAP_MKNOD, CAP_SETGID, CAP_SETUID, CAP_SYS_CHROOT alongside the existing CAP_CHOWN/CAP_DAC_OVERRIDE/CAP_NET_ADMIN/CAP_NET_RAW/ CAP_SYS_ADMIN. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
215 lines
6.3 KiB
Go
215 lines
6.3 KiB
Go
package cli
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import (
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"context"
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"errors"
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"os"
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"path/filepath"
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"strings"
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"testing"
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"banger/internal/api"
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"banger/internal/installmeta"
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)
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func TestEnsureDaemonRequiresSystemInstallWhenMetadataMissing(t *testing.T) {
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t.Setenv("XDG_CONFIG_HOME", filepath.Join(t.TempDir(), "config"))
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t.Setenv("XDG_STATE_HOME", filepath.Join(t.TempDir(), "state"))
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t.Setenv("XDG_CACHE_HOME", filepath.Join(t.TempDir(), "cache"))
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t.Setenv("XDG_RUNTIME_DIR", filepath.Join(t.TempDir(), "run"))
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restoreLoad := loadInstallMetadata
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restoreUID := currentUID
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t.Cleanup(func() {
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loadInstallMetadata = restoreLoad
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currentUID = restoreUID
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})
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loadInstallMetadata = func() (installmeta.Metadata, error) {
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return installmeta.Metadata{}, os.ErrNotExist
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}
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currentUID = os.Getuid
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d := defaultDeps()
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d.daemonPing = func(context.Context, string) (api.PingResult, error) {
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return api.PingResult{}, errors.New("dial unix /run/banger/bangerd.sock: no such file")
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}
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_, _, err := d.ensureDaemon(context.Background())
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if err == nil || !strings.Contains(err.Error(), "sudo banger system install") {
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t.Fatalf("ensureDaemon error = %v, want install guidance", err)
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}
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}
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func TestEnsureDaemonSuggestsRestartWhenInstalledButUnavailable(t *testing.T) {
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t.Setenv("XDG_CONFIG_HOME", filepath.Join(t.TempDir(), "config"))
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t.Setenv("XDG_STATE_HOME", filepath.Join(t.TempDir(), "state"))
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t.Setenv("XDG_CACHE_HOME", filepath.Join(t.TempDir(), "cache"))
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t.Setenv("XDG_RUNTIME_DIR", filepath.Join(t.TempDir(), "run"))
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restoreLoad := loadInstallMetadata
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restoreUID := currentUID
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t.Cleanup(func() {
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loadInstallMetadata = restoreLoad
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currentUID = restoreUID
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})
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loadInstallMetadata = func() (installmeta.Metadata, error) {
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return installmeta.Metadata{
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OwnerUser: "tester",
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OwnerUID: os.Getuid(),
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OwnerGID: os.Getgid(),
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OwnerHome: t.TempDir(),
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}, nil
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}
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currentUID = os.Getuid
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d := defaultDeps()
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d.daemonPing = func(context.Context, string) (api.PingResult, error) {
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return api.PingResult{}, errors.New("dial unix /run/banger/bangerd.sock: connection refused")
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}
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_, _, err := d.ensureDaemon(context.Background())
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if err == nil || !strings.Contains(err.Error(), "sudo banger system restart") {
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t.Fatalf("ensureDaemon error = %v, want restart guidance", err)
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}
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}
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func TestEnsureDaemonRejectsNonOwnerUser(t *testing.T) {
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restoreLoad := loadInstallMetadata
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restoreUID := currentUID
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t.Cleanup(func() {
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loadInstallMetadata = restoreLoad
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currentUID = restoreUID
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})
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loadInstallMetadata = func() (installmeta.Metadata, error) {
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return installmeta.Metadata{
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OwnerUser: "alice",
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OwnerUID: os.Getuid() + 1,
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OwnerGID: os.Getgid(),
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OwnerHome: t.TempDir(),
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}, nil
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}
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currentUID = os.Getuid
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d := defaultDeps()
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d.daemonPing = func(context.Context, string) (api.PingResult, error) {
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t.Fatal("daemonPing should not be called for a non-owner user")
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return api.PingResult{}, nil
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}
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_, _, err := d.ensureDaemon(context.Background())
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if err == nil || !strings.Contains(err.Error(), "installed for alice") {
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t.Fatalf("ensureDaemon error = %v, want owner mismatch guidance", err)
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}
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}
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func TestSystemSubcommandFlagsAreScoped(t *testing.T) {
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root := NewBangerCommand()
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systemCmd, _, err := root.Find([]string{"system"})
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if err != nil {
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t.Fatalf("find system: %v", err)
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}
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installCmd, _, err := systemCmd.Find([]string{"install"})
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if err != nil {
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t.Fatalf("find system install: %v", err)
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}
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uninstallCmd, _, err := systemCmd.Find([]string{"uninstall"})
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if err != nil {
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t.Fatalf("find system uninstall: %v", err)
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}
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if installCmd.Flags().Lookup("owner") == nil {
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t.Fatal("system install is missing --owner")
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}
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if uninstallCmd.Flags().Lookup("purge") == nil {
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t.Fatal("system uninstall is missing --purge")
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}
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}
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func TestRenderSystemdUnitIncludesHardeningDirectives(t *testing.T) {
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unit := renderSystemdUnit(installmeta.Metadata{
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OwnerUser: "alice",
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OwnerUID: 1000,
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OwnerGID: 1000,
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OwnerHome: "/home/alice/dev home",
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})
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for _, want := range []string{
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"ExecStart=/usr/local/bin/bangerd --system",
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"User=alice",
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"Wants=network-online.target bangerd-root.service",
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"After=bangerd-root.service",
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"Requires=bangerd-root.service",
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"UMask=0077",
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"Environment=TMPDIR=/run/banger",
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"NoNewPrivileges=yes",
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"PrivateMounts=yes",
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"ProtectSystem=strict",
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"ProtectHome=read-only",
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"ProtectControlGroups=yes",
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"ProtectKernelLogs=yes",
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"ProtectKernelModules=yes",
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"ProtectClock=yes",
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"ProtectHostname=yes",
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"RestrictSUIDSGID=yes",
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"LockPersonality=yes",
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"SystemCallArchitectures=native",
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"RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6 AF_NETLINK AF_VSOCK",
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"StateDirectory=banger",
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"StateDirectoryMode=0700",
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"CacheDirectory=banger",
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"CacheDirectoryMode=0700",
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"RuntimeDirectory=banger",
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"RuntimeDirectoryMode=0700",
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`ReadOnlyPaths="/home/alice/dev home"`,
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} {
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if !strings.Contains(unit, want) {
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t.Fatalf("unit = %q, want %q", unit, want)
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}
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}
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}
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func TestRenderRootHelperSystemdUnitIncludesRequiredCapabilities(t *testing.T) {
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unit := renderRootHelperSystemdUnit()
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for _, want := range []string{
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"ExecStart=/usr/local/bin/bangerd --root-helper",
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"Environment=TMPDIR=/run/banger-root",
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"NoNewPrivileges=yes",
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"PrivateTmp=yes",
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"PrivateMounts=yes",
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"ProtectSystem=strict",
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"ProtectHome=yes",
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"RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6 AF_NETLINK AF_VSOCK",
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"CapabilityBoundingSet=CAP_CHOWN CAP_DAC_OVERRIDE CAP_FOWNER CAP_KILL CAP_MKNOD CAP_NET_ADMIN CAP_NET_RAW CAP_SETGID CAP_SETUID CAP_SYS_ADMIN CAP_SYS_CHROOT",
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"ReadWritePaths=/var/lib/banger",
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"RuntimeDirectory=banger-root",
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"RuntimeDirectoryMode=0711",
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} {
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if !strings.Contains(unit, want) {
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t.Fatalf("unit = %q, want %q", unit, want)
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}
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}
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}
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func TestRenderSystemdUnitsIncludeOptionalCoverageEnv(t *testing.T) {
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t.Setenv(systemCoverDirEnv, "/var/lib/banger")
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t.Setenv(rootCoverDirEnv, "/var/lib/banger")
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userUnit := renderSystemdUnit(installmeta.Metadata{
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OwnerUser: "alice",
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OwnerUID: 1000,
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OwnerGID: 1000,
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OwnerHome: "/home/alice",
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})
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if !strings.Contains(userUnit, `Environment=GOCOVERDIR="/var/lib/banger"`) {
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t.Fatalf("user unit = %q, want GOCOVERDIR env", userUnit)
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}
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rootUnit := renderRootHelperSystemdUnit()
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if !strings.Contains(rootUnit, `Environment=GOCOVERDIR="/var/lib/banger"`) {
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t.Fatalf("root unit = %q, want GOCOVERDIR env", rootUnit)
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}
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}
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