sqlite: add a hidden --db-backend flag

Add a hidden flag to set the database backend and plumb it into
podman-info.  Further add a system test to make sure the flag and the
info output are working properly.

Note that the test may need to be changed once we settled on how
to test the sqlite backend in CI.

Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

cmd/podman/root.go

@@ -423,6 +423,9 @@ func rootFlags(cmd *cobra.Command, podmanConfig *entities.PodmanConfig) {
 		}
 		podmanConfig.Remote = true
 	} else {
+		// A *hidden* flag to change the database backend.
+		pFlags.StringVar(&podmanConfig.ContainersConf.Engine.DBBackend, "db-backend", podmanConfig.ContainersConfDefaultsRO.Engine.DBBackend, "Database backend to use")
+
 		cgroupManagerFlagName := "cgroup-manager"
 		pFlags.StringVar(&podmanConfig.ContainersConf.Engine.CgroupManager, cgroupManagerFlagName, podmanConfig.ContainersConfDefaultsRO.Engine.CgroupManager, "Cgroup manager to use (\"cgroupfs\"|\"systemd\")")
 		_ = cmd.RegisterFlagCompletionFunc(cgroupManagerFlagName, common.AutocompleteCgroupManager)
@@ -498,6 +501,7 @@ func rootFlags(cmd *cobra.Command, podmanConfig *entities.PodmanConfig) {
 		// Hide these flags for both ABI and Tunneling
 		for _, f := range []string{
 			"cpu-profile",
+			"db-backend",
 			"default-mounts-file",
 			"max-workers",
 			"memory-profile",

libpod/define/info.go

@@ -34,6 +34,7 @@ type HostInfo struct {
 	Conmon            *ConmonInfo      `json:"conmon"`
 	CPUs              int              `json:"cpus"`
 	CPUUtilization    *CPUUsage        `json:"cpuUtilization"`
+	DatabaseBackend   string           `json:"databaseBackend"`
 	Distribution      DistributionInfo `json:"distribution"`
 	EventLogger       string           `json:"eventLogger"`
 	Hostname          string           `json:"hostname"`

libpod/info.go

@@ -100,22 +100,23 @@ func (r *Runtime) hostInfo() (*define.HostInfo, error) {
 		return nil, err
 	}
 	info := define.HostInfo{
-		Arch:           runtime.GOARCH,
-		BuildahVersion: buildah.Version,
-		Linkmode:       linkmode.Linkmode(),
-		CPUs:           runtime.NumCPU(),
-		CPUUtilization: cpuUtil,
-		Distribution:   hostDistributionInfo,
-		LogDriver:      r.config.Containers.LogDriver,
-		EventLogger:    r.eventer.String(),
-		Hostname:       host,
-		Kernel:         kv,
-		MemFree:        mi.MemFree,
-		MemTotal:       mi.MemTotal,
-		NetworkBackend: r.config.Network.NetworkBackend,
-		OS:             runtime.GOOS,
-		SwapFree:       mi.SwapFree,
-		SwapTotal:      mi.SwapTotal,
+		Arch:            runtime.GOARCH,
+		BuildahVersion:  buildah.Version,
+		DatabaseBackend: r.config.Engine.DBBackend,
+		Linkmode:        linkmode.Linkmode(),
+		CPUs:            runtime.NumCPU(),
+		CPUUtilization:  cpuUtil,
+		Distribution:    hostDistributionInfo,
+		LogDriver:       r.config.Containers.LogDriver,
+		EventLogger:     r.eventer.String(),
+		Hostname:        host,
+		Kernel:          kv,
+		MemFree:         mi.MemFree,
+		MemTotal:        mi.MemTotal,
+		NetworkBackend:  r.config.Network.NetworkBackend,
+		OS:              runtime.GOOS,
+		SwapFree:        mi.SwapFree,
+		SwapTotal:       mi.SwapTotal,
 	}
 	if err := r.setPlatformHostInfo(&info); err != nil {
 		return nil, err

libpod/options.go

@@ -282,6 +282,16 @@ func WithRegistriesConf(path string) RuntimeOption {
 	}
 }
 
+// WithDatabaseBackend configures the runtime's database backend.
+func WithDatabaseBackend(value string) RuntimeOption {
+	logrus.Debugf("Setting custom database backend: %q", value)
+	return func(rt *Runtime) error {
+		// The value will be parsed later on.
+		rt.config.Engine.DBBackend = value
+		return nil
+	}
+}
+
 // WithHooksDir sets the directories to look for OCI runtime hook configuration.
 func WithHooksDir(hooksDirs ...string) RuntimeOption {
 	return func(rt *Runtime) error {

pkg/domain/entities/engine.go

@@ -34,6 +34,7 @@ type PodmanConfig struct {
 
 	ContainersConf           *config.Config
 	ContainersConfDefaultsRO *config.Config // The read-only! defaults from containers.conf.
+	DBBackend                string         // Hidden: change the database backend
 	DockerConfig             string         // Used for Docker compatibility
 	CgroupUsage              string         // rootless code determines Usage message
 	ConmonPath               string         // --conmon flag will set Engine.ConmonPath

pkg/domain/infra/runtime_libpod.go

@@ -265,6 +265,10 @@ func getRuntime(ctx context.Context, fs *flag.FlagSet, opts *engineOpts) (*libpo
 		options = append(options, libpod.WithRegistriesConf(cfg.RegistriesConf))
 	}
 
+	if fs.Changed("db-backend") {
+		options = append(options, libpod.WithDatabaseBackend(cfg.ContainersConf.Engine.DBBackend))
+	}
+
 	// no need to handle the error, it will return false anyway
 	if syslog, _ := fs.GetBool("syslog"); syslog {
 		options = append(options, libpod.WithSyslog())

test/system/005-info.bats

@@ -150,4 +150,16 @@ host.slirp4netns.executable | $expr_path
     fi
 }
 
+@test "podman --db-backend info - basic output" {
+    # TODO: this tests needs to change once sqlite is being tested in the system tests
+    skip_if_remote "--db-backend does not work on a remote client"
+    for backend in boltdb sqlite; do
+        run_podman --db-backend=$backend info --format "{{ .Host.DatabaseBackend }}"
+        is "$output" "$backend"
+    done
+
+    run_podman 125 --db-backend=bogus info --format "{{ .Host.DatabaseBackend }}"
+    is "$output" "Error: unsupported database backend: \"bogus\""
+}
+
 # vim: filetype=sh