diff options
Diffstat (limited to 'runsc/config')
| -rw-r--r-- | runsc/config/BUILD | 28 | ||||
| -rw-r--r-- | runsc/config/config.go | 339 | ||||
| -rw-r--r-- | runsc/config/config_test.go | 272 | ||||
| -rw-r--r-- | runsc/config/flags.go | 205 |
4 files changed, 844 insertions, 0 deletions
diff --git a/runsc/config/BUILD b/runsc/config/BUILD new file mode 100644 index 000000000..b1672bb9d --- /dev/null +++ b/runsc/config/BUILD @@ -0,0 +1,28 @@ +load("//tools:defs.bzl", "go_library", "go_test") + +package(licenses = ["notice"]) + +go_library( + name = "config", + srcs = [ + "config.go", + "flags.go", + ], + visibility = ["//:sandbox"], + deps = [ + "//pkg/refs", + "//pkg/sentry/watchdog", + "//pkg/sync", + "//runsc/flag", + ], +) + +go_test( + name = "config_test", + size = "small", + srcs = [ + "config_test.go", + ], + library = ":config", + deps = ["//runsc/flag"], +) diff --git a/runsc/config/config.go b/runsc/config/config.go new file mode 100644 index 000000000..f30f79f68 --- /dev/null +++ b/runsc/config/config.go @@ -0,0 +1,339 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +// Package config provides basic infrastructure to set configuration settings +// for runsc. The configuration is set by flags to the command line. They can +// also propagate to a different process using the same flags. +package config + +import ( + "fmt" + + "gvisor.dev/gvisor/pkg/refs" + "gvisor.dev/gvisor/pkg/sentry/watchdog" +) + +// Config holds configuration that is not part of the runtime spec. +// +// Follow these steps to add a new flag: +// 1. Create a new field in Config. +// 2. Add a field tag with the flag name +// 3. Register a new flag in flags.go, with name and description +// 4. Add any necessary validation into validate() +// 5. If adding an enum, follow the same pattern as FileAccessType +// +type Config struct { + // RootDir is the runtime root directory. + RootDir string `flag:"root"` + + // Debug indicates that debug logging should be enabled. + Debug bool `flag:"debug"` + + // LogFilename is the filename to log to, if not empty. + LogFilename string `flag:"log"` + + // LogFormat is the log format. + LogFormat string `flag:"log-format"` + + // DebugLog is the path to log debug information to, if not empty. + DebugLog string `flag:"debug-log"` + + // PanicLog is the path to log GO's runtime messages, if not empty. + PanicLog string `flag:"panic-log"` + + // DebugLogFormat is the log format for debug. + DebugLogFormat string `flag:"debug-log-format"` + + // FileAccess indicates how the filesystem is accessed. + FileAccess FileAccessType `flag:"file-access"` + + // Overlay is whether to wrap the root filesystem in an overlay. + Overlay bool `flag:"overlay"` + + // FSGoferHostUDS enables the gofer to mount a host UDS. + FSGoferHostUDS bool `flag:"fsgofer-host-uds"` + + // Network indicates what type of network to use. + Network NetworkType `flag:"network"` + + // EnableRaw indicates whether raw sockets should be enabled. Raw + // sockets are disabled by stripping CAP_NET_RAW from the list of + // capabilities. + EnableRaw bool `flag:"net-raw"` + + // HardwareGSO indicates that hardware segmentation offload is enabled. + HardwareGSO bool `flag:"gso"` + + // SoftwareGSO indicates that software segmentation offload is enabled. + SoftwareGSO bool `flag:"software-gso"` + + // TXChecksumOffload indicates that TX Checksum Offload is enabled. + TXChecksumOffload bool `flag:"tx-checksum-offload"` + + // RXChecksumOffload indicates that RX Checksum Offload is enabled. + RXChecksumOffload bool `flag:"rx-checksum-offload"` + + // QDisc indicates the type of queuening discipline to use by default + // for non-loopback interfaces. + QDisc QueueingDiscipline `flag:"qdisc"` + + // LogPackets indicates that all network packets should be logged. + LogPackets bool `flag:"log-packets"` + + // Platform is the platform to run on. + Platform string `flag:"platform"` + + // Strace indicates that strace should be enabled. + Strace bool `flag:"strace"` + + // StraceSyscalls is the set of syscalls to trace (comma-separated values). + // If StraceEnable is true and this string is empty, then all syscalls will + // be traced. + StraceSyscalls string `flag:"strace-syscalls"` + + // StraceLogSize is the max size of data blobs to display. + StraceLogSize uint `flag:"strace-log-size"` + + // DisableSeccomp indicates whether seccomp syscall filters should be + // disabled. Pardon the double negation, but default to enabled is important. + DisableSeccomp bool + + // WatchdogAction sets what action the watchdog takes when triggered. + WatchdogAction watchdog.Action `flag:"watchdog-action"` + + // PanicSignal registers signal handling that panics. Usually set to + // SIGUSR2(12) to troubleshoot hangs. -1 disables it. + PanicSignal int `flag:"panic-signal"` + + // ProfileEnable is set to prepare the sandbox to be profiled. + ProfileEnable bool `flag:"profile"` + + // RestoreFile is the path to the saved container image + RestoreFile string + + // NumNetworkChannels controls the number of AF_PACKET sockets that map + // to the same underlying network device. This allows netstack to better + // scale for high throughput use cases. + NumNetworkChannels int `flag:"num-network-channels"` + + // Rootless allows the sandbox to be started with a user that is not root. + // Defense is depth measures are weaker with rootless. Specifically, the + // sandbox and Gofer process run as root inside a user namespace with root + // mapped to the caller's user. + Rootless bool `flag:"rootless"` + + // AlsoLogToStderr allows to send log messages to stderr. + AlsoLogToStderr bool `flag:"alsologtostderr"` + + // ReferenceLeakMode sets reference leak check mode + ReferenceLeak refs.LeakMode `flag:"ref-leak-mode"` + + // OverlayfsStaleRead instructs the sandbox to assume that the root mount + // is on a Linux overlayfs mount, which does not necessarily preserve + // coherence between read-only and subsequent writable file descriptors + // representing the "same" file. + OverlayfsStaleRead bool `flag:"overlayfs-stale-read"` + + // CPUNumFromQuota sets CPU number count to available CPU quota, using + // least integer value greater than or equal to quota. + // + // E.g. 0.2 CPU quota will result in 1, and 1.9 in 2. + CPUNumFromQuota bool `flag:"cpu-num-from-quota"` + + // Enables VFS2. + VFS2 bool `flag:"vfs2"` + + // Enables FUSE usage. + FUSE bool `flag:"fuse"` + + // Allows overriding of flags in OCI annotations. + AllowFlagOverride bool `flag:"allow-flag-override"` + + // Enables seccomp inside the sandbox. + OCISeccomp bool `flag:"oci-seccomp"` + + // TestOnlyAllowRunAsCurrentUserWithoutChroot should only be used in + // tests. It allows runsc to start the sandbox process as the current + // user, and without chrooting the sandbox process. This can be + // necessary in test environments that have limited capabilities. + TestOnlyAllowRunAsCurrentUserWithoutChroot bool `flag:"TESTONLY-unsafe-nonroot"` + + // TestOnlyTestNameEnv should only be used in tests. It looks up for the + // test name in the container environment variables and adds it to the debug + // log file name. This is done to help identify the log with the test when + // multiple tests are run in parallel, since there is no way to pass + // parameters to the runtime from docker. + TestOnlyTestNameEnv string `flag:"TESTONLY-test-name-env"` +} + +func (c *Config) validate() error { + if c.FileAccess == FileAccessShared && c.Overlay { + return fmt.Errorf("overlay flag is incompatible with shared file access") + } + if c.NumNetworkChannels <= 0 { + return fmt.Errorf("num_network_channels must be > 0, got: %d", c.NumNetworkChannels) + } + return nil +} + +// FileAccessType tells how the filesystem is accessed. +type FileAccessType int + +const ( + // FileAccessExclusive is the same as FileAccessShared, but enables + // extra caching for improved performance. It should only be used if + // the sandbox has exclusive access to the filesystem. + FileAccessExclusive FileAccessType = iota + + // FileAccessShared sends IO requests to a Gofer process that validates the + // requests and forwards them to the host. + FileAccessShared +) + +func fileAccessTypePtr(v FileAccessType) *FileAccessType { + return &v +} + +// Set implements flag.Value. +func (f *FileAccessType) Set(v string) error { + switch v { + case "shared": + *f = FileAccessShared + case "exclusive": + *f = FileAccessExclusive + default: + return fmt.Errorf("invalid file access type %q", v) + } + return nil +} + +// Get implements flag.Value. +func (f *FileAccessType) Get() interface{} { + return *f +} + +// String implements flag.Value. +func (f *FileAccessType) String() string { + switch *f { + case FileAccessShared: + return "shared" + case FileAccessExclusive: + return "exclusive" + } + panic(fmt.Sprintf("Invalid file access type %v", *f)) +} + +// NetworkType tells which network stack to use. +type NetworkType int + +const ( + // NetworkSandbox uses internal network stack, isolated from the host. + NetworkSandbox NetworkType = iota + + // NetworkHost redirects network related syscalls to the host network. + NetworkHost + + // NetworkNone sets up just loopback using netstack. + NetworkNone +) + +func networkTypePtr(v NetworkType) *NetworkType { + return &v +} + +// Set implements flag.Value. +func (n *NetworkType) Set(v string) error { + switch v { + case "sandbox": + *n = NetworkSandbox + case "host": + *n = NetworkHost + case "none": + *n = NetworkNone + default: + return fmt.Errorf("invalid network type %q", v) + } + return nil +} + +// Get implements flag.Value. +func (n *NetworkType) Get() interface{} { + return *n +} + +// String implements flag.Value. +func (n *NetworkType) String() string { + switch *n { + case NetworkSandbox: + return "sandbox" + case NetworkHost: + return "host" + case NetworkNone: + return "none" + } + panic(fmt.Sprintf("Invalid network type %v", *n)) +} + +// QueueingDiscipline is used to specify the kind of Queueing Discipline to +// apply for a give FDBasedLink. +type QueueingDiscipline int + +const ( + // QDiscNone disables any queueing for the underlying FD. + QDiscNone QueueingDiscipline = iota + + // QDiscFIFO applies a simple fifo based queue to the underlying FD. + QDiscFIFO +) + +func queueingDisciplinePtr(v QueueingDiscipline) *QueueingDiscipline { + return &v +} + +// Set implements flag.Value. +func (q *QueueingDiscipline) Set(v string) error { + switch v { + case "none": + *q = QDiscNone + case "fifo": + *q = QDiscFIFO + default: + return fmt.Errorf("invalid qdisc %q", v) + } + return nil +} + +// Get implements flag.Value. +func (q *QueueingDiscipline) Get() interface{} { + return *q +} + +// String implements flag.Value. +func (q *QueueingDiscipline) String() string { + switch *q { + case QDiscNone: + return "none" + case QDiscFIFO: + return "fifo" + } + panic(fmt.Sprintf("Invalid qdisc %v", *q)) +} + +func leakModePtr(v refs.LeakMode) *refs.LeakMode { + return &v +} + +func watchdogActionPtr(v watchdog.Action) *watchdog.Action { + return &v +} diff --git a/runsc/config/config_test.go b/runsc/config/config_test.go new file mode 100644 index 000000000..fb162b7eb --- /dev/null +++ b/runsc/config/config_test.go @@ -0,0 +1,272 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package config + +import ( + "strings" + "testing" + + "gvisor.dev/gvisor/runsc/flag" +) + +func init() { + RegisterFlags() +} + +func TestDefault(t *testing.T) { + c, err := NewFromFlags() + if err != nil { + t.Fatal(err) + } + // "--root" is always set to something different than the default. Reset it + // to make it easier to test that default values do not generate flags. + c.RootDir = "" + + // All defaults doesn't require setting flags. + flags := c.ToFlags() + if len(flags) > 0 { + t.Errorf("default flags not set correctly for: %s", flags) + } +} + +func setDefault(name string) { + fl := flag.CommandLine.Lookup(name) + fl.Value.Set(fl.DefValue) +} + +func TestFromFlags(t *testing.T) { + flag.CommandLine.Lookup("root").Value.Set("some-path") + flag.CommandLine.Lookup("debug").Value.Set("true") + flag.CommandLine.Lookup("num-network-channels").Value.Set("123") + flag.CommandLine.Lookup("network").Value.Set("none") + defer func() { + setDefault("root") + setDefault("debug") + setDefault("num-network-channels") + setDefault("network") + }() + + c, err := NewFromFlags() + if err != nil { + t.Fatal(err) + } + if want := "some-path"; c.RootDir != want { + t.Errorf("RootDir=%v, want: %v", c.RootDir, want) + } + if want := true; c.Debug != want { + t.Errorf("Debug=%v, want: %v", c.Debug, want) + } + if want := 123; c.NumNetworkChannels != want { + t.Errorf("NumNetworkChannels=%v, want: %v", c.NumNetworkChannels, want) + } + if want := NetworkNone; c.Network != want { + t.Errorf("Network=%v, want: %v", c.Network, want) + } +} + +func TestToFlags(t *testing.T) { + c, err := NewFromFlags() + if err != nil { + t.Fatal(err) + } + c.RootDir = "some-path" + c.Debug = true + c.NumNetworkChannels = 123 + c.Network = NetworkNone + + flags := c.ToFlags() + if len(flags) != 4 { + t.Errorf("wrong number of flags set, want: 4, got: %d: %s", len(flags), flags) + } + t.Logf("Flags: %s", flags) + fm := map[string]string{} + for _, f := range flags { + kv := strings.Split(f, "=") + fm[kv[0]] = kv[1] + } + for name, want := range map[string]string{ + "--root": "some-path", + "--debug": "true", + "--num-network-channels": "123", + "--network": "none", + } { + if got, ok := fm[name]; ok { + if got != want { + t.Errorf("flag %q, want: %q, got: %q", name, want, got) + } + } else { + t.Errorf("flag %q not set", name) + } + } +} + +// TestInvalidFlags checks that enum flags fail when value is not in enum set. +func TestInvalidFlags(t *testing.T) { + for _, tc := range []struct { + name string + error string + }{ + { + name: "file-access", + error: "invalid file access type", + }, + { + name: "network", + error: "invalid network type", + }, + { + name: "qdisc", + error: "invalid qdisc", + }, + { + name: "watchdog-action", + error: "invalid watchdog action", + }, + { + name: "ref-leak-mode", + error: "invalid ref leak mode", + }, + } { + t.Run(tc.name, func(t *testing.T) { + defer setDefault(tc.name) + if err := flag.CommandLine.Lookup(tc.name).Value.Set("invalid"); err == nil || !strings.Contains(err.Error(), tc.error) { + t.Errorf("flag.Value.Set(invalid) wrong error reported: %v", err) + } + }) + } +} + +func TestValidationFail(t *testing.T) { + for _, tc := range []struct { + name string + flags map[string]string + error string + }{ + { + name: "shared+overlay", + flags: map[string]string{ + "file-access": "shared", + "overlay": "true", + }, + error: "overlay flag is incompatible", + }, + { + name: "network-channels", + flags: map[string]string{ + "num-network-channels": "-1", + }, + error: "num_network_channels must be > 0", + }, + } { + t.Run(tc.name, func(t *testing.T) { + for name, val := range tc.flags { + defer setDefault(name) + if err := flag.CommandLine.Lookup(name).Value.Set(val); err != nil { + t.Errorf("%s=%q: %v", name, val, err) + } + } + if _, err := NewFromFlags(); err == nil || !strings.Contains(err.Error(), tc.error) { + t.Errorf("NewFromFlags() wrong error reported: %v", err) + } + }) + } +} + +func TestOverride(t *testing.T) { + c, err := NewFromFlags() + if err != nil { + t.Fatal(err) + } + c.AllowFlagOverride = true + + t.Run("string", func(t *testing.T) { + c.RootDir = "foobar" + if err := c.Override("root", "bar"); err != nil { + t.Fatalf("Override(root, bar) failed: %v", err) + } + defer setDefault("root") + if c.RootDir != "bar" { + t.Errorf("Override(root, bar) didn't work: %+v", c) + } + }) + + t.Run("bool", func(t *testing.T) { + c.Debug = true + if err := c.Override("debug", "false"); err != nil { + t.Fatalf("Override(debug, false) failed: %v", err) + } + defer setDefault("debug") + if c.Debug { + t.Errorf("Override(debug, false) didn't work: %+v", c) + } + }) + + t.Run("enum", func(t *testing.T) { + c.FileAccess = FileAccessShared + if err := c.Override("file-access", "exclusive"); err != nil { + t.Fatalf("Override(file-access, exclusive) failed: %v", err) + } + defer setDefault("file-access") + if c.FileAccess != FileAccessExclusive { + t.Errorf("Override(file-access, exclusive) didn't work: %+v", c) + } + }) +} + +func TestOverrideDisabled(t *testing.T) { + c, err := NewFromFlags() + if err != nil { + t.Fatal(err) + } + const errMsg = "flag override disabled" + if err := c.Override("root", "path"); err == nil || !strings.Contains(err.Error(), errMsg) { + t.Errorf("Override() wrong error: %v", err) + } +} + +func TestOverrideError(t *testing.T) { + c, err := NewFromFlags() + if err != nil { + t.Fatal(err) + } + c.AllowFlagOverride = true + for _, tc := range []struct { + name string + value string + error string + }{ + { + name: "invalid", + value: "valid", + error: `flag "invalid" not found`, + }, + { + name: "debug", + value: "invalid", + error: "error setting flag debug", + }, + { + name: "file-access", + value: "invalid", + error: "invalid file access type", + }, + } { + t.Run(tc.name, func(t *testing.T) { + if err := c.Override(tc.name, tc.value); err == nil || !strings.Contains(err.Error(), tc.error) { + t.Errorf("Override(%q, %q) wrong error: %v", tc.name, tc.value, err) + } + }) + } +} diff --git a/runsc/config/flags.go b/runsc/config/flags.go new file mode 100644 index 000000000..a5f25cfa2 --- /dev/null +++ b/runsc/config/flags.go @@ -0,0 +1,205 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package config + +import ( + "fmt" + "os" + "path/filepath" + "reflect" + "strconv" + + "gvisor.dev/gvisor/pkg/refs" + "gvisor.dev/gvisor/pkg/sentry/watchdog" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/runsc/flag" +) + +var registration sync.Once + +// This is the set of flags used to populate Config. +func RegisterFlags() { + registration.Do(func() { + // Although these flags are not part of the OCI spec, they are used by + // Docker, and thus should not be changed. + flag.String("root", "", "root directory for storage of container state.") + flag.String("log", "", "file path where internal debug information is written, default is stdout.") + flag.String("log-format", "text", "log format: text (default), json, or json-k8s.") + flag.Bool("debug", false, "enable debug logging.") + + // These flags are unique to runsc, and are used to configure parts of the + // system that are not covered by the runtime spec. + + // Debugging flags. + flag.String("debug-log", "", "additional location for logs. If it ends with '/', log files are created inside the directory with default names. The following variables are available: %TIMESTAMP%, %COMMAND%.") + flag.String("panic-log", "", "file path were panic reports and other Go's runtime messages are written.") + flag.Bool("log-packets", false, "enable network packet logging.") + flag.String("debug-log-format", "text", "log format: text (default), json, or json-k8s.") + flag.Bool("alsologtostderr", false, "send log messages to stderr.") + flag.Bool("allow-flag-override", false, "allow OCI annotations (dev.gvisor.flag.<name>) to override flags for debugging.") + + // Debugging flags: strace related + flag.Bool("strace", false, "enable strace.") + flag.String("strace-syscalls", "", "comma-separated list of syscalls to trace. If --strace is true and this list is empty, then all syscalls will be traced.") + flag.Uint("strace-log-size", 1024, "default size (in bytes) to log data argument blobs.") + + // Flags that control sandbox runtime behavior. + flag.String("platform", "ptrace", "specifies which platform to use: ptrace (default), kvm.") + flag.Var(watchdogActionPtr(watchdog.LogWarning), "watchdog-action", "sets what action the watchdog takes when triggered: log (default), panic.") + flag.Int("panic-signal", -1, "register signal handling that panics. Usually set to SIGUSR2(12) to troubleshoot hangs. -1 disables it.") + flag.Bool("profile", false, "prepares the sandbox to use Golang profiler. Note that enabling profiler loosens the seccomp protection added to the sandbox (DO NOT USE IN PRODUCTION).") + flag.Bool("rootless", false, "it allows the sandbox to be started with a user that is not root. Sandbox and Gofer processes may run with same privileges as current user.") + flag.Var(leakModePtr(refs.NoLeakChecking), "ref-leak-mode", "sets reference leak check mode: disabled (default), log-names, log-traces.") + flag.Bool("cpu-num-from-quota", false, "set cpu number to cpu quota (least integer greater or equal to quota value, but not less than 2)") + flag.Bool("oci-seccomp", false, "Enables loading OCI seccomp filters inside the sandbox.") + + // Flags that control sandbox runtime behavior: FS related. + flag.Var(fileAccessTypePtr(FileAccessExclusive), "file-access", "specifies which filesystem to use for the root mount: exclusive (default), shared. Volume mounts are always shared.") + flag.Bool("overlay", false, "wrap filesystem mounts with writable overlay. All modifications are stored in memory inside the sandbox.") + flag.Bool("overlayfs-stale-read", true, "assume root mount is an overlay filesystem") + flag.Bool("fsgofer-host-uds", false, "allow the gofer to mount Unix Domain Sockets.") + flag.Bool("vfs2", false, "TEST ONLY; use while VFSv2 is landing. This uses the new experimental VFS layer.") + flag.Bool("fuse", false, "TEST ONLY; use while FUSE in VFSv2 is landing. This allows the use of the new experimental FUSE filesystem.") + + // Flags that control sandbox runtime behavior: network related. + flag.Var(networkTypePtr(NetworkSandbox), "network", "specifies which network to use: sandbox (default), host, none. Using network inside the sandbox is more secure because it's isolated from the host network.") + flag.Bool("net-raw", false, "enable raw sockets. When false, raw sockets are disabled by removing CAP_NET_RAW from containers (`runsc exec` will still be able to utilize raw sockets). Raw sockets allow malicious containers to craft packets and potentially attack the network.") + flag.Bool("gso", true, "enable hardware segmentation offload if it is supported by a network device.") + flag.Bool("software-gso", true, "enable software segmentation offload when hardware offload can't be enabled.") + flag.Bool("tx-checksum-offload", false, "enable TX checksum offload.") + flag.Bool("rx-checksum-offload", true, "enable RX checksum offload.") + flag.Var(queueingDisciplinePtr(QDiscFIFO), "qdisc", "specifies which queueing discipline to apply by default to the non loopback nics used by the sandbox.") + flag.Int("num-network-channels", 1, "number of underlying channels(FDs) to use for network link endpoints.") + + // Test flags, not to be used outside tests, ever. + flag.Bool("TESTONLY-unsafe-nonroot", false, "TEST ONLY; do not ever use! This skips many security measures that isolate the host from the sandbox.") + flag.String("TESTONLY-test-name-env", "", "TEST ONLY; do not ever use! Used for automated tests to improve logging.") + }) +} + +// NewFromFlags creates a new Config with values coming from command line flags. +func NewFromFlags() (*Config, error) { + conf := &Config{} + + obj := reflect.ValueOf(conf).Elem() + st := obj.Type() + for i := 0; i < st.NumField(); i++ { + f := st.Field(i) + name, ok := f.Tag.Lookup("flag") + if !ok { + // No flag set for this field. + continue + } + fl := flag.CommandLine.Lookup(name) + if fl == nil { + panic(fmt.Sprintf("Flag %q not found", name)) + } + x := reflect.ValueOf(flag.Get(fl.Value)) + obj.Field(i).Set(x) + } + + if len(conf.RootDir) == 0 { + // If not set, set default root dir to something (hopefully) user-writeable. + conf.RootDir = "/var/run/runsc" + if runtimeDir := os.Getenv("XDG_RUNTIME_DIR"); runtimeDir != "" { + conf.RootDir = filepath.Join(runtimeDir, "runsc") + } + } + + if err := conf.validate(); err != nil { + return nil, err + } + return conf, nil +} + +// ToFlags returns a slice of flags that correspond to the given Config. +func (c *Config) ToFlags() []string { + var rv []string + + obj := reflect.ValueOf(c).Elem() + st := obj.Type() + for i := 0; i < st.NumField(); i++ { + f := st.Field(i) + name, ok := f.Tag.Lookup("flag") + if !ok { + // No flag set for this field. + continue + } + val := getVal(obj.Field(i)) + + flag := flag.CommandLine.Lookup(name) + if flag == nil { + panic(fmt.Sprintf("Flag %q not found", name)) + } + if val == flag.DefValue { + continue + } + rv = append(rv, fmt.Sprintf("--%s=%s", flag.Name, val)) + } + return rv +} + +// Override writes a new value to a flag. +func (c *Config) Override(name string, value string) error { + if !c.AllowFlagOverride { + return fmt.Errorf("flag override disabled, use --allow-flag-override to enable it") + } + + obj := reflect.ValueOf(c).Elem() + st := obj.Type() + for i := 0; i < st.NumField(); i++ { + f := st.Field(i) + fieldName, ok := f.Tag.Lookup("flag") + if !ok || fieldName != name { + // Not a flag field, or flag name doesn't match. + continue + } + fl := flag.CommandLine.Lookup(name) + if fl == nil { + // Flag must exist if there is a field match above. + panic(fmt.Sprintf("Flag %q not found", name)) + } + + // Use flag to convert the string value to the underlying flag type, using + // the same rules as the command-line for consistency. + if err := fl.Value.Set(value); err != nil { + return fmt.Errorf("error setting flag %s=%q: %w", name, value, err) + } + x := reflect.ValueOf(flag.Get(fl.Value)) + obj.Field(i).Set(x) + + // Validates the config again to ensure it's left in a consistent state. + return c.validate() + } + return fmt.Errorf("flag %q not found. Cannot set it to %q", name, value) +} + +func getVal(field reflect.Value) string { + if str, ok := field.Addr().Interface().(fmt.Stringer); ok { + return str.String() + } + switch field.Kind() { + case reflect.Bool: + return strconv.FormatBool(field.Bool()) + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + return strconv.FormatInt(field.Int(), 10) + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + return strconv.FormatUint(field.Uint(), 10) + case reflect.String: + return field.String() + default: + panic("unknown type " + field.Kind().String()) + } +} |