268 lines
6.8 KiB
Go
268 lines
6.8 KiB
Go
// +build linux
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package main
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import (
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"encoding/json"
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"fmt"
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"io/ioutil"
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"os"
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"runtime"
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"github.com/opencontainers/runc/libcontainer/configs"
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"github.com/opencontainers/runtime-spec/specs-go"
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"github.com/urfave/cli"
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)
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var specCommand = cli.Command{
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Name: "spec",
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Usage: "create a new specification file",
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ArgsUsage: "",
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Description: `The spec command creates the new specification file named "` + specConfig + `" for
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the bundle.
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The spec generated is just a starter file. Editing of the spec is required to
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achieve desired results. For example, the newly generated spec includes an args
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parameter that is initially set to call the "sh" command when the container is
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started. Calling "sh" may work for an ubuntu container or busybox, but will not
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work for containers that do not include the "sh" program.
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EXAMPLE:
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To run docker's hello-world container one needs to set the args parameter
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in the spec to call hello. This can be done using the sed command or a text
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editor. The following commands create a bundle for hello-world, change the
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default args parameter in the spec from "sh" to "/hello", then run the hello
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command in a new hello-world container named container1:
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mkdir hello
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cd hello
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docker pull hello-world
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docker export $(docker create hello-world) > hello-world.tar
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mkdir rootfs
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tar -C rootfs -xf hello-world.tar
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runc spec
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sed -i 's;"sh";"/hello";' ` + specConfig + `
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runc run container1
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In the run command above, "container1" is the name for the instance of the
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container that you are starting. The name you provide for the container instance
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must be unique on your host.
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An alternative for generating a customized spec config is to use "oci-runtime-tool", the
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sub-command "oci-runtime-tool generate" has lots of options that can be used to do any
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customizations as you want, see [runtime-tools](https://github.com/opencontainers/runtime-tools)
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to get more information.
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When starting a container through runc, runc needs root privilege. If not
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already running as root, you can use sudo to give runc root privilege. For
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example: "sudo runc start container1" will give runc root privilege to start the
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container on your host.`,
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Flags: []cli.Flag{
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cli.StringFlag{
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Name: "bundle, b",
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Value: "",
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Usage: "path to the root of the bundle directory",
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},
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},
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Action: func(context *cli.Context) error {
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if err := checkArgs(context, 0, exactArgs); err != nil {
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return err
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}
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spec := specs.Spec{
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Version: specs.Version,
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Platform: specs.Platform{
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OS: runtime.GOOS,
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Arch: runtime.GOARCH,
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},
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Root: specs.Root{
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Path: "rootfs",
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Readonly: true,
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},
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Process: specs.Process{
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Terminal: true,
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User: specs.User{},
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Args: []string{
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"sh",
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},
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Env: []string{
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"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
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"TERM=xterm",
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},
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Cwd: "/",
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NoNewPrivileges: true,
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Capabilities: []string{
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"CAP_AUDIT_WRITE",
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"CAP_KILL",
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"CAP_NET_BIND_SERVICE",
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},
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Rlimits: []specs.LinuxRlimit{
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{
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Type: "RLIMIT_NOFILE",
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Hard: uint64(1024),
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Soft: uint64(1024),
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},
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},
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},
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Hostname: "runc",
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Mounts: []specs.Mount{
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{
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Destination: "/proc",
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Type: "proc",
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Source: "proc",
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Options: nil,
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},
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{
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Destination: "/dev",
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Type: "tmpfs",
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Source: "tmpfs",
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Options: []string{"nosuid", "strictatime", "mode=755", "size=65536k"},
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},
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{
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Destination: "/dev/pts",
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Type: "devpts",
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Source: "devpts",
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Options: []string{"nosuid", "noexec", "newinstance", "ptmxmode=0666", "mode=0620", "gid=5"},
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},
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{
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Destination: "/dev/shm",
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Type: "tmpfs",
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Source: "shm",
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Options: []string{"nosuid", "noexec", "nodev", "mode=1777", "size=65536k"},
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},
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{
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Destination: "/dev/mqueue",
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Type: "mqueue",
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Source: "mqueue",
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Options: []string{"nosuid", "noexec", "nodev"},
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},
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{
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Destination: "/sys",
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Type: "sysfs",
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Source: "sysfs",
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Options: []string{"nosuid", "noexec", "nodev", "ro"},
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},
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{
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Destination: "/sys/fs/cgroup",
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Type: "cgroup",
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Source: "cgroup",
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Options: []string{"nosuid", "noexec", "nodev", "relatime", "ro"},
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},
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},
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Linux: &specs.Linux{
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MaskedPaths: []string{
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"/proc/kcore",
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"/proc/latency_stats",
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"/proc/timer_list",
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"/proc/timer_stats",
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"/proc/sched_debug",
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"/sys/firmware",
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},
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ReadonlyPaths: []string{
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"/proc/asound",
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"/proc/bus",
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"/proc/fs",
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"/proc/irq",
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"/proc/sys",
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"/proc/sysrq-trigger",
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},
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Resources: &specs.LinuxResources{
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Devices: []specs.LinuxDeviceCgroup{
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{
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Allow: false,
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Access: sPtr("rwm"),
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},
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},
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},
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Namespaces: []specs.LinuxNamespace{
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{
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Type: "pid",
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},
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{
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Type: "network",
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},
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{
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Type: "ipc",
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},
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{
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Type: "uts",
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},
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{
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Type: "mount",
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},
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},
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},
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}
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checkNoFile := func(name string) error {
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_, err := os.Stat(name)
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if err == nil {
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return fmt.Errorf("File %s exists. Remove it first", name)
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}
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if !os.IsNotExist(err) {
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return err
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}
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return nil
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}
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bundle := context.String("bundle")
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if bundle != "" {
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if err := os.Chdir(bundle); err != nil {
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return err
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}
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}
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if err := checkNoFile(specConfig); err != nil {
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return err
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}
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data, err := json.MarshalIndent(&spec, "", "\t")
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if err != nil {
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return err
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}
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if err := ioutil.WriteFile(specConfig, data, 0666); err != nil {
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return err
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}
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return nil
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},
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}
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func sPtr(s string) *string { return &s }
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// loadSpec loads the specification from the provided path.
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func loadSpec(cPath string) (spec *specs.Spec, err error) {
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cf, err := os.Open(cPath)
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if err != nil {
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if os.IsNotExist(err) {
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return nil, fmt.Errorf("JSON specification file %s not found", cPath)
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}
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return nil, err
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}
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defer cf.Close()
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if err = json.NewDecoder(cf).Decode(&spec); err != nil {
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return nil, err
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}
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if err = validatePlatform(&spec.Platform); err != nil {
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return nil, err
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}
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return spec, validateProcessSpec(&spec.Process)
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}
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func createLibContainerRlimit(rlimit specs.LinuxRlimit) (configs.Rlimit, error) {
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rl, err := strToRlimit(rlimit.Type)
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if err != nil {
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return configs.Rlimit{}, err
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}
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return configs.Rlimit{
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Type: rl,
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Hard: rlimit.Hard,
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Soft: rlimit.Soft,
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}, nil
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}
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func validatePlatform(platform *specs.Platform) error {
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if platform.OS != runtime.GOOS {
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return fmt.Errorf("target os %s mismatch with current os %s", platform.OS, runtime.GOOS)
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}
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if platform.Arch != runtime.GOARCH {
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return fmt.Errorf("target arch %s mismatch with current arch %s", platform.Arch, runtime.GOARCH)
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}
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return nil
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}
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