runtime-spec/features.md

Features Structure

A runtime MAY provide a JSON structure about its implemented features to runtime callers. This JSON structure is called "Features structure".

The Features structure is irrelevant to the actual availability of the features in the host operating system. Hence, the content of the Features structure SHOULD be determined on the compilation time of the runtime, not on the execution time.

All properties in the Features structure except ociVersionMin and ociVersionMax MAY either be absent or have the null value. The null value MUST NOT be confused with an empty value such as 0, false, "", [], and {}.

Specification version

• ociVersionMin (string, REQUIRED) The minimum recognized version of the Open Container Initiative Runtime Specification. The runtime MUST accept this value as the ociVersion property of config.json.

• ociVersionMax (string, REQUIRED) The maximum recognized version of the Open Container Initiative Runtime Specification. The runtime MUST accept this value as the ociVersion property of config.json. The value MUST NOT be less than the value of the ociVersionMin property. The Features structure MUST NOT contain properties that are not defined in this version of the Open Container Initiative Runtime Specification.

Example

{
  "ociVersionMin": "1.0.0",
  "ociVersionMax": "1.1.0"
}

Hooks

• hooks (array of strings, OPTIONAL) The recognized names of the hooks. The runtime MUST support the elements in this array as the hooks property of config.json.

Example

"hooks": [
  "prestart",
  "createRuntime",
  "createContainer",
  "startContainer",
  "poststart",
  "poststop"
]

Mount Options

• mountOptions (array of strings, OPTIONAL) The recognized names of the mount options, including options that might not be supported by the host operating system. The runtime MUST recognize the elements in this array as the options of mounts objects in config.json.
  • Linux: this array SHOULD NOT contain filesystem-specific mount options that are passed to the mount(2) syscall as const void *data.

Example

"mountOptions": [
  "acl",
  "async",
  "atime",
  "bind",
  "defaults",
  "dev",
  "diratime",
  "dirsync",
  "exec",
  "iversion",
  "lazytime",
  "loud",
  "mand",
  "noacl",
  "noatime",
  "nodev",
  "nodiratime",
  "noexec",
  "noiversion",
  "nolazytime",
  "nomand",
  "norelatime",
  "nostrictatime",
  "nosuid",
  "nosymfollow",
  "private",
  "ratime",
  "rbind",
  "rdev",
  "rdiratime",
  "relatime",
  "remount",
  "rexec",
  "rnoatime",
  "rnodev",
  "rnodiratime",
  "rnoexec",
  "rnorelatime",
  "rnostrictatime",
  "rnosuid",
  "rnosymfollow",
  "ro",
  "rprivate",
  "rrelatime",
  "rro",
  "rrw",
  "rshared",
  "rslave",
  "rstrictatime",
  "rsuid",
  "rsymfollow",
  "runbindable",
  "rw",
  "shared",
  "silent",
  "slave",
  "strictatime",
  "suid",
  "symfollow",
  "sync",
  "tmpcopyup",
  "unbindable"
]

Platform-specific features

• linux (object, OPTIONAL) Linux-specific features. This MAY be set if the runtime supports linux platform.

Annotations

annotations (object, OPTIONAL) contains arbitrary metadata of the runtime. This information MAY be structured or unstructured. Annotations MUST be a key-value map that follows the same convention as the Key and Values of the annotations property of config.json. However, annotations do not need to contain the possible values of the annotations property of config.json. The current version of the spec do not provide a way to enumerate the possible values of the annotations property of config.json.

Example

"annotations": {
  "org.opencontainers.runc.checkpoint.enabled": "true",
  "org.opencontainers.runc.version": "1.1.0"
}

Unsafe annotations in config.json

potentiallyUnsafeConfigAnnotations (array of strings, OPTIONAL) contains values of annotations property of config.json that may potentially change the behavior of the runtime.

A value that ends with "." is interpreted as a prefix of annotations.

Example

"potentiallyUnsafeConfigAnnotations": [
  "com.example.foo.bar",
  "org.systemd.property."
]

The example above matches com.example.foo.bar, org.systemd.property.ExecStartPre, etc. The example does not match com.example.foo.bar.baz.

Example

Here is a full example for reference.

{
  "ociVersionMin": "1.0.0",
  "ociVersionMax": "1.1.0-rc.2",
  "hooks": [
    "prestart",
    "createRuntime",
    "createContainer",
    "startContainer",
    "poststart",
    "poststop"
  ],
  "mountOptions": [
    "async",
    "atime",
    "bind",
    "defaults",
    "dev",
    "diratime",
    "dirsync",
    "exec",
    "iversion",
    "lazytime",
    "loud",
    "mand",
    "noatime",
    "nodev",
    "nodiratime",
    "noexec",
    "noiversion",
    "nolazytime",
    "nomand",
    "norelatime",
    "nostrictatime",
    "nosuid",
    "nosymfollow",
    "private",
    "ratime",
    "rbind",
    "rdev",
    "rdiratime",
    "relatime",
    "remount",
    "rexec",
    "rnoatime",
    "rnodev",
    "rnodiratime",
    "rnoexec",
    "rnorelatime",
    "rnostrictatime",
    "rnosuid",
    "rnosymfollow",
    "ro",
    "rprivate",
    "rrelatime",
    "rro",
    "rrw",
    "rshared",
    "rslave",
    "rstrictatime",
    "rsuid",
    "rsymfollow",
    "runbindable",
    "rw",
    "shared",
    "silent",
    "slave",
    "strictatime",
    "suid",
    "symfollow",
    "sync",
    "tmpcopyup",
    "unbindable"
  ],
  "linux": {
    "namespaces": [
      "cgroup",
      "ipc",
      "mount",
      "network",
      "pid",
      "user",
      "uts"
    ],
    "capabilities": [
      "CAP_CHOWN",
      "CAP_DAC_OVERRIDE",
      "CAP_DAC_READ_SEARCH",
      "CAP_FOWNER",
      "CAP_FSETID",
      "CAP_KILL",
      "CAP_SETGID",
      "CAP_SETUID",
      "CAP_SETPCAP",
      "CAP_LINUX_IMMUTABLE",
      "CAP_NET_BIND_SERVICE",
      "CAP_NET_BROADCAST",
      "CAP_NET_ADMIN",
      "CAP_NET_RAW",
      "CAP_IPC_LOCK",
      "CAP_IPC_OWNER",
      "CAP_SYS_MODULE",
      "CAP_SYS_RAWIO",
      "CAP_SYS_CHROOT",
      "CAP_SYS_PTRACE",
      "CAP_SYS_PACCT",
      "CAP_SYS_ADMIN",
      "CAP_SYS_BOOT",
      "CAP_SYS_NICE",
      "CAP_SYS_RESOURCE",
      "CAP_SYS_TIME",
      "CAP_SYS_TTY_CONFIG",
      "CAP_MKNOD",
      "CAP_LEASE",
      "CAP_AUDIT_WRITE",
      "CAP_AUDIT_CONTROL",
      "CAP_SETFCAP",
      "CAP_MAC_OVERRIDE",
      "CAP_MAC_ADMIN",
      "CAP_SYSLOG",
      "CAP_WAKE_ALARM",
      "CAP_BLOCK_SUSPEND",
      "CAP_AUDIT_READ",
      "CAP_PERFMON",
      "CAP_BPF",
      "CAP_CHECKPOINT_RESTORE"
    ],
    "cgroup": {
      "v1": true,
      "v2": true,
      "systemd": true,
      "systemdUser": true,
      "rdma": true
    },
    "seccomp": {
      "enabled": true,
      "actions": [
        "SCMP_ACT_ALLOW",
        "SCMP_ACT_ERRNO",
        "SCMP_ACT_KILL",
        "SCMP_ACT_KILL_PROCESS",
        "SCMP_ACT_KILL_THREAD",
        "SCMP_ACT_LOG",
        "SCMP_ACT_NOTIFY",
        "SCMP_ACT_TRACE",
        "SCMP_ACT_TRAP"
      ],
      "operators": [
        "SCMP_CMP_EQ",
        "SCMP_CMP_GE",
        "SCMP_CMP_GT",
        "SCMP_CMP_LE",
        "SCMP_CMP_LT",
        "SCMP_CMP_MASKED_EQ",
        "SCMP_CMP_NE"
      ],
      "archs": [
        "SCMP_ARCH_AARCH64",
        "SCMP_ARCH_ARM",
        "SCMP_ARCH_MIPS",
        "SCMP_ARCH_MIPS64",
        "SCMP_ARCH_MIPS64N32",
        "SCMP_ARCH_MIPSEL",
        "SCMP_ARCH_MIPSEL64",
        "SCMP_ARCH_MIPSEL64N32",
        "SCMP_ARCH_PPC",
        "SCMP_ARCH_PPC64",
        "SCMP_ARCH_PPC64LE",
        "SCMP_ARCH_RISCV64",
        "SCMP_ARCH_S390",
        "SCMP_ARCH_S390X",
        "SCMP_ARCH_X32",
        "SCMP_ARCH_X86",
        "SCMP_ARCH_X86_64"
      ],
      "knownFlags": [
        "SECCOMP_FILTER_FLAG_TSYNC",
        "SECCOMP_FILTER_FLAG_SPEC_ALLOW",
        "SECCOMP_FILTER_FLAG_LOG"
      ],
      "supportedFlags": [
        "SECCOMP_FILTER_FLAG_TSYNC",
        "SECCOMP_FILTER_FLAG_SPEC_ALLOW",
        "SECCOMP_FILTER_FLAG_LOG"
      ]
    },
    "apparmor": {
      "enabled": true
    },
    "selinux": {
      "enabled": true
    },
    "intelRdt": {
      "enabled": true
    }
  },
  "annotations": {
    "io.github.seccomp.libseccomp.version": "2.5.4",
    "org.opencontainers.runc.checkpoint.enabled": "true",
    "org.opencontainers.runc.commit": "v1.1.0-534-g26851168",
    "org.opencontainers.runc.version": "1.1.0+dev"
  }
}