1# <a name="features" />Features Structure
2
3A [runtime](glossary.md#runtime) MAY provide a JSON structure about its implemented features to [runtime callers](glossary.md#runtime-caller).
4This JSON structure is called ["Features structure"](glossary.md#features-structure).
5
6The Features structure is irrelevant to the actual availability of the features in the host operating system.
7Hence, the content of the Features structure SHOULD be determined on the compilation time of the runtime, not on the execution time.
8
9All properties in the Features structure except `ociVersionMin` and `ociVersionMax` MAY either be absent or have the `null` value.
10The `null` value MUST NOT be confused with an empty value such as `0`, `false`, `""`, `[]`, and `{}`.
11
12## <a name="featuresSpecificationVersion" />Specification version
13
14* **`ociVersionMin`** (string, REQUIRED) The minimum recognized version of the Open Container Initiative Runtime Specification.
15 The runtime MUST accept this value as the [`ociVersion` property of `config.json`](config.md#specification-version).
16
17* **`ociVersionMax`** (string, REQUIRED) The maximum recognized version of the Open Container Initiative Runtime Specification.
18 The runtime MUST accept this value as the [`ociVersion` property of `config.json`](config.md#specification-version).
19 The value MUST NOT be less than the value of the `ociVersionMin` property.
20 The Features structure MUST NOT contain properties that are not defined in this version of the Open Container Initiative Runtime Specification.
21
22### Example
23```json
24{
25 "ociVersionMin": "1.0.0",
26 "ociVersionMax": "1.1.0"
27}
28```
29
30## <a name="featuresHooks" />Hooks
31* **`hooks`** (array of strings, OPTIONAL) The recognized names of the [hooks](config.md#hooks).
32 The runtime MUST support the elements in this array as the [`hooks` property of `config.json`](config.md#hooks).
33
34### Example
35```json
36"hooks": [
37 "prestart",
38 "createRuntime",
39 "createContainer",
40 "startContainer",
41 "poststart",
42 "poststop"
43]
44```
45
46## <a name="featuresMountOptions" />Mount Options
47
48* **`mountOptions`** (array of strings, OPTIONAL) The recognized names of the mount options, including options that might not be supported by the host operating system.
49 The runtime MUST recognize the elements in this array as the [`options` of `mounts` objects in `config.json`](config.md#mounts).
50 * Linux: this array SHOULD NOT contain filesystem-specific mount options that are passed to the [mount(2)][mount.2] syscall as `const void *data`.
51
52### Example
53
54```json
55"mountOptions": [
56 "acl",
57 "async",
58 "atime",
59 "bind",
60 "defaults",
61 "dev",
62 "diratime",
63 "dirsync",
64 "exec",
65 "iversion",
66 "lazytime",
67 "loud",
68 "mand",
69 "noacl",
70 "noatime",
71 "nodev",
72 "nodiratime",
73 "noexec",
74 "noiversion",
75 "nolazytime",
76 "nomand",
77 "norelatime",
78 "nostrictatime",
79 "nosuid",
80 "nosymfollow",
81 "private",
82 "ratime",
83 "rbind",
84 "rdev",
85 "rdiratime",
86 "relatime",
87 "remount",
88 "rexec",
89 "rnoatime",
90 "rnodev",
91 "rnodiratime",
92 "rnoexec",
93 "rnorelatime",
94 "rnostrictatime",
95 "rnosuid",
96 "rnosymfollow",
97 "ro",
98 "rprivate",
99 "rrelatime",
100 "rro",
101 "rrw",
102 "rshared",
103 "rslave",
104 "rstrictatime",
105 "rsuid",
106 "rsymfollow",
107 "runbindable",
108 "rw",
109 "shared",
110 "silent",
111 "slave",
112 "strictatime",
113 "suid",
114 "symfollow",
115 "sync",
116 "tmpcopyup",
117 "unbindable"
118]
119```
120
121
122## <a name="featuresPlatformSpecificFeatures" />Platform-specific features
123
124* **`linux`** (object, OPTIONAL) [Linux-specific features](features-linux.md).
125 This MAY be set if the runtime supports `linux` platform.
126
127## <a name="featuresAnnotations" />Annotations
128
129**`annotations`** (object, OPTIONAL) contains arbitrary metadata of the runtime.
130This information MAY be structured or unstructured.
131Annotations MUST be a key-value map that follows the same convention as the Key and Values of the [`annotations` property of `config.json`](config.md#annotations).
132However, annotations do not need to contain the possible values of the [`annotations` property of `config.json`](config.md#annotations).
133The current version of the spec do not provide a way to enumerate the possible values of the [`annotations` property of `config.json`](config.md#annotations).
134
135### Example
136```json
137"annotations": {
138 "org.opencontainers.runc.checkpoint.enabled": "true",
139 "org.opencontainers.runc.version": "1.1.0"
140}
141```
142
143# Example
144
145Here is a full example for reference.
146
147```json
148{
149 "ociVersionMin": "1.0.0",
150 "ociVersionMax": "1.1.0-rc.2",
151 "hooks": [
152 "prestart",
153 "createRuntime",
154 "createContainer",
155 "startContainer",
156 "poststart",
157 "poststop"
158 ],
159 "mountOptions": [
160 "async",
161 "atime",
162 "bind",
163 "defaults",
164 "dev",
165 "diratime",
166 "dirsync",
167 "exec",
168 "iversion",
169 "lazytime",
170 "loud",
171 "mand",
172 "noatime",
173 "nodev",
174 "nodiratime",
175 "noexec",
176 "noiversion",
177 "nolazytime",
178 "nomand",
179 "norelatime",
180 "nostrictatime",
181 "nosuid",
182 "nosymfollow",
183 "private",
184 "ratime",
185 "rbind",
186 "rdev",
187 "rdiratime",
188 "relatime",
189 "remount",
190 "rexec",
191 "rnoatime",
192 "rnodev",
193 "rnodiratime",
194 "rnoexec",
195 "rnorelatime",
196 "rnostrictatime",
197 "rnosuid",
198 "rnosymfollow",
199 "ro",
200 "rprivate",
201 "rrelatime",
202 "rro",
203 "rrw",
204 "rshared",
205 "rslave",
206 "rstrictatime",
207 "rsuid",
208 "rsymfollow",
209 "runbindable",
210 "rw",
211 "shared",
212 "silent",
213 "slave",
214 "strictatime",
215 "suid",
216 "symfollow",
217 "sync",
218 "tmpcopyup",
219 "unbindable"
220 ],
221 "linux": {
222 "namespaces": [
223 "cgroup",
224 "ipc",
225 "mount",
226 "network",
227 "pid",
228 "user",
229 "uts"
230 ],
231 "capabilities": [
232 "CAP_CHOWN",
233 "CAP_DAC_OVERRIDE",
234 "CAP_DAC_READ_SEARCH",
235 "CAP_FOWNER",
236 "CAP_FSETID",
237 "CAP_KILL",
238 "CAP_SETGID",
239 "CAP_SETUID",
240 "CAP_SETPCAP",
241 "CAP_LINUX_IMMUTABLE",
242 "CAP_NET_BIND_SERVICE",
243 "CAP_NET_BROADCAST",
244 "CAP_NET_ADMIN",
245 "CAP_NET_RAW",
246 "CAP_IPC_LOCK",
247 "CAP_IPC_OWNER",
248 "CAP_SYS_MODULE",
249 "CAP_SYS_RAWIO",
250 "CAP_SYS_CHROOT",
251 "CAP_SYS_PTRACE",
252 "CAP_SYS_PACCT",
253 "CAP_SYS_ADMIN",
254 "CAP_SYS_BOOT",
255 "CAP_SYS_NICE",
256 "CAP_SYS_RESOURCE",
257 "CAP_SYS_TIME",
258 "CAP_SYS_TTY_CONFIG",
259 "CAP_MKNOD",
260 "CAP_LEASE",
261 "CAP_AUDIT_WRITE",
262 "CAP_AUDIT_CONTROL",
263 "CAP_SETFCAP",
264 "CAP_MAC_OVERRIDE",
265 "CAP_MAC_ADMIN",
266 "CAP_SYSLOG",
267 "CAP_WAKE_ALARM",
268 "CAP_BLOCK_SUSPEND",
269 "CAP_AUDIT_READ",
270 "CAP_PERFMON",
271 "CAP_BPF",
272 "CAP_CHECKPOINT_RESTORE"
273 ],
274 "cgroup": {
275 "v1": true,
276 "v2": true,
277 "systemd": true,
278 "systemdUser": true,
279 "rdma": true
280 },
281 "seccomp": {
282 "enabled": true,
283 "actions": [
284 "SCMP_ACT_ALLOW",
285 "SCMP_ACT_ERRNO",
286 "SCMP_ACT_KILL",
287 "SCMP_ACT_KILL_PROCESS",
288 "SCMP_ACT_KILL_THREAD",
289 "SCMP_ACT_LOG",
290 "SCMP_ACT_NOTIFY",
291 "SCMP_ACT_TRACE",
292 "SCMP_ACT_TRAP"
293 ],
294 "operators": [
295 "SCMP_CMP_EQ",
296 "SCMP_CMP_GE",
297 "SCMP_CMP_GT",
298 "SCMP_CMP_LE",
299 "SCMP_CMP_LT",
300 "SCMP_CMP_MASKED_EQ",
301 "SCMP_CMP_NE"
302 ],
303 "archs": [
304 "SCMP_ARCH_AARCH64",
305 "SCMP_ARCH_ARM",
306 "SCMP_ARCH_MIPS",
307 "SCMP_ARCH_MIPS64",
308 "SCMP_ARCH_MIPS64N32",
309 "SCMP_ARCH_MIPSEL",
310 "SCMP_ARCH_MIPSEL64",
311 "SCMP_ARCH_MIPSEL64N32",
312 "SCMP_ARCH_PPC",
313 "SCMP_ARCH_PPC64",
314 "SCMP_ARCH_PPC64LE",
315 "SCMP_ARCH_RISCV64",
316 "SCMP_ARCH_S390",
317 "SCMP_ARCH_S390X",
318 "SCMP_ARCH_X32",
319 "SCMP_ARCH_X86",
320 "SCMP_ARCH_X86_64"
321 ],
322 "knownFlags": [
323 "SECCOMP_FILTER_FLAG_TSYNC",
324 "SECCOMP_FILTER_FLAG_SPEC_ALLOW",
325 "SECCOMP_FILTER_FLAG_LOG"
326 ],
327 "supportedFlags": [
328 "SECCOMP_FILTER_FLAG_TSYNC",
329 "SECCOMP_FILTER_FLAG_SPEC_ALLOW",
330 "SECCOMP_FILTER_FLAG_LOG"
331 ]
332 },
333 "apparmor": {
334 "enabled": true
335 },
336 "selinux": {
337 "enabled": true
338 },
339 "intelRdt": {
340 "enabled": true
341 }
342 },
343 "annotations": {
344 "io.github.seccomp.libseccomp.version": "2.5.4",
345 "org.opencontainers.runc.checkpoint.enabled": "true",
346 "org.opencontainers.runc.commit": "v1.1.0-534-g26851168",
347 "org.opencontainers.runc.version": "1.1.0+dev"
348 }
349}
350```
351
352[mount.2]: https://man7.org/linux/man-pages/man2/mount.2.html
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