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*: Remove hooks
This drops all instances (outside the ChangeLog) turned up by case-insensitive searches for 'hook'. The desire to drop hooks has been around for a while now [1], but it took a while to land a create/start split. By the time that split did land, dropping hooks was still part of its motivation [2]. Hooks are hard to support robustly [3], and after the create/start split, callers can do whatever they like at those times without having to go through the runtime [4]. There is still a use-case for folks who prefer the old all-in-one UX, but we can support those folks with a higher-level wrapper built on hookless create/start primatives [5]. There was some last-minute discussion of pre-pivot mount propagation needing pre-start hooks [6], but that use case can be addressed by manipulating the mounts array [7]. With those arguments in place, the consensus at today's meeting seemed in favor of removing hooks from the spec [8]. [1]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-10-28-17.02.log.html#l-71 <wking> if you have a distinct create operation, you can drop the pre-start hooks, which makes a simpler spec [2]: #384 Subject: Split create and start In the topic post: > # Motivating usecases: > > * to simplify the flows/interaction patterns by removing hooks, > but still allow for the same functionality [3]: #265 Subject: runtime-config: Require serial hook execution [4]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-03-24.log.html#t2016-03-24T18:56:15 <vishh> mrunalp: How do I run http hooks? I need a binary wrapper to execute http hooks [5]: https://groups.google.com/a/opencontainers.org/d/msg/dev/Y7p6YW8zr4s/OVaAI_WDBAAJ Subject: Re: Hooks and all-in-one operation Date: Wed, 1 Jun 2016 11:49:07 -0700 Message-ID: <[email protected]> [6]: #384 (comment) Subject: Split create and start [7]: #384 (comment) Subject: Split create and start [8]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-06-01-17.01.log.html#l-83 Signed-off-by: W. Trevor King <[email protected]>
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‎README.md‎

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#### Application Bundle Builders
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Application bundle builders can create a [bundle](bundle.md) directory that includes all of the files required for launching an application as a container.
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The bundle contains an OCI [configuration file](config.md) where the builder can specify host-independent details such as [which executable to launch](config.md#process-configuration) and host-specific settings such as [mount](config.md#mounts) locations, [hook](config.md#hooks) paths, Linux [namespaces](config-linux.md#namespaces) and [cgroups](config-linux.md#control-groups).
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The bundle contains an OCI [configuration file](config.md) where the builder can specify host-independent details such as [which executable to launch](config.md#process-configuration) and host-specific settings such as [mount](config.md#mounts) locations, Linux [namespaces](config-linux.md#namespaces) and [cgroups](config-linux.md#control-groups).
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Because the configuration includes host-specific settings, application bundle directories copied between two hosts may require configuration adjustments.
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#### Hook Developers
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[Hook](config.md#hooks) developers can extend the functionality of an OCI-compliant runtime by hooking into a container's lifecycle with an external application.
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Example use cases include sophisticated network configuration, volume garbage collection, etc.
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#### Runtime Developers
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Runtime developers can build runtime implementations that run OCI-compliant bundles and container configuration, containing low-level OS and host specific details, on a particular platform.

‎ROADMAP.md‎

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* Linux
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*Owner:* robdolinms as lead coordinator
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### Full Lifecycle Hooks
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Ensure that we have lifecycle hooks in the correct places with full coverage over the container lifecycle.
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Will probably go away with Vish's work on splitting create and start, and if we have exec.
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*Owner:*

‎config.md‎

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}
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```
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## Hooks
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Lifecycle hooks allow custom events for different points in a container's runtime.
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Presently there are `Prestart`, `Poststart` and `Poststop`.
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* [`Prestart`](#prestart) is a list of hooks to be run before the container process is executed
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* [`Poststart`](#poststart) is a list of hooks to be run immediately after the container process is started
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* [`Poststop`](#poststop) is a list of hooks to be run after the container process exits
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Hooks allow one to run code before/after various lifecycle events of the container.
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Hooks MUST be called in the listed order.
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The state of the container is passed to the hooks over stdin, so the hooks could get the information they need to do their work.
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Hook paths are absolute and are executed from the host's filesystem in the [runtime namespace][runtime-namespace].
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### Prestart
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The pre-start hooks are called after the container process is spawned, but before the user supplied command is executed.
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They are called after the container namespaces are created on Linux, so they provide an opportunity to customize the container.
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In Linux, for e.g., the network namespace could be configured in this hook.
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If a hook returns a non-zero exit code, then an error including the exit code and the stderr is returned to the caller and the container is torn down.
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### Poststart
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The post-start hooks are called after the user process is started.
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For example this hook can notify user that real process is spawned.
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If a hook returns a non-zero exit code, then an error is logged and the remaining hooks are executed.
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### Poststop
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The post-stop hooks are called after the container process is stopped.
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Cleanup or debugging could be performed in such a hook.
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If a hook returns a non-zero exit code, then an error is logged and the remaining hooks are executed.
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### Example
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```json
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"hooks" : {
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"prestart": [
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{
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"path": "/usr/bin/fix-mounts",
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"args": ["fix-mounts", "arg1", "arg2"],
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"env": [ "key1=value1"]
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},
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{
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"path": "/usr/bin/setup-network"
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}
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],
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"poststart": [
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{
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"path": "/usr/bin/notify-start",
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"timeout": 5
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}
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],
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"poststop": [
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{
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"path": "/usr/sbin/cleanup.sh",
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"args": ["cleanup.sh", "-f"]
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}
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]
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}
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```
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`path` is required for a hook.
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`args` and `env` are optional.
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`timeout` is the number of seconds before aborting the hook.
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The semantics are the same as `Path`, `Args` and `Env` in [golang Cmd](https://golang.org/pkg/os/exec/#Cmd).
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## Annotations
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This OPTIONAL property contains arbitrary metadata for the container.
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]
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}
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],
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"hooks": {
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"prestart": [
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{
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"path": "/usr/bin/fix-mounts",
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"args": [
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"fix-mounts",
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"arg1",
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"arg2"
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],
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"env": [
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"key1=value1"
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]
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},
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{
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"path": "/usr/bin/setup-network"
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}
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],
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"poststart": [
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{
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"path": "/usr/bin/notify-start",
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"timeout": 5
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}
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],
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"poststop": [
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{
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"path": "/usr/sbin/cleanup.sh",
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"args": [
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"cleanup.sh",
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"-f"
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]
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}
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]
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},
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"linux": {
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"devices": [
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{

‎runtime.md‎

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Deleting a container MUST delete the resources that were created during the `create` step.
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Note that resources associated with the container, but not created by this container, MUST NOT be deleted.
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Once a container is deleted its ID MAY be used by a subsequent container.
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## Hooks
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Many of the operations specified in this specification have "hooks" that allow for additional actions to be taken before or after each operation.
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See [runtime configuration for hooks](./config.md#hooks) for more information.

‎schema/defs.json‎

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"Env": {
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"$ref": "#/definitions/ArrayOfStrings"
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},
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"Hook": {
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"properties": {
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"path": {
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"$ref": "#/definitions/FilePath"
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},
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"args": {
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"$ref": "#/definitions/ArrayOfStrings"
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},
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"env": {
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"$ref": "#/definitions/Env"
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}
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}
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},
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"ArrayOfHooks": {
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"type": "array",
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"items": {
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"$ref": "#/definitions/Hook"
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}
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},
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"IDMapping": {
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"properties": {
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"hostID": {

‎schema/schema.json‎

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"id": "https://opencontainers.org/schema/bundle/ociVersion",
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"type": "string"
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},
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"hooks": {
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"id": "https://opencontainers.org/schema/bundle/hooks",
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"type": "object",
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"properties": {
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"prestart": {
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"$ref": "defs.json#/definitions/ArrayOfHooks"
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},
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"poststart": {
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"$ref": "defs.json#/definitions/ArrayOfHooks"
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},
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"poststop": {
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"$ref": "defs.json#/definitions/ArrayOfHooks"
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}
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}
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},
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"annotations": {
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"id": "https://opencontainers.org/schema/bundle/annotations",
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"oneOf": [
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"process",
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"root",
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"hostname",
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"mounts",
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"hooks"
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"mounts"
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]
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}

‎specs-go/config.go‎

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Hostname string `json:"hostname,omitempty"`
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// Mounts profile configuration for adding mounts to the container's filesystem.
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Mounts []Mount `json:"mounts,omitempty"`
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// Hooks are the commands run at various lifecycle events of the container.
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Hooks Hooks `json:"hooks"`
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// Annotations is an unstructured key value map that may be set by external tools to store and retrieve arbitrary metadata.
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Annotations map[string]string `json:"annotations,omitempty"`
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Options []string `json:"options,omitempty"`
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}
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// Hook specifies a command that is run at a particular event in the lifecycle of a container
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type Hook struct {
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Path string `json:"path"`
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Args []string `json:"args,omitempty"`
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Env []string `json:"env,omitempty"`
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Timeout *int `json:"timeout,omitempty"`
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}
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// Hooks for container setup and teardown
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type Hooks struct {
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// Prestart is a list of hooks to be run before the container process is executed.
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// On Linux, they are run after the container namespaces are created.
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Prestart []Hook `json:"prestart,omitempty"`
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// Poststart is a list of hooks to be run after the container process is started.
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Poststart []Hook `json:"poststart,omitempty"`
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// Poststop is a list of hooks to be run after the container process exits.
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Poststop []Hook `json:"poststop,omitempty"`
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}
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// Linux contains platform specific configuration for Linux based containers.
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type Linux struct {
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// UIDMapping specifies user mappings for supporting user namespaces on Linux.

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