Crate k8s_openapi

Expand description

Bindings for the Kubernetes client API, generated from the OpenAPI spec.

Each supported version of Kubernetes is represented by a feature name (like v1_9). Only one such feature can be enabled at a time.

These docs have been generated with the v1_28 feature enabled. To see docs for one of the other supported versions, please generate the docs locally with cargo doc --features 'v1_<>'

Examples

Resources

This example creates an instance of api::core::v1::PodSpec with no other properties set, and pretty-prints it.

use k8s_openapi::api::core::v1 as api;

fn main() {
    let pod_spec: api::PodSpec = Default::default();
    println!("{pod_spec:#?}");
}

This crate contains several v1_* features. Enabling one of the v1_* features selects which version of the Kubernetes API server this crate should target. For example, enabling the v1_23 feature means the crate will only contain the API exposed by Kubernetes 1.23. It will not expose API that were removed in 1.23 or earlier, nor any API added in 1.24 or later.

One and only one of the v1_* features must be enabled at the same time, otherwise the crate will not compile. This ensures that all crates in the crate graph use the same types. If it was possible for one library crate to use api::core::v1::Pod corresponding to v1.50 and another to use the type corresponding to v1.51, an application would not be able to use the same Pod value with both.

Thus, it is recommended that only application crates must enable one of the v1_* features, corresponding to the version of Kubernetes that the application wants to support.

# For application crates

[dependencies]
k8s-openapi = { version = "...", features = ["v1_50"] }

If you’re writing a library crate, your crate must not enable any features of k8s-openapi directly. The choice of which feature to enable must be left to any application crates that use your library. This ensures that all k8s-openapi-using dependencies in that application crate’s dependency graph use the same set of k8s-openapi types and are interoperable.

If your library crate has tests or examples, you should also add a dev-dependency on k8s-openapi in addition to the direct dependency, and enable a version feature only for that dev-dependency.

# For library crates

[dependencies]
k8s-openapi = "..."

[dev-dependencies]
k8s-openapi = { version = "...", features = ["v1_50"] }

However, commands like cargo check and cargo doc do not build dev dependencies, so they will not enable the feature and will fail to build. There are two ways you can resolve this:

Add a feature to your library that enables one of the k8s-openapi v1_* features, and then remember to enable this feature when running such commands.
```
[features]
__check = ["k8s-openapi/v1_50"]
```
```
$ cargo check --features __check
```
Define the K8S_OPENAPI_ENABLED_VERSION env var when running such commands:
```
$ K8S_OPENAPI_ENABLED_VERSION=1.50 cargo check
```

Conditional compilation

As the previous section explained, library crates must not enable any version features in their k8s-openapi dependency. However, your library crate may need to know about which version gets selected eventually.

For example:

Your crate creates a PodSpec and wants to set the host_users field. This field is only available in Kubernetes 1.25+, so you want your crate to fail to compile if a lower feature was enabled.
Your crate creates a PodSpec and wants to set the host_users field, but it’s okay to not set it when compiling for older versions.

There are two ways for your crate to determine which feature of k8s-openapi is enabled:

The k8s-openapi crate exports k8s_if_* macros, which either expand to their contents or don’t. See the docs of the macros for more details.

With these macros, the two cases above would be solved like this:

// The compile_error!() is only emitted if 1.24 or lower is selected.
k8s_openapi::k8s_if_le_1_24! {
    compile_error!("This crate requires the v1_25 (or higher) feature to be enabled on the k8s-openapi crate.");
}

...

let pod_spec = k8s_openapi::api::core::v1::PodSpec {
    host_users: ...,
    ...
};

let mut pod_spec = k8s_openapi::api::core::v1::PodSpec {
    ...
};

k8s_openapi::k8s_if_ge_1_25! {
    pod_spec.host_users = ...;
}

The k8s-openapi crate emits the selected version number as metadata that your crate can read in a build script from the DEP_K8S_OPENAPI_*_VERSION env var.

// Your crate's build.rs

fn main() {
    let k8s_openapi_version: u32 =
        std::env::vars_os()
        .find_map(|(key, value)| {
            let key = key.into_string().ok()?;
            if key.starts_with("DEP_K8S_OPENAPI_") && key.ends_with("_VERSION") {
                let value = value.into_string().ok()?;
                Some(value)
            }
            else {
                None
            }
        }).expect("DEP_K8S_OPENAPI_*_VERSION must have been set by k8s-openapi")
        .parse().expect("DEP_K8S_OPENAPI_*_VERSION is malformed");

    // k8s_openapi_version has the format 0x00_MM_NN_00.
    //
    // - MM is the major version.
    // - NN is the minor version.
    //
    // Thus, if the v1_25 feature was enabled, k8s_openapi_version would be 0x00_01_19_00

    // The build script can now do arbitrary things with the information.
    // For example, it could define custom cfgs:
    if k8s_openapi_version >= 0x00_01_19_00 {
        println!(r#"cargo:rustc-cfg=k8s_pod_spec_supports_host_users"#);
    }

    // or emit new source code files under OUT_DIR, or anything else a build script can do.
}

With these cfgs, the two cases above would be solved like this:

// The compile_error!() is only emitted if 1.24 or lower is selected.
#[cfg(not(k8s_pod_spec_supports_host_users))]
compile_error!("This crate requires the v1_25 (or higher) feature to be enabled on the k8s-openapi crate.");

...

let pod_spec = k8s_openapi::api::core::v1::PodSpec {
    host_users: ...,
    ...
};

let pod_spec = k8s_openapi::api::core::v1::PodSpec {
    #[cfg(not(k8s_pod_spec_supports_host_users))]
    host_users: ...,
    ...
};

Note that both approaches require your crate to have a direct dependency on the k8s-openapi crate. Neither approach is available if your crate only has a transitive dependency on the k8s-openapi crate.

The macros approach is easier to use since it doesn’t require a build script.

The build script method lets you emit arbitrary cfgs, emit arbitrary source code, and generally gives you more options, at the cost of needing a build script. cfg()s can be used in places where macros cannot, such as how the second example above shows it being used on a single field in a struct literal.

Custom resource definitions

The k8s-openapi-derive crate provides a custom derive for generating clientsets for custom resources. See that crate’s docs for more information.

Re-exports

pub use chrono;
pub use serde;
pub use serde_json;
pub use serde_value;

Modules

api
apiextensions_apiserver
apimachinery
kube_aggregator
merge_strategies
Strategies for merging collections.

Macros

k8s_if_1_22
This macro evaluates to its contents if the v1_22 feature is enabled, otherwise it evaluates to nothing.
k8s_if_1_23
This macro evaluates to its contents if the v1_23 feature is enabled, otherwise it evaluates to nothing.
k8s_if_1_24
This macro evaluates to its contents if the v1_24 feature is enabled, otherwise it evaluates to nothing.
k8s_if_1_25
This macro evaluates to its contents if the v1_25 feature is enabled, otherwise it evaluates to nothing.
k8s_if_1_26
This macro evaluates to its contents if the v1_26 feature is enabled, otherwise it evaluates to nothing.
k8s_if_1_27
This macro evaluates to its contents if the v1_27 feature is enabled, otherwise it evaluates to nothing.
k8s_if_1_28
This macro evaluates to its contents if the v1_28 feature is enabled, otherwise it evaluates to nothing.
k8s_if_ge_1_22
This macro evaluates to its contents if the v1_22 or higher feature is enabled, otherwise it evaluates to nothing.
k8s_if_ge_1_23
This macro evaluates to its contents if the v1_23 or higher feature is enabled, otherwise it evaluates to nothing.
k8s_if_ge_1_24
This macro evaluates to its contents if the v1_24 or higher feature is enabled, otherwise it evaluates to nothing.
k8s_if_ge_1_25
This macro evaluates to its contents if the v1_25 or higher feature is enabled, otherwise it evaluates to nothing.
k8s_if_ge_1_26
This macro evaluates to its contents if the v1_26 or higher feature is enabled, otherwise it evaluates to nothing.
k8s_if_ge_1_27
This macro evaluates to its contents if the v1_27 or higher feature is enabled, otherwise it evaluates to nothing.
k8s_if_ge_1_28
This macro evaluates to its contents if the v1_28 or higher feature is enabled, otherwise it evaluates to nothing.
k8s_if_le_1_22
This macro evaluates to its contents if the v1_22 or lower feature is enabled, otherwise it evaluates to nothing.
k8s_if_le_1_23
This macro evaluates to its contents if the v1_23 or lower feature is enabled, otherwise it evaluates to nothing.
k8s_if_le_1_24
This macro evaluates to its contents if the v1_24 or lower feature is enabled, otherwise it evaluates to nothing.
k8s_if_le_1_25
This macro evaluates to its contents if the v1_25 or lower feature is enabled, otherwise it evaluates to nothing.
k8s_if_le_1_26
This macro evaluates to its contents if the v1_26 or lower feature is enabled, otherwise it evaluates to nothing.
k8s_if_le_1_27
This macro evaluates to its contents if the v1_27 or lower feature is enabled, otherwise it evaluates to nothing.
k8s_if_le_1_28
This macro evaluates to its contents if the v1_28 or lower feature is enabled, otherwise it evaluates to nothing.
k8s_match
A macro that emits a match expr with the given test expression and arms. The match arms can be annotated with the other conditional compilation macros in this crate so that they’re only emitted if the predicate is true.

Structs

ByteString
A wrapper around a list of bytes.
ClusterResourceScope
Indicates that a Resource is cluster-scoped.
List
List is a list of resources.
NamespaceResourceScope
Indicates that a Resource is namespace-scoped.
SubResourceScope
Indicates that a Resource is neither cluster-scoped nor namespace-scoped.

Traits

DeepMerge
A trait applies to types that support deep merging.
ListableResource
A trait applied to all Kubernetes resources that can be part of a corresponding list.
Metadata
A trait applied to all Kubernetes resources that have metadata.
Resource
A trait applied to all Kubernetes resources.
ResourceScope
The scope of a Resource.

Functions

api_version
Extracts the API version of the given resource value.
group
Extracts the group of the given resource value.
kind
Extracts the kind of the given resource value.
version
Extracts the version of the given resource value.