[Merged by Bors] - Ensure that explicit YAML documents are generated for CRDs

[siegfriedweber]

Description

• YAML module added with a function to serialize a data structure as an explicit YAML document. The YAML documents generated by the functions in crd::CustomResourceExt are now explicit documents and can be safely concatenated to produce a YAML stream.
• serde_yaml 0.8.26 -> 0.9.9

CRDs can now safely be concatenated by using CustomResourceExt::print_yaml_schema in a row:

-//! use kube::CustomResourceExt;
+//! use stackable_operator::CustomResourceExt;

 //! let opts = Opts::from_args();
 //!
 //! match opts.command {
-//!     cli::Command::Crd => println!(
-//!         "{}{}",
-//!         serde_yaml::to_string(&FooCluster::crd())?,
-//!         serde_yaml::to_string(&BarCluster::crd())?,
-//!     ),
+//!     cli::Command::Crd => {
+//!         FooCluster::print_yaml_schema()?;
+//!         BarCluster::print_yaml_schema()?;
+//!     },
 //!     cli::Command::Run { .. } => {
 //!         // Run the operator
 //!     }

Hint: If this was the only usage of serde_yaml in an operator then it can be removed from the dependencies.

Review Checklist

• Code contains useful comments
• (Integration-)Test cases added (or not applicable)
• Documentation added (or not applicable)
• Changelog updated (or not applicable)
• Cargo.toml only contains references to git tags (not specific commits or branches)

Once the review is done, comment bors r+ (or bors merge) to merge. Further information

[nightkr]

Hm, does this come from serde_yaml? We might need to go back to the old tagging format somehow…

[nightkr]

dtolnay/serde-yaml#298

[siegfriedweber]

The proposed solution in serde_yaml:0.9.4 is to annotate every enum field with #[serde(with = "serde_yaml::with::singleton_map")], see dtolnay/serde-yaml#300.

But this solution does not work together with JsonSchema, see GREsau/schemars#89.

One workaround is to use the serde parameters serialize_with and deserialize_with:

#[serde(
    default,
    skip_serializing_if = "Option::is_none",
    serialize_with = "serde_yaml::with::singleton_map::serialize",
    deserialize_with = "serde_yaml::with::singleton_map::deserialize"
)]
pub connection: Option<S3ConnectionDef>,

This becomes quite verbose.

In which cases do the YAML tags actually pose a problem?

[siegfriedweber]

serde_yaml:0.9.9 introduced singleton_map_recursive which allows to serialize enums as YAML maps containing one entry in which the key identifies the variant name.

This is now used in stackable_operator::yaml::serialize_to_explicit_document. Further annotations are not necessary in the operators.

[maltesander]

Does it make sense to simply reexport serde_yaml here as well to have consistent versions?
In the OPA PR stackabletech/opa-operator#326 i think we have a problem with different versions (e.g. 0.8.25 in the operator-rs and 0.9 in OPA). The operator-rs has a YamlSerilizationError with source on the serde_yaml error which changed from 0.8 to 0.9.

[nightkr]

@maltesander I believe that usage falls away anyway, if you use the new helper? So you should be able to remove the serde_yaml dependency entirely.

[maltesander]

@maltesander I believe that usage falls away anyway, if you use the new helper? So you should be able to remove the serde_yaml dependency entirely.

Ok (did not check the PR), thats fine with me then.

[siegfriedweber]

We assume that the changes in serde_yaml, especially the generated YAML tags, have a high impact on a lot of projects and that there will adaptations in one of the next serde_yaml releases. So we decided to postpone this pull request until the next release and then reevaluate the situation.

[nightkr]

Nice!

[siegfriedweber]

bors merge

[bors]

Pull request successfully merged into main.

Build succeeded:

• All tests passed