Rationale
---------
Our CLI needs to be able to accept configuration as JSON and render configuration as JSON.
Protobufs technically have an official JSON encoding rule called 'jsonpb` but prost doesn't
offer native supprot for it.
`prost` allows us to specify arbitrary derive metadata to be added to generated
code. We emit the `serde` derive directives in the two packages that generate prost code
(`generated_types` and `google_types`).
We use the `serde(rename_all = "camelCase")` to approximate `jsonpb`.
We instruct `prost` to use `bytes::Bytes` for some types, hence we must turn on the `serde` feature
on the `bytes` dependency.
We also use json to serialize the output of the `database get` command, to showcase the feature
and get rid of a TODO. In a subsequent PR I'll teach `database create` (and the yet to be done `database update`) to accept an option JSON configuration body so we can configure partitioning, lifecycle, sharding etc rules etc.
Caveats
-------
This is not technically `jsonpb`. Main issues:
1. default values not omitted
2. no special rendering of special types like `google.protobuf.Any`
Future work
-----------
Figure out if we can get fully compliant `jsonpb`, or at least a decent approximation.
Effect
------
```console
$ cargo run -- database get foobar_weather
{
"name": "foobar_weather",
"partitionTemplate": {
"parts": [
{
"part": {
"time": "%Y-%m-%d %H:00:00"
}
}
]
},
"lifecycleRules": {
"mutableLingerSeconds": 0,
"mutableMinimumAgeSeconds": 0,
"mutableSizeThreshold": 0,
"bufferSizeSoft": 0,
"bufferSizeHard": 0,
"sortOrder": {
"order": 2,
"sort": {
"createdAtTime": {}
}
},
"dropNonPersisted": false,
"immutable": false
},
"walBufferConfig": null,
"shardConfig": {
"specificTargets": null,
"hashRing": null,
"ignoreErrors": false
}
}
```
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