# keldra
The official Rust client for Keldra. It provides authenticated object upload
helpers and the complete generated Keldra 0.18 v1 protocol, including object,
authorization, administration, cluster-wide index, accounting, and PersonalDB
clients.
## Install
```sh
cargo add keldra@0.18.0
cargo add tokio --features macros,rt-multi-thread
```
## Connect and read an object head
Set `KELDRA_ENDPOINT`, `KELDRA_CLIENT_ID`, and
`KELDRA_CLIENT_SECRET_FILE` (a mode-`0600` file), then run:
```rust,no_run
use keldra::v1::{HeadObjectRequest, ObjectAddress, object_head};
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
let mut client = keldra::connect_with_credentials(
std::env::var("KELDRA_ENDPOINT")?,
std::env::var("KELDRA_CLIENT_ID")?,
std::fs::read_to_string(std::env::var("KELDRA_CLIENT_SECRET_FILE")?)?,
)
.await?;
let head = client
.head_object(HeadObjectRequest {
address: Some(ObjectAddress {
tenant: "example".into(),
bucket: "documents".into(),
path: "reports/annual.pdf".into(),
}),
})
.await?
.into_inner();
match head.state {
Some(object_head::State::Present(object)) => {
println!("object version: {}", object.version);
}
Some(object_head::State::Deleted(object)) => {
println!("deleted at version: {}", object.version);
}
Some(object_head::State::NeverExisted(_)) => println!("object does not exist"),
None => println!("no object state returned"),
}
Ok(())
}
```
Use an HTTPS endpoint when exchanging client credentials.
## Clone bytes or link a mutable name
`CloneObject` creates an independent destination version which initially shares
the source version's existing payload bytes. `LinkObject` instead creates a
transparent name for the same mutable target: writes through either path update
the target, and unlinking removes only the link.
```rust,no_run
use keldra::v1::{
CloneObjectRequest, Durability, LinkObjectRequest, ObjectAddress,
PutIfAbsentOperation, UnlinkObjectRequest, clone_object_request,
};
# async fn aliases(client: &mut keldra::RawClient) -> Result<(), tonic::Status> {
let target = ObjectAddress {
tenant: "example".into(),
bucket: "documents".into(),
path: "reports/annual.pdf".into(),
};
let clone = ObjectAddress {
path: "archives/annual.pdf".into(),
..target.clone()
};
client.clone_object(CloneObjectRequest {
source: Some(target.clone()),
source_version: 41,
destination: Some(clone),
command_id: "clone-annual-41".into(),
durability: Durability::Replicated as i32,
operation: Some(clone_object_request::Operation::PutIfAbsent(
PutIfAbsentOperation {},
)),
}).await?;
let link = ObjectAddress {
path: "reports/latest.pdf".into(),
..target.clone()
};
client.link_object(LinkObjectRequest {
link: Some(link.clone()),
target: Some(target),
command_id: "link-latest".into(),
durability: Durability::Replicated as i32,
}).await?;
client.unlink_object(UnlinkObjectRequest {
link: Some(link),
command_id: "unlink-latest".into(),
durability: Durability::Replicated as i32,
}).await?;
# Ok(())
# }
```
Clone and link require cluster protocol/storage capability `1/1`. Operators must
start 0.18 on fresh authoritative and derived-index volumes and confirm that the
fresh cluster reports active capability `1/1` before applications invoke them.
## Define a typed index safely
Typed JSON fields expose only capabilities valid for their logical type. The
builder below creates exact keyword postings and numeric order doc values; an
invalid combination such as Boolean range search cannot be constructed.
```rust,no_run
use keldra::{DateField, KeywordField, TypedJsonIndexBuilder};
# fn definition() -> Result<keldra::v1::CreateIndexRequest, Box<dyn std::error::Error + Send + Sync>> {
let modified = DateField::single("modified_at", "/modified_at")
.range()
.order();
let newest_first = modified.descending();
let request = TypedJsonIndexBuilder::new("documents", "published")
.path_prefix("articles/")
.content_type("application/json")
.field(KeywordField::single("status", "/status").exact())
.field(modified)
.physical_order([newest_first])
.finish("create-published-index")?;
# let _ = request;
# Ok(())
# }
```
Pass the request to `IndexServiceClient::create_index`. Query hits return the
ordinary object address and exact version; fetch selected source objects with
`GetObject` or `BatchGet`.
`TypedJsonIndexBuilder::finish` explicitly selects application result
authorization. Existing application-scoped queries therefore set
`QueryIndexRequest.authorization_subject` to `None`. To enforce an end-user
realm, replace the request's `result_authorization` with an
`IndexResultAuthorization` whose policy is `Policy::Realm` before `CreateIndex`
and pass a concrete object `Subject` on every query; see the repository
README's custom-realm example. Realm authorization intersects the authenticated
application's access and never grants the application additional object access.
The concrete builders are `BooleanField`, `SignedIntegerField`,
`UnsignedIntegerField`, `FloatField`, `KeywordField`, `TextField`, and
`DateField`. Date fields use ISO-8601 by default; pass a pattern created by
`DateFormat::strftime(...)` to `DateField::format(...)` for one validated custom
format. Offset-less inputs are UTC and precision finer than milliseconds is
rejected. Date exact/range/order/facet operations use signed Unix epoch
milliseconds internally, while facet values are returned in the configured
format without storing source strings. Their
available methods mirror Keldra's native capabilities: exact matching, keyword
prefix and range matching, numeric ranges, ordering, facets, numeric
aggregates, and analyzed full-text search. A field emits only the index
components required by the methods selected on its builder. Multi-valued
keyword and numeric fields retain source multiplicity for aggregate operations,
while one document contributes at most once to each distinct facet bucket.
## Build bounded Boolean queries
`PredicateExpression` encodes canonical typed scalar values and constructs only
non-empty Boolean operators within Keldra's public 32-level/256-node bounds.
Facets, aggregates, ordering, pagination, and freshness remain ordinary public
query options and apply to the complete authorized Boolean match set.
```rust,no_run
use keldra::PredicateExpression;
use keldra::v1::{
IndexAggregateOperation, IndexAggregateRequest, IndexFacetRequest,
TypedJsonIndexQuery,
};
# fn query() -> Result<TypedJsonIndexQuery, Box<dyn std::error::Error + Send + Sync>> {
let runnable = PredicateExpression::all([
PredicateExpression::any([
PredicateExpression::equal("status", "pending")?,
PredicateExpression::equal("status", "retryable")?,
])?,
PredicateExpression::less_than_or_equal("due_at", 1_800_000_000_u64)?,
PredicateExpression::exists("deleted_at")?.negated()?,
])?;
let query = TypedJsonIndexQuery {
predicate: Some(runnable.into_proto()),
order: vec![],
facets: vec![IndexFacetRequest {
field: "status".into(),
limit: 10,
}],
aggregates: vec![IndexAggregateRequest {
field: "duration".into(),
operation: IndexAggregateOperation::Average as i32,
}],
};
# Ok(query)
# }
```
## Upload with compare-and-swap
`put_chunks` performs Keldra's `StartPut`, streaming `Put`, and `PutEnd` flow.
The operation below publishes only when version 41 is still current:
```rust,no_run
use keldra::v1::{
Durability, ObjectAddress, PutHeader, PutIfVersionOperation, put_header,
};
# async fn upload(
# client: &mut keldra::RawClient,
# ) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
let receipt = keldra::put_chunks(
client,
PutHeader {
address: Some(ObjectAddress {
tenant: "example".into(),
bucket: "documents".into(),
path: "reports/annual.pdf".into(),
}),
content_type: "application/pdf".into(),
command_id: "publish-annual-report".into(),
durability: Durability::Local as i32,
operation: Some(put_header::Operation::PutIfVersion(
PutIfVersionOperation {
expected_version: 41,
},
)),
},
vec![b"first chunk".to_vec(), b"second chunk".to_vec()],
)
.await?;
println!("published version: {}", receipt.version);
# Ok(())
# }
```
All generated clients and messages are available under `keldra::v1`.
Use `connect_channel` to share a transport; `object_client`, `index_client`,
`authz_client`, `administration_client`, and `personaldb_client` construct the
authenticated public service clients with the same bearer token.