cat_gateway/service/utilities/middleware/
schema_validation.rs

1//! Middleware to verify the status of the last DB schema version validation.
2//!
3//! If a mismatch is detected, the middleware returns an error with `ServiceUnavailable`
4//! status code (503). Otherwise, the middleware calls and returns the wrapped endpoint's
5//! response.
6//!
7//! This middleware checks the `State.schema_version_status` value, if it is Ok,
8//! the wrapped endpoint is called and its response is returned.
9
10use poem::{http::StatusCode, Endpoint, EndpointExt, Middleware, Request, Result};
11use tracing::error;
12
13use crate::{
14    db::event::{EventDB, EventDBConnectionError},
15    service::utilities::health::set_event_db_liveness,
16};
17
18/// A middleware that raises an error  with `ServiceUnavailable` and 503 status code
19/// if a DB schema version mismatch is found the existing `State`.
20pub(crate) struct SchemaVersionValidation;
21
22impl<E: Endpoint> Middleware<E> for SchemaVersionValidation {
23    type Output = SchemaVersionValidationImpl<E>;
24
25    fn transform(&self, ep: E) -> Self::Output {
26        SchemaVersionValidationImpl { ep }
27    }
28}
29
30/// The new endpoint type generated by the `SchemaVersionValidation`.
31pub(crate) struct SchemaVersionValidationImpl<E> {
32    /// Endpoint wrapped by the middleware.
33    ep: E,
34}
35
36impl<E: Endpoint> Endpoint for SchemaVersionValidationImpl<E> {
37    type Output = E::Output;
38
39    async fn call(&self, req: Request) -> Result<Self::Output> {
40        // Check if the inner schema version status is set to `Mismatch`,
41        // if so, return the `StatusCode::SERVICE_UNAVAILABLE` code.
42        if let Err(e) = EventDB::schema_version_check().await {
43            if e.is::<EventDBConnectionError>() {
44                set_event_db_liveness(false);
45                error!("Event DB is disconnected. Liveness set to false");
46            } else {
47                error!("Schema version check error: {e:?}");
48            }
49            return Err(StatusCode::SERVICE_UNAVAILABLE.into());
50        }
51        // Calls the endpoint with the request, and returns the response.
52        self.ep.call(req).await
53    }
54}
55
56/// A function that wraps an endpoint with the `SchemaVersionValidation`.
57///
58/// This function is convenient to use with `poem-openapi` [operation parameters](https://docs.rs/poem-openapi/latest/poem_openapi/attr.OpenApi.html#operation-parameters) via the
59/// `transform` attribute.
60pub(crate) fn schema_version_validation(ep: impl Endpoint) -> impl Endpoint {
61    ep.with(SchemaVersionValidation)
62}
cat_gateway/service/utilities/middleware/schema_validation.rs

cat_gateway/service/utilities/middleware/
schema_validation.rs
