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fix: Do not remove features cache if upstream goes away #362

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merged 4 commits into from
Dec 20, 2023
Merged

fix: Do not remove features cache if upstream goes away #362

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6c7337a
fix: Do not remove features cache if upstream goes away
chriswk Dec 19, 2023
3509e5f
cargo fix
chriswk Dec 19, 2023
06eb4d4
fix: Change to backoff when receiving NotFound
chriswk Dec 20, 2023
c5d119e
Updated test for feature_refresher
chriswk Dec 20, 2023
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20 changes: 10 additions & 10 deletions Cargo.lock
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10 changes: 5 additions & 5 deletions server/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ repository = "https://github.com/Unleash/unleash-edge"
version = "16.0.6"

[dependencies]
actix-cors = "0.6.4"
actix-cors = "0.6.5"
actix-http = { version = "3.4.0", features = ["compress-zstd", "rustls-0_21"] }
actix-middleware-etag = "0.3.0"
actix-service = "2.0.2"
Expand All @@ -26,7 +26,7 @@ anyhow = "1.0.75"
async-trait = "0.1.74"
chrono = { version = "0.4.31", features = ["serde"] }
cidr = "0.2.2"
clap = { version = "4.4.8", features = ["derive", "env"] }
clap = { version = "4.4.11", features = ["derive", "env"] }
clap-markdown = "0.1.3"
dashmap = "5.5.3"
futures = "0.3.29"
Expand Down Expand Up @@ -62,7 +62,7 @@ rustls-pemfile = "1.0.4"
serde = { version = "1.0.192", features = ["derive"] }
serde_json = "1.0.108"
serde_qs = { version = "0.12.0", features = ["actix4", "tracing"] }
shadow-rs = "0.24.1"
shadow-rs = { version = "0.25.0" }
tokio = { version = "1.34.0", features = [
"macros",
"rt-multi-thread",
Expand All @@ -75,7 +75,7 @@ ulid = "1.1.0"
unleash-types = { version = "0.10", features = ["openapi", "hashes"] }
unleash-yggdrasil = { version = "0.8.0" }
utoipa = { version = "4.1.0", features = ["actix_extras", "chrono"] }
utoipa-swagger-ui = { version = "4", features = ["actix-web"] }
utoipa-swagger-ui = { version = "5", features = ["actix-web"] }
[dev-dependencies]
actix-http = "3.4.0"
actix-http-test = "3.1.0"
Expand All @@ -89,4 +89,4 @@ testcontainers-modules = { version = "0.2.0", features = ["redis"] }
tracing-test = "0.2.4"

[build-dependencies]
shadow-rs = "0.24.1"
shadow-rs = "0.25.0"
2 changes: 1 addition & 1 deletion server/src/frontend_api.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -214,7 +214,7 @@ security(
)
)]
#[get("")]
#[instrument(skip(engine_cache, token_cache))]
#[instrument(skip(edge_token, req, engine_cache, token_cache))]
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async fn get_enabled_frontend(
edge_token: EdgeToken,
engine_cache: Data<DashMap<String, EngineState>>,
Expand Down
71 changes: 57 additions & 14 deletions server/src/http/feature_refresher.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ use actix_web::http::header::EntityTag;
use chrono::Utc;
use dashmap::DashMap;
use reqwest::StatusCode;
use tracing::{debug, info, warn};
use tracing::{debug, info};
use unleash_types::client_features::Segment;
use unleash_types::client_metrics::ClientApplication;
use unleash_types::{
Expand Down Expand Up @@ -376,11 +376,11 @@ impl FeatureRefresher {
self.backoff(&refresh.token);
}
_ => {
warn!("Couldn't refresh features, but will retry next go")
info!("Couldn't refresh features, but will retry next go")
}
},
FeatureError::AccessDenied => {
warn!("Token used to fetch features was Forbidden, will remove from list of refresh tasks");
info!("Token used to fetch features was Forbidden, will remove from list of refresh tasks");
self.tokens_to_refresh.remove(&refresh.token.token);
if !self.tokens_to_refresh.iter().any(|e| {
e.value().token.environment == refresh.token.environment
Expand All @@ -392,23 +392,15 @@ impl FeatureRefresher {
}
}
FeatureError::NotFound => {
warn!("Had a bad URL when trying to fetch features. Removing ourselves");
info!("Had a bad URL when trying to fetch features. Removing ourselves from the list of refresh tasks");
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What happens when upstream is back online? I think 404 response code depends on each server/LB implementation, but maybe one reason for 404 is no pods available in a k8s cluster.

If we consider the backoff implementation we did in the SDKs I think this is correct as it's aligned with that. I'm just wondering if this behavior changes when edge is still not ready (i.e. before receiving at least 1 successful response from upstream)

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This sounds relevant, but it's a little early for me to understand exactly what you're saying 🥱 Would you be willing to explain this comment a little more for me?

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@chriswk chriswk Dec 20, 2023 •
edited
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So, every time the same key gets used we do the evaluation in the following order

  1. Is key even allowed to access - this is stored in the TokenCache
    2a. We have equal or wider access to the token's environment already, if so, we should be able to get features from the feature cache
    2b We do not have equal or wider access, add the token to the list of tokens our FeatureRefresher cares about
  2. Once we have features, give them to Yggdrasil to build an EngineState
  3. Evaluate toggles if /api/frontend, return toggles if /api/client/features

What Gaston is worrying about is whether or not we repeat step 2, if upstream comes back online. From what I gather, we'll attempt to register it for refresh once every hour for normal tokens. I'm starting to think we should change the default here to 5 minutes or so.

For startup tokens, we try once every second until they achieve TokenStatus::Validated, then they too get moved into the refresh once per hour.

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Right, and by step 2, you're referring to

  1. Once we have features, give them to Yggdrasil to build an EngineState

Right? Or 2a/2b? Anyway, it sounds like you've got it covered?

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self.tokens_to_refresh.remove(&refresh.token.token);
if !self.tokens_to_refresh.iter().any(|e| {
e.value().token.environment == refresh.token.environment
}) {
let cache_key = cache_key(&refresh.token);
// No tokens left that access the environment of our current refresh. Deleting client features and engine cache
self.features_cache.remove(&cache_key);
self.engine_cache.remove(&cache_key);
}
}
}
}
EdgeError::ClientCacheError => {
warn!("Couldn't refresh features, but will retry next go")
info!("Couldn't refresh features, but will retry next go")
}
_ => warn!("Couldn't refresh features: {e:?}. Will retry next pass"),
_ => info!("Couldn't refresh features: {e:?}. Will retry next pass"),
}
}
}
Expand Down Expand Up @@ -448,6 +440,7 @@ mod tests {
use chrono::{Duration, Utc};
use dashmap::DashMap;
use reqwest::Url;
use tracing_test::traced_test;
use unleash_types::client_features::{ClientFeature, ClientFeatures};
use unleash_yggdrasil::EngineState;

Expand Down Expand Up @@ -898,6 +891,56 @@ mod tests {
assert!(feature_refresher.engine_cache.is_empty());
}

#[tokio::test]
#[traced_test]
pub async fn getting_404_removes_tokens_from_token_to_refresh_but_not_its_features() {
let mut token = EdgeToken::try_from("*:development.secret123".to_string()).unwrap();
token.status = Validated;
token.token_type = Some(TokenType::Client);
let token_cache = DashMap::default();
token_cache.insert(token.token.clone(), token.clone());
let upstream_features_cache: Arc<DashMap<String, ClientFeatures>> =
Arc::new(DashMap::default());
let upstream_engine_cache: Arc<DashMap<String, EngineState>> = Arc::new(DashMap::default());
let upstream_token_cache: Arc<DashMap<String, EdgeToken>> = Arc::new(token_cache);
let example_features = features_from_disk("../examples/features.json");
let cache_key = cache_key(&token);
let mut engine_state = EngineState::default();
engine_state.take_state(example_features.clone());
upstream_features_cache.insert(cache_key.clone(), example_features.clone());
upstream_engine_cache.insert(cache_key.clone(), engine_state);
let mut server = client_api_test_server(
upstream_token_cache,
upstream_features_cache,
upstream_engine_cache,
)
.await;
let unleash_client = UnleashClient::new(server.url("/").as_str(), None).unwrap();
let features_cache: Arc<DashMap<String, ClientFeatures>> = Arc::new(DashMap::default());
let engine_cache: Arc<DashMap<String, EngineState>> = Arc::new(DashMap::default());
let feature_refresher = FeatureRefresher::new(
Arc::new(unleash_client),
features_cache,
engine_cache,
Duration::milliseconds(1),
None,
);
feature_refresher
.register_token_for_refresh(token, None)
.await;
assert!(!feature_refresher.tokens_to_refresh.is_empty());
feature_refresher.refresh_features().await;
assert!(!feature_refresher.tokens_to_refresh.is_empty());
assert!(!feature_refresher.features_cache.is_empty());
assert!(!feature_refresher.engine_cache.is_empty());
server.stop().await;
tokio::time::sleep(std::time::Duration::from_millis(5)).await; // To ensure our refresh is due
feature_refresher.refresh_features().await;
assert!(feature_refresher.tokens_to_refresh.is_empty());
assert!(!feature_refresher.features_cache.is_empty());
assert!(!feature_refresher.engine_cache.is_empty());
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The crux is here. Previously, when we receive 404 or connection failed we'd remove the features_cache and the engine_cache as well, thus removing all the durability built into Edge for when upstream goes away.

}

#[tokio::test]
pub async fn when_we_have_a_cache_and_token_gets_removed_caches_are_emptied() {
let upstream_features_cache: Arc<DashMap<String, ClientFeatures>> =
Expand Down