Crate remote_config

Remote config

This crate provides easy way to asynchronously pull configuration files from external source (e.g. centralized HTTP service).

It was originally developed to load public keys from https://www.googleapis.com/robot/v1/metadata/x509/securetoken@system.gserviceaccount.com and revalidate them periodically.

Features

• Supports both static and wrapped in Arc configs.
• Flexible RemoteConfig struct that uses any custom data provider and automatically revalidates data when it becomes stale.
• Supports loading configuration in JSON, YAML, XML and TOML via HTTP out of the box (Uses Cache-Control and Content-Type headers).

Documentation and examples

Refer to documentation and examples on docs rs.

State of the project

Project is not guaranteed to actively receive any new features without requests, but is maintained. Feature requests, bug reports, pull requests, corrections to docs or examples are gladly accepted.

Code is tested, with unit and integration tests.

Currently, this project is not used in production environment.

Contributing

If you found a bug, submit an issue or pull requests.

Any contribution intentionally submitted for inclusion in Tokio by you, shall be licensed as MIT, without any additional terms or conditions.

Licence

This project is licenced under the MIT licence.

Feature flags

Main crate features

This features affect whole crate or RemoteConfig implementation directly

• tracing - enables tracing with tokio
• non_static - enables implementation of RemoteConfig that uses &Arc<RemoteConfig> instead of &'static RemoteConfig. As the intended use case for this crate is to store RemoteConfig in static tokio’s OnceCell, this feature is not enabled by default.

Data providers

All built-in data providers and their features can be enabled or disabled using this feature flags.

• http - enables HttpDataProvider that uses reqwest client to load data from remote source (enabled by default)
  • serde - enables convenient data extractor for http data provider, that automatically parses necessary headers and deserializes data based on content-type (enabled by default)
    • json - json deserialization support (enabled by default). Deserializer: serde_json
    • yaml - yaml deserialization support. Deserializer: serde_yaml
    • toml - toml deserialization support. Deserializer: toml
    • xml - xml deserialization support. Deserializer: serde-xml-rs

Examples

use std::collections::HashMap;
use std::time::{Duration, SystemTime};
use arc_swap::access::Access;
use reqwest::{Client, Url};
use reqwest::header::{ACCEPT, AUTHORIZATION, HeaderMap, HeaderValue};
use serde::de::Unexpected::Str;
use tokio::sync::OnceCell;
use std::string::String;
use remote_config::config::RemoteConfig;
use remote_config::data_providers::http::HttpDataProvider;
use remote_config::data_providers::http::serde_extractor::SerdeDataExtractor;

type Data = HashMap<String, String>;
async fn init_config() -> RemoteConfig<Data, HttpDataProvider<Data, SerdeDataExtractor<Data>>> {
    // Configure http client
    let mut headers = HeaderMap::with_capacity(1);
    headers.insert(AUTHORIZATION, HeaderValue::from_str("Bearer: very_secret_token").unwrap());
    headers.insert(ACCEPT, HeaderValue::from_str("application/json").unwrap());
    let client = Client::builder().default_headers(headers).connect_timeout(Duration::from_secs(5)).build().unwrap();

    let data_provider = HttpDataProvider::new(client, Url::parse("https://example.com").unwrap(), SerdeDataExtractor::new());

    return RemoteConfig::new("Example named config".to_owned(), data_provider, Duration::from_secs(5)).await.unwrap();
}
// Note, that async OnceCell is used. You can use blocking OnceCell by changing init_config() to sync and using block_on() to wait for data load
static CONFIG: OnceCell<RemoteConfig<Data, HttpDataProvider<Data, SerdeDataExtractor<Data>>>> = OnceCell::const_new();
pub async fn do_some_things() {
    // You may want to handle errors properly instead of panicking
    let cfg = CONFIG.get_or_init(init_config).await.load().await.unwrap();

    let val = cfg.get("key").unwrap();
}

Modules

config

Remote Config instance and utility types See config::RemoteConfig struct.

data_providers

Data providers for RemoteConfig instance. Public traits are included to allow easy use of custom implementations.