如果未找到环境变量,我如何回退以使用已解析文件(config.yml
)中的凭据?为了进行测试,我使用的是this example:
extern crate rusoto_core;
extern crate rusoto_s3;
use rusoto_core::credential::ChainProvider;
use rusoto_core::request::HttpClient;
use rusoto_core::Region;
use rusoto_s3::{S3, S3Client};
use std::time::{Duration, Instant};
fn main() {
let mut chain = ChainProvider::new();
chain.set_timeout(Duration::from_millis(200));
let s3client = S3Client::new_with(
HttpClient::new().expect("failed to create request dispatcher"),
chain,
Region::UsEast1,
);
let start = Instant::now();
println!("Starting up at {:?}", start);
match s3client.list_buckets().sync() {
Err(e) => println!("Error listing buckets: {}", e),
Ok(buckets) => println!("Buckets found: {:?}", buckets),
};
println!("Took {:?}", Instant::now().duration_since(start));
}
它可以工作,但是需要环境变量AWS_ACCESS_KEY_ID
和AWS_SECRET_ACCESS_KEY
。我想对其进行扩展,以便在没有定义的环境变量的情况下,可以使用在已解析文件中找到的键:
// parse config file
let file = std::fs::File::open("config.yml").expect("Unable to open file");
let yml: Config = match serde_yaml::from_reader(file) {
Err(err) => {
println!("Error: {}", err);
return;
}
Ok(yml) => yml,
};
例如config.yml
可能类似于:
---
endpoint: s3.provider
access_key: ACCESS_KEY_ID
secret_key: SECRET_ACCESS_KEY
我可以添加到chain
以使用在config.yml
中找到的凭据,可能类似于:
let config_provider = StaticProvider::new_minimal(yml.access_key, yml.secret_key);
如何优先考虑环境,如果找不到,则使用StaticProvider
提供的凭据?
ChainProvider
实际上具有four sources来检查AWS凭证。第三个是位于用户主目录中的AWS配置文件。但其格式是预定的。
如果您坚持使用自己的YAML文件,则可以像这样将EnvironmentProvider
和StaticProvider
链接在一起:
use futures::future::Future;
use rusoto_core::request::HttpClient;
use rusoto_core::Region;
use rusoto_credential::{
AwsCredentials,
CredentialsError,
EnvironmentProvider,
ProvideAwsCredentials,
StaticProvider,
};
use rusoto_s3::{S3, S3Client};
use std::time::Instant;
struct MyChainProvider {
access_key: String,
secret_key: String,
}
impl ProvideAwsCredentials for MyChainProvider {
type Future = Box<dyn Future<Item=AwsCredentials, Error=CredentialsError> + Send>;
fn credentials(&self) -> Self::Future {
let access_key = self.access_key.clone();
let secret_key = self.secret_key.clone();
let future = EnvironmentProvider::default().credentials()
.or_else(move |_| -> Self::Future {
Box::new(StaticProvider::new_minimal(access_key, secret_key).credentials())
});
Box::new(future)
}
}
fn main() {
let chain = MyChainProvider {
access_key: ...,
secret_key: ...,
};
let s3client = S3Client::new_with(
HttpClient::new().expect("failed to create request dispatcher"),
chain,
Region::UsEast1,
);
...
}