feat: Add CredentialProvider & support v1 tokens (#146)

Add the `CredentialProvider` construct that we have in other SDKs to parse auth tokens and get cache and control endpoints. This replaces the `EndpointResolver` and `jwt` modules.

Credential Providers can either be created from a string or an environment variable. They can optionally override the cache and control endpoints (or just one or the other).

```rust
    let credential_provider =
        CredentialProviderBuilder::new_from_environment_variable("TEST_AUTH_TOKEN")
            .build()
            .expect("TEST_AUTH_TOKEN must be set");

```

```rust
    let credential_provider =
        CredentialProviderBuilder::new_from_string("my_test_token")
            .with_cache_endpoint("cache.localhost")
            .with_control_endpoint("control.localhost")
            .build()
            .expect("could not parse token and endpoints")
```
then
```rust
 let mut momento = SimpleCacheClientBuilder::new(credential_provider, Duration::from_secs(30))?.build();
```

Co-authored-by: Kenny <[email protected]>

README.md

@@ -14,20 +14,11 @@ Rust SDK for Momento, a serverless cache that automatically scales without any o
 
 <br/>
 
-## Preview Features
-
-This SDK contains APIs for interacting with collection data structures: Lists, Sets, and Dictionaries.  These APIs
-are currently in preview.  If you would like to request early access to the data structure APIs, please contact us
-at `[email protected]`.
-
-**Note that if you call the List, Set, or Dictionary APIs without first signing up for our early access preview, you
-the calls will result in an `Unsupported operation` error.**
-
 ## Getting Started 🏃
 
 ### Requirements
 
-- A Momento Auth Token is required, you can generate one using the [Momento CLI](https://github.com/momentohq/momento-cli)
+- A Momento Auth Token is required, you can generate one using the [Momento Console](https://console.gomomento.com)
 
 <br/>
 
@@ -40,17 +31,19 @@ Check out [example](./example/) directory!
 ### Using Momento
 
 ```rust
-use momento::simple_cache_client::SimpleCacheClientBuilder;
+use momento::{CredentialProviderBuilder, SimpleCacheClientBuilder};
 use std::env;
 use std::num::NonZeroU64;
 
 async fn demo_cache_usage() {
     // Initialize Momento
-    let auth_token = env::var("MOMENTO_AUTH_TOKEN")
-        .expect("env var MOMENTO_AUTH_TOKEN must be set to your auth token");
+    let credential_provider =
+        CredentialProviderBuilder::new_from_environment_variable("MOMENTO_AUTH_TOKEN")
+            .build()
+            .expect("env var MOMENTO_AUTH_TOKEN must be set to your auth token");
     let item_default_ttl_seconds = 60;
     let mut cache_client = SimpleCacheClientBuilder::new(
-        auth_token,
+        credential_provider,
         NonZeroU64::new(item_default_ttl_seconds).unwrap(),
     )
     .unwrap()

src/auth.rs

@@ -5,7 +5,6 @@ use thiserror::Error;
 use tonic::{codegen::http::uri::InvalidUri, transport::Channel, Streaming};
 
 use crate::{
-    endpoint_resolver::MomentoEndpointsResolver,
     response::MomentoError,
     utils::{connect_channel_lazily, ChannelConnectError},
 };
@@ -190,7 +189,16 @@ async fn consume_login_messages(
 }
 
 fn auth_client() -> Result<AuthClient<Channel>, AuthError> {
-    let hostname = MomentoEndpointsResolver::get_login_endpoint();
+    let hostname = get_login_endpoint();
     let channel = connect_channel_lazily(&hostname)?;
     Ok(AuthClient::new(channel))
 }
+
+fn get_login_endpoint() -> String {
+    const LOGIN_HOSTNAMES: &[&str] = &["control.cell-us-east-1-1.prod.a.momentohq.com"];
+    std::env::var("LOGIN_ENDPOINT").unwrap_or_else(|_| {
+        let random = rand::random::<usize>();
+        let hostname = LOGIN_HOSTNAMES[random % LOGIN_HOSTNAMES.len()].to_string();
+        format!("https://{hostname}:443")
+    })
+}