1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187

#![deny(clippy::all, clippy::cargo)]
#![warn(missing_docs, nonstandard_style, rust_2018_idioms)]
#![warn(clippy::multiple_crate_versions)]

//! This crate includes a base HTTP client to interact with
//! the AWS Lambda Runtime API.
use http::{uri::PathAndQuery, uri::Scheme, Request, Response, Uri};
use hyper::{
    client::{connect::Connection, HttpConnector},
    Body,
};
use std::{convert::TryInto, fmt::Debug};
use tokio::io::{AsyncRead, AsyncWrite};
use tower_service::Service;

const USER_AGENT_HEADER: &str = "User-Agent";
const DEFAULT_USER_AGENT: &str = concat!("aws-lambda-rust/", env!("CARGO_PKG_VERSION"));
const CUSTOM_USER_AGENT: Option<&str> = option_env!("LAMBDA_RUNTIME_USER_AGENT");

/// Error type that lambdas may result in
pub type Error = Box<dyn std::error::Error + Send + Sync + 'static>;

/// API client to interact with the AWS Lambda Runtime API.
#[derive(Debug)]
pub struct Client<C = HttpConnector> {
    /// The runtime API URI
    pub base: Uri,
    /// The client that manages the API connections
    pub client: hyper::Client<C>,
}

impl Client {
    /// Create a builder struct to configure the client.
    pub fn builder() -> ClientBuilder<HttpConnector> {
        ClientBuilder {
            connector: HttpConnector::new(),
            uri: None,
        }
    }
}

impl<C> Client<C>
where
    C: hyper::client::connect::Connect + Sync + Send + Clone + 'static,
{
    /// Send a given request to the Runtime API.
    /// Use the client's base URI to ensure the API endpoint is correct.
    pub async fn call(&self, req: Request<Body>) -> Result<Response<Body>, Error> {
        let req = self.set_origin(req)?;
        let response = self.client.request(req).await?;
        Ok(response)
    }

    /// Create a new client with a given base URI and HTTP connector.
    pub fn with(base: Uri, connector: C) -> Self {
        let client = hyper::Client::builder().build(connector);
        Self { base, client }
    }

    fn set_origin<B>(&self, req: Request<B>) -> Result<Request<B>, Error> {
        let (mut parts, body) = req.into_parts();
        let (scheme, authority, base_path) = {
            let scheme = self.base.scheme().unwrap_or(&Scheme::HTTP);
            let authority = self.base.authority().expect("Authority not found");
            let base_path = self.base.path().trim_end_matches('/');
            (scheme, authority, base_path)
        };
        let path = parts.uri.path_and_query().expect("PathAndQuery not found");
        let pq: PathAndQuery = format!("{}{}", base_path, path).parse().expect("PathAndQuery invalid");

        let uri = Uri::builder()
            .scheme(scheme.as_ref())
            .authority(authority.as_ref())
            .path_and_query(pq)
            .build()
            .map_err(Box::new)?;

        parts.uri = uri;
        Ok(Request::from_parts(parts, body))
    }
}

/// Builder implementation to construct any Runtime API clients.
pub struct ClientBuilder<C: Service<http::Uri> = hyper::client::HttpConnector> {
    connector: C,
    uri: Option<http::Uri>,
}

impl<C> ClientBuilder<C>
where
    C: Service<http::Uri> + Clone + Send + Sync + Unpin + 'static,
    <C as Service<http::Uri>>::Future: Unpin + Send,
    <C as Service<http::Uri>>::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
    <C as Service<http::Uri>>::Response: AsyncRead + AsyncWrite + Connection + Unpin + Send + 'static,
{
    /// Create a new builder with a given HTTP connector.
    pub fn with_connector<C2>(self, connector: C2) -> ClientBuilder<C2>
    where
        C2: Service<http::Uri> + Clone + Send + Sync + Unpin + 'static,
        <C2 as Service<http::Uri>>::Future: Unpin + Send,
        <C2 as Service<http::Uri>>::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
        <C2 as Service<http::Uri>>::Response: AsyncRead + AsyncWrite + Connection + Unpin + Send + 'static,
    {
        ClientBuilder {
            connector,
            uri: self.uri,
        }
    }

    /// Create a new builder with a given base URI.
    /// Inherits all other attributes from the existent builder.
    pub fn with_endpoint(self, uri: http::Uri) -> Self {
        Self { uri: Some(uri), ..self }
    }

    /// Create the new client to interact with the Runtime API.
    pub fn build(self) -> Result<Client<C>, Error> {
        let uri = match self.uri {
            Some(uri) => uri,
            None => {
                let uri = std::env::var("AWS_LAMBDA_RUNTIME_API").expect("Missing AWS_LAMBDA_RUNTIME_API env var");
                uri.try_into().expect("Unable to convert to URL")
            }
        };
        Ok(Client::with(uri, self.connector))
    }
}

/// Create a request builder.
/// This builder uses `aws-lambda-rust/CRATE_VERSION` as
/// the default User-Agent.
/// Configure environment variable `LAMBDA_RUNTIME_USER_AGENT`
/// at compile time to modify User-Agent value.
pub fn build_request() -> http::request::Builder {
    const USER_AGENT: &str = match CUSTOM_USER_AGENT {
        Some(value) => value,
        None => DEFAULT_USER_AGENT,
    };
    http::Request::builder().header(USER_AGENT_HEADER, USER_AGENT)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_set_origin() {
        let base = "http://localhost:9001";
        let client = Client::builder().with_endpoint(base.parse().unwrap()).build().unwrap();
        let req = build_request()
            .uri("/2018-06-01/runtime/invocation/next")
            .body(())
            .unwrap();
        let req = client.set_origin(req).unwrap();
        assert_eq!(
            "http://localhost:9001/2018-06-01/runtime/invocation/next",
            &req.uri().to_string()
        );
    }

    #[test]
    fn test_set_origin_with_base_path() {
        let base = "http://localhost:9001/foo";
        let client = Client::builder().with_endpoint(base.parse().unwrap()).build().unwrap();
        let req = build_request()
            .uri("/2018-06-01/runtime/invocation/next")
            .body(())
            .unwrap();
        let req = client.set_origin(req).unwrap();
        assert_eq!(
            "http://localhost:9001/foo/2018-06-01/runtime/invocation/next",
            &req.uri().to_string()
        );

        let base = "http://localhost:9001/foo/";
        let client = Client::builder().with_endpoint(base.parse().unwrap()).build().unwrap();
        let req = build_request()
            .uri("/2018-06-01/runtime/invocation/next")
            .body(())
            .unwrap();
        let req = client.set_origin(req).unwrap();
        assert_eq!(
            "http://localhost:9001/foo/2018-06-01/runtime/invocation/next",
            &req.uri().to_string()
        );
    }
}