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

/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */

//! Load timeout configuration properties from environment variables

use crate::parsing::parse_str_as_timeout;

use aws_smithy_types::timeout;
use aws_smithy_types::tristate::TriState;
use aws_types::os_shim_internal::Env;

use std::time::Duration;

// Currently unsupported timeouts
const ENV_VAR_CONNECT_TIMEOUT: &str = "AWS_CONNECT_TIMEOUT";
const ENV_VAR_TLS_NEGOTIATION_TIMEOUT: &str = "AWS_TLS_NEGOTIATION_TIMEOUT";
const ENV_VAR_READ_TIMEOUT: &str = "AWS_READ_TIMEOUT";

// Supported timeouts
const ENV_VAR_API_CALL_ATTEMPT_TIMEOUT: &str = "AWS_API_CALL_ATTEMPT_TIMEOUT";
const ENV_VAR_API_CALL_TIMEOUT: &str = "AWS_API_CALL_TIMEOUT";

/// Load a timeout_config from environment variables
///
/// This provider will check the values of the following variables in order to build a
/// [`timeout::Config`](aws_smithy_types::timeout::Config)
///
/// - `AWS_API_CALL_ATTEMPT_TIMEOUT`
/// - `AWS_API_CALL_TIMEOUT`
///
/// Timeout values represent the number of seconds before timing out and must be non-negative floats
/// or integers. NaN and infinity are also invalid.
#[derive(Debug, Default)]
pub struct EnvironmentVariableTimeoutConfigProvider {
    env: Env,
}

impl EnvironmentVariableTimeoutConfigProvider {
    /// Create a new [`EnvironmentVariableTimeoutConfigProvider`]
    pub fn new() -> Self {
        EnvironmentVariableTimeoutConfigProvider { env: Env::real() }
    }

    #[doc(hidden)]
    /// Create a timeout config provider from a given [`Env`]
    ///
    /// This method is used for tests that need to override environment variables.
    pub fn new_with_env(env: Env) -> Self {
        EnvironmentVariableTimeoutConfigProvider { env }
    }

    /// Attempt to create a new [`timeout::Config`](aws_smithy_types::timeout::Config) from environment variables
    pub fn timeout_config(&self) -> Result<timeout::Config, timeout::ConfigError> {
        // Warn users that set unsupported timeouts in their profile
        for timeout in [
            ENV_VAR_CONNECT_TIMEOUT,
            ENV_VAR_TLS_NEGOTIATION_TIMEOUT,
            ENV_VAR_READ_TIMEOUT,
        ] {
            warn_if_unsupported_timeout_is_set(&self.env, timeout);
        }

        let api_call_attempt_timeout =
            construct_timeout_from_env_var(&self.env, ENV_VAR_API_CALL_ATTEMPT_TIMEOUT)?;
        let api_call_timeout = construct_timeout_from_env_var(&self.env, ENV_VAR_API_CALL_TIMEOUT)?;

        let api_timeouts = timeout::Api::new()
            .with_call_timeout(api_call_timeout)
            .with_call_attempt_timeout(api_call_attempt_timeout);

        // Only API-related timeouts are currently supported
        Ok(timeout::Config::new().with_api_timeouts(api_timeouts))
    }
}

fn construct_timeout_from_env_var(
    env: &Env,
    var: &'static str,
) -> Result<TriState<Duration>, timeout::ConfigError> {
    match env.get(var).ok() {
        Some(timeout) => parse_str_as_timeout(&timeout, var.into(), "environment variable".into())
            .map(TriState::Set),
        None => Ok(TriState::Unset),
    }
}

fn warn_if_unsupported_timeout_is_set(env: &Env, var: &'static str) {
    if env.get(var).is_ok() {
        tracing::warn!(
                "Environment variable for '{}' timeout was set but that feature is currently unimplemented so the setting will be ignored. \
                To help us prioritize support for this feature, please upvote aws-sdk-rust#151 (https://github.com/awslabs/aws-sdk-rust/issues/151)",
            var
        )
    }
}

#[cfg(test)]
mod test {
    use super::{
        EnvironmentVariableTimeoutConfigProvider, ENV_VAR_API_CALL_ATTEMPT_TIMEOUT,
        ENV_VAR_API_CALL_TIMEOUT,
    };
    use aws_smithy_types::timeout;
    use aws_smithy_types::tristate::TriState;
    use aws_types::os_shim_internal::Env;
    use std::time::Duration;

    fn test_provider(vars: &[(&str, &str)]) -> EnvironmentVariableTimeoutConfigProvider {
        EnvironmentVariableTimeoutConfigProvider::new_with_env(Env::from_slice(vars))
    }

    #[test]
    fn no_defaults() {
        let built = test_provider(&[]).timeout_config().unwrap();

        assert_eq!(built.api.call_timeout(), TriState::Unset);
        assert_eq!(built.api.call_attempt_timeout(), TriState::Unset);
    }

    #[test]
    fn all_fields_can_be_set_at_once() {
        let expected_api_timeouts = timeout::Api::new()
            .with_call_attempt_timeout(TriState::Set(Duration::from_secs_f32(4.0)))
            // Some floats can't be represented as f32 so this duration will end up equalling the
            // duration from the env.
            .with_call_timeout(TriState::Set(Duration::from_secs_f32(900012350.0)));
        let expected_timeouts = timeout::Config::new().with_api_timeouts(expected_api_timeouts);

        assert_eq!(
            test_provider(&[
                (ENV_VAR_API_CALL_ATTEMPT_TIMEOUT, "04.000"),
                (ENV_VAR_API_CALL_TIMEOUT, "900012345.0")
            ])
            .timeout_config()
            .unwrap(),
            expected_timeouts
        );
    }
}