feat(http): Implement Isahc HTTP checker (#282)

Adds a new Isahc HTTP checker.

We would like to experiment with this checker to collect better metrics
about the HTTP requets being made.

There are a few things we still need to fix before we can enable this

- [ ] We need some way to restrict (See internal
https://getsentry.atlassian.net/jira/servicedesk/projects/INF/issues/INF-449)
- [ ] We need to be able to configure the DNS servers since our kube-dns
      is flakey. See sagebind/isahc#364

Author: evanpurkhiser

Cargo.lock

@@ -47,6 +47,8 @@ time = "0.3"
 ctor = "0.2"
 hostname = "0.4.0"
 tokio-metrics = "0.4.0"
+isahc = "1.7.2"
+http = "1.2.0"
 [patch.crates-io]
 rdkafka = { git = "https://github.com/fede1024/rust-rdkafka" }
 reqwest = { git = "https://github.com/getsentry/reqwest-uptime", rev = "be34e1e20c88190dfd46dd609f43aeb15e9ede1b" }

Cargo.toml

@@ -25,6 +25,13 @@ pub enum ProducerMode {
     Vector,
 }
 
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Deserialize, Serialize)]
+#[serde(rename_all = "snake_case")]
+pub enum CheckerMode {
+    Reqwest,
+    Isahc,
+}
+
 #[serde_as]
 #[derive(PartialEq, Debug, Serialize, Deserialize)]
 pub struct MetricsConfig {
@@ -78,6 +85,9 @@ pub struct Config {
     /// Which config provider to use to load configs into memory
     pub config_provider_mode: ConfigProviderMode,
 
+    /// Which checker implementation to use to run the HTTP checks.
+    pub checker_mode: CheckerMode,
+
     /// which producer to use to send results
     pub producer_mode: ProducerMode,
 
@@ -151,6 +161,7 @@ impl Default for Config {
             results_kafka_cluster: vec![],
             results_kafka_topic: "uptime-results".to_owned(),
             config_provider_mode: ConfigProviderMode::Redis,
+            checker_mode: CheckerMode::Reqwest,
             vector_batch_size: 10,
             vector_endpoint: "http://localhost:8020".to_owned(),
             producer_mode: ProducerMode::Kafka,
@@ -222,12 +233,9 @@ mod tests {
     use std::net::IpAddr;
     use std::{borrow::Cow, collections::BTreeMap, path::PathBuf};
 
-    use crate::{
-        app::{cli, config::ProducerMode},
-        logging,
-    };
+    use crate::{app::cli, logging};
 
-    use super::{Config, ConfigProviderMode, MetricsConfig};
+    use super::{CheckerMode, Config, ConfigProviderMode, MetricsConfig, ProducerMode};
 
     fn test_with_config<F>(yaml: &str, env_vars: &[(&str, &str)], test_fn: F)
     where
@@ -292,6 +300,7 @@ mod tests {
                         ],
                         results_kafka_topic: "uptime-results".to_owned(),
                         config_provider_mode: ConfigProviderMode::Redis,
+                        checker_mode: CheckerMode::Reqwest,
                         config_provider_redis_update_ms: 1000,
                         config_provider_redis_total_partitions: 128,
                         redis_enable_cluster: false,
@@ -377,6 +386,7 @@ mod tests {
                         ],
                         results_kafka_topic: "uptime-results".to_owned(),
                         config_provider_mode: ConfigProviderMode::Redis,
+                        checker_mode: CheckerMode::Reqwest,
                         config_provider_redis_update_ms: 2000,
                         config_provider_redis_total_partitions: 32,
                         redis_enable_cluster: true,

src/app/config.rs

@@ -1,9 +1,12 @@
 pub mod dummy_checker;
-pub mod http_checker;
 pub mod ip_filter;
+pub mod isahc_checker;
+pub mod reqwest_checker;
 
 use std::future::Future;
 
+use isahc_checker::IsahcChecker;
+use reqwest_checker::ReqwestChecker;
 use sentry::protocol::SpanId;
 use uuid::Uuid;
 
@@ -50,3 +53,30 @@ pub trait Checker: Send + Sync {
         region: &str,
     ) -> impl Future<Output = CheckResult> + Send;
 }
+
+#[derive(Debug)]
+pub enum HttpChecker {
+    ReqwestChecker(ReqwestChecker),
+    IsahcChecker(IsahcChecker),
+}
+
+impl Checker for HttpChecker {
+    async fn check_url(&self, config: &CheckConfig, tick: &Tick, region: &str) -> CheckResult {
+        match self {
+            Self::IsahcChecker(c) => c.check_url(config, tick, region).await,
+            Self::ReqwestChecker(c) => c.check_url(config, tick, region).await,
+        }
+    }
+}
+
+impl From<ReqwestChecker> for HttpChecker {
+    fn from(checker: ReqwestChecker) -> Self {
+        HttpChecker::ReqwestChecker(checker)
+    }
+}
+
+impl From<IsahcChecker> for HttpChecker {
+    fn from(checker: IsahcChecker) -> Self {
+        HttpChecker::IsahcChecker(checker)
+    }
+}