Add UV_HTTP_RETRIES to customize retry counts (#14544)

I want to increase this number in CI and was surprised we didn't support
configuration yet.

crates/uv-client/src/base_client.rs

@@ -6,6 +6,7 @@ use std::sync::Arc;
 use std::time::Duration;
 use std::{env, io, iter};
 
+use anyhow::Context;
 use anyhow::anyhow;
 use http::{
     HeaderMap, HeaderName, HeaderValue, Method, StatusCode,
@@ -166,6 +167,25 @@ impl<'a> BaseClientBuilder<'a> {
         self
     }
 
+    /// Read the retry count from [`EnvVars::UV_HTTP_RETRIES`] if set, otherwise, make no change.
+    ///
+    /// Errors when [`EnvVars::UV_HTTP_RETRIES`] is not a valid u32.
+    pub fn retries_from_env(self) -> anyhow::Result<Self> {
+        // TODO(zanieb): We should probably parse this in another layer, but there's not a natural
+        // fit for it right now
+        if let Some(value) = env::var_os(EnvVars::UV_HTTP_RETRIES) {
+            Ok(self.retries(
+                value
+                    .to_string_lossy()
+                    .as_ref()
+                    .parse::<u32>()
+                    .context("Failed to parse `UV_HTTP_RETRIES`")?,
+            ))
+        } else {
+            Ok(self)
+        }
+    }
+
     #[must_use]
     pub fn native_tls(mut self, native_tls: bool) -> Self {
         self.native_tls = native_tls;
@@ -238,7 +258,11 @@ impl<'a> BaseClientBuilder<'a> {
 
     /// Create a [`RetryPolicy`] for the client.
     fn retry_policy(&self) -> ExponentialBackoff {
-        ExponentialBackoff::builder().build_with_max_retries(self.retries)
+        let mut builder = ExponentialBackoff::builder();
+        if env::var_os(EnvVars::UV_TEST_NO_HTTP_RETRY_DELAY).is_some() {
+            builder = builder.retry_bounds(Duration::from_millis(0), Duration::from_millis(0));
+        }
+        builder.build_with_max_retries(self.retries)
     }
 
     pub fn build(&self) -> BaseClient {

crates/uv-client/src/registry_client.rs

@@ -115,6 +115,11 @@ impl<'a> RegistryClientBuilder<'a> {
         self
     }
 
+    pub fn retries_from_env(mut self) -> anyhow::Result<Self> {
+        self.base_client_builder = self.base_client_builder.retries_from_env()?;
+        Ok(self)
+    }
+
     #[must_use]
     pub fn native_tls(mut self, native_tls: bool) -> Self {
         self.base_client_builder = self.base_client_builder.native_tls(native_tls);