feat: introduce properties-config cargo feature

testcontainers/Cargo.toml

@@ -25,7 +25,7 @@ futures = "0.3"
 log = "0.4"
 parse-display = "0.9.0"
 serde = { version = "1", features = ["derive"] }
-serde-java-properties = "0.1.1"
+serde-java-properties = { version = "0.1.1", optional = true }
 serde_json = "1"
 serde_with = "3.7.0"
 signal-hook = { version = "0.3", optional = true }
@@ -37,6 +37,7 @@ url = { version = "2", features = ["serde"] }
 default = []
 blocking = []
 watchdog = ["signal-hook", "conquer-once"]
+properties-config = ["serde-java-properties"]
 
 [dev-dependencies]
 pretty_env_logger = "0.5"

testcontainers/src/core/env/config.rs

@@ -3,12 +3,11 @@ use std::{
     str::FromStr,
 };
 
-use serde::Deserialize;
-use serde_with::serde_as;
 use url::Url;
 
 use crate::core::env::GetEnvValue;
 
+#[cfg(feature = "properties-config")]
 const TESTCONTAINERS_PROPERTIES: &str = ".testcontainers.properties";
 
 /// The default `DOCKER_HOST` address that we will try to connect to.
@@ -28,8 +27,9 @@ pub(crate) struct Config {
     command: Option<Command>,
 }
 
-#[serde_as]
-#[derive(Debug, Default, Deserialize)]
+#[cfg(feature = "properties-config")]
+#[serde_with::serde_as]
+#[derive(Debug, Default, serde::Deserialize)]
 struct TestcontainersProperties {
     #[serde(rename = "tc.host")]
     tc_host: Option<Url>,
@@ -42,6 +42,7 @@ struct TestcontainersProperties {
     cert_path: Option<PathBuf>,
 }
 
+#[cfg(feature = "properties-config")]
 impl TestcontainersProperties {
     async fn load() -> Option<Self> {
         let home_dir = dirs::home_dir()?;
@@ -61,16 +62,22 @@ impl Config {
         E: GetEnvValue,
     {
         let env_config = Self::load_from_env_config::<E>();
-        let properties = TestcontainersProperties::load().await.unwrap_or_default();
-
-        // Environment variables take precedence over properties
-        Self {
-            tc_host: env_config.tc_host.or(properties.tc_host),
-            host: env_config.host.or(properties.host),
-            tls_verify: env_config.tls_verify.or(properties.tls_verify),
-            cert_path: env_config.cert_path.or(properties.cert_path),
-            command: env_config.command,
+
+        #[cfg(feature = "properties-config")]
+        {
+            let properties = TestcontainersProperties::load().await.unwrap_or_default();
+
+            // Environment variables take precedence over properties
+            Self {
+                tc_host: env_config.tc_host.or(properties.tc_host),
+                host: env_config.host.or(properties.host),
+                tls_verify: env_config.tls_verify.or(properties.tls_verify),
+                cert_path: env_config.cert_path.or(properties.cert_path),
+                command: env_config.command,
+            }
         }
+        #[cfg(not(feature = "properties-config"))]
+        env_config
     }
 
     fn load_from_env_config<E>() -> Self
@@ -142,3 +149,34 @@ impl FromStr for Command {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[cfg(feature = "properties-config")]
+    #[test]
+    fn deserialize_java_properties() {
+        let tc_host = Url::parse("http://tc-host").unwrap();
+        let docker_host = Url::parse("http://docker-host").unwrap();
+        let tls_verify = 1;
+        let cert_path = "/path/to/cert";
+
+        let file_content = format!(
+            r"
+            tc.host={tc_host}
+            docker.host={docker_host}
+            docker.tls.verify={tls_verify}
+            docker.cert.path={cert_path}
+        "
+        );
+        let properties: TestcontainersProperties =
+            serde_java_properties::from_slice(file_content.as_bytes())
+                .expect("Failed to parse properties");
+
+        assert_eq!(properties.tc_host, Some(tc_host));
+        assert_eq!(properties.host, Some(docker_host));
+        assert_eq!(properties.tls_verify, Some(tls_verify == 1));
+        assert_eq!(properties.cert_path, Some(PathBuf::from(cert_path)));
+    }
+}

testcontainers/src/lib.rs

@@ -28,6 +28,19 @@
 //!
 //! See examples in the corresponding runner ([`AsyncRunner`] and [`SyncRunner`])
 //!
+//! ### Docker host resolution
+//!
+//! You can change the configuration of the Docker host used by the client in two ways:
+//! - environment variables
+//! - `~/.testcontainers.properties` file (a Java properties file, enabled by the `properties-config` feature)
+//!
+//! ##### The host is resolved in the following order:
+//!
+//! 1. Docker host from the `tc.host` property in the `~/.testcontainers.properties` file.
+//! 2. `DOCKER_HOST` environment variable.
+//! 3. Docker host from the "docker.host" property in the `~/.testcontainers.properties` file.
+//! 4. Else, the default Docker socket will be returned.
+//!
 //! # Ecosystem
 //!
 //! `testcontainers` is the core crate that provides an API for working with containers in a test environment.