Add an environment variable for UV_VENV_RELOCATABLE (#18331)

Closes https://github.com/astral-sh/uv/issues/18319.

crates/uv-cli/src/lib.rs

@@ -3166,7 +3166,7 @@ pub struct VenvArgs {
     #[arg(long)]
     pub system_site_packages: bool,
 
-    /// Make the virtual environment relocatable.
+    /// Make the virtual environment relocatable [env: UV_VENV_RELOCATABLE=]
     ///
     /// A relocatable virtual environment can be moved around and redistributed without invalidating
     /// its associated entrypoint and activation scripts.
@@ -3179,6 +3179,7 @@ pub struct VenvArgs {
     /// absolute paths), the entrypoints and scripts themselves will _not_ be relocatable. In other
     /// words, copying those entrypoints and scripts to a location outside the environment will not
     /// work, as they reference paths relative to the environment itself.
+    #[expect(clippy::doc_markdown)]
     #[arg(long, overrides_with("no_relocatable"))]
     pub relocatable: bool,
 

crates/uv-settings/src/lib.rs

@@ -663,6 +663,7 @@ pub struct EnvironmentOptions {
     pub no_env_file: EnvFlag,
     pub venv_seed: EnvFlag,
     pub venv_clear: EnvFlag,
+    pub venv_relocatable: EnvFlag,
     pub init_bare: EnvFlag,
 }
 
@@ -756,6 +757,7 @@ impl EnvironmentOptions {
             no_env_file: EnvFlag::new(EnvVars::UV_NO_ENV_FILE)?,
             venv_seed: EnvFlag::new(EnvVars::UV_VENV_SEED)?,
             venv_clear: EnvFlag::new(EnvVars::UV_VENV_CLEAR)?,
+            venv_relocatable: EnvFlag::new(EnvVars::UV_VENV_RELOCATABLE)?,
             init_bare: EnvFlag::new(EnvVars::UV_INIT_BARE)?,
         })
     }

crates/uv-static/src/env_vars.rs

@@ -477,6 +477,11 @@ impl EnvVars {
     #[attr_added_in("0.8.0")]
     pub const UV_VENV_CLEAR: &'static str = "UV_VENV_CLEAR";
 
+    /// Equivalent to the `--relocatable` command-line argument. If set, the virtual
+    /// environment will be relocatable.
+    #[attr_added_in("0.10.8")]
+    pub const UV_VENV_RELOCATABLE: &'static str = "UV_VENV_RELOCATABLE";
+
     /// Install seed packages (one or more of: `pip`, `setuptools`, and `wheel`) into the virtual environment
     /// created by `uv venv`.
     ///

crates/uv/src/settings.rs

@@ -3489,6 +3489,7 @@ impl VenvSettings {
         // Resolve flags from CLI and environment variables.
         let seed = seed || environment.venv_seed.value == Some(true);
         let clear = clear || environment.venv_clear.value == Some(true);
+        let relocatable = relocatable || environment.venv_relocatable.value == Some(true);
 
         Self {
             seed,

crates/uv/tests/it/venv.rs

@@ -1307,6 +1307,29 @@ fn verify_pyvenv_cfg_relocatable() {
     activate_csh.assert(predicates::path::missing());
 }
 
+/// With `UV_VENV_RELOCATABLE=1`, the virtual environment is relocatable.
+#[test]
+fn verify_pyvenv_cfg_relocatable_env_var() {
+    let context = uv_test::test_context!("3.12");
+
+    // Create a virtual environment at `.venv` with the env var.
+    context
+        .venv()
+        .arg(context.venv.as_os_str())
+        .arg("--clear")
+        .arg("--python")
+        .arg("3.12")
+        .env("UV_VENV_RELOCATABLE", "1")
+        .assert()
+        .success();
+
+    let pyvenv_cfg = context.venv.child("pyvenv.cfg");
+    pyvenv_cfg.assert(predicates::path::is_file());
+
+    // Relocatable flag is set.
+    pyvenv_cfg.assert(predicates::str::contains("relocatable = true"));
+}
+
 /// With `relocatable-envs-default` preview feature, venvs are relocatable by default.
 #[test]
 fn relocatable_envs_default_preview() {