feat: Add DENO_CACHED_ONLY env var as alternative to --cached-only

cli/file_fetcher.rs

@@ -375,13 +375,7 @@ impl FileFetcher {
     }
 
     if self.cache_setting == CacheSetting::Only {
-      return Err(custom_error(
-        "NotCached",
-        format!(
-          "Specifier not found in cache: \"{}\", --cached-only is specified.",
-          specifier
-        ),
-      ));
+      return Err(cached_only_error(specifier));
     }
 
     let (source, content_type) = get_source_from_data_url(specifier)?;
@@ -424,13 +418,7 @@ impl FileFetcher {
     }
 
     if self.cache_setting == CacheSetting::Only {
-      return Err(custom_error(
-        "NotCached",
-        format!(
-          "Specifier not found in cache: \"{}\", --cached-only is specified.",
-          specifier
-        ),
-      ));
+      return Err(cached_only_error(specifier));
     }
 
     let blob = {
@@ -510,14 +498,7 @@ impl FileFetcher {
     }
 
     if self.cache_setting == CacheSetting::Only {
-      return futures::future::err(custom_error(
-        "NotCached",
-        format!(
-          "Specifier not found in cache: \"{}\", --cached-only is specified.",
-          specifier
-        ),
-      ))
-      .boxed();
+      return futures::future::err(cached_only_error(specifier)).boxed();
     }
 
     log::log!(
@@ -669,6 +650,16 @@ impl FileFetcher {
   }
 }
 
+fn cached_only_error(specifier: &ModuleSpecifier) -> AnyError {
+  custom_error(
+        "NotCached",
+        format!(
+          "Specifier not found in cache: \"{}\", --cached-only or DENO_CACHED_ONLY is specified.",
+          specifier
+        ),
+      )
+}
+
 #[cfg(test)]
 mod tests {
   use super::*;
@@ -1518,7 +1509,9 @@ mod tests {
     assert!(result.is_err());
     let err = result.unwrap_err();
     assert_eq!(get_custom_error_class(&err), Some("NotCached"));
-    assert_eq!(err.to_string(), "Specifier not found in cache: \"http://localhost:4545/002_hello.ts\", --cached-only is specified.");
+    assert!(err.to_string().contains(
+      "Specifier not found in cache: \"http://localhost:4545/002_hello.ts\""
+    ));
 
     let result = file_fetcher_02
       .fetch(&specifier, &mut Permissions::allow_all())

cli/flags.rs

@@ -377,13 +377,14 @@ static ENV_VARIABLES_HELP: &str = r#"ENVIRONMENT VARIABLES:
                          hostnames to use when fetching remote modules from
                          private repositories
                          (e.g. "abcde12345@deno.land;54321edcba@github.com")
-    DENO_TLS_CA_STORE    Comma-separated list of order dependent certificate stores
-                         (system, mozilla)
-                         (defaults to mozilla)
+    DENO_CACHED_ONLY     Only use already downloaded modules from cache.
     DENO_CERT            Load certificate authority from PEM encoded file
     DENO_DIR             Set the cache directory
     DENO_INSTALL_ROOT    Set deno install's output directory
                          (defaults to $HOME/.deno/bin)
+    DENO_TLS_CA_STORE    Comma-separated list of order dependent certificate stores
+                         (system, mozilla)
+                         (defaults to mozilla)
     DENO_WEBGPU_TRACE    Directory to use for wgpu traces
     HTTP_PROXY           Proxy address for HTTP requests
                          (module downloads, fetch)

cli/proc_state.rs

@@ -175,7 +175,8 @@ impl ProcState {
       eprintln!("{}", colors::yellow(msg));
     }
 
-    let cache_usage = if flags.cached_only {
+    let cache_usage = if flags.cached_only || binary_env_var("DENO_CACHED_ONLY")
+    {
       CacheSetting::Only
     } else if !flags.cache_blocklist.is_empty() {
       CacheSetting::ReloadSome(flags.cache_blocklist.clone())
@@ -695,3 +696,21 @@ fn source_map_from_code(code: String) -> Option<Vec<u8>> {
     None
   }
 }
+
+fn binary_env_var(name: &str) -> bool {
+  if let Ok(v) = env::var(name) {
+    if v == "1" {
+      true
+    } else if v == "0" {
+      false
+    } else {
+      eprintln!(
+        "env var '{}' has a bad value '{}'. Use '1' or '0'.",
+        name, v
+      );
+      std::process::exit(1);
+    }
+  } else {
+    false
+  }
+}

cli/tests/integration/run_tests.rs

@@ -2355,6 +2355,54 @@ fn issue12453() {
   assert!(status.success());
 }
 
+#[test]
+fn cached_only_env() {
+  let _g = util::http_server();
+  let deno_dir = util::new_deno_dir();
+
+  // First run with DENO_CACHED_ONLY=1 should fail, because nothing is cached.
+  let output = util::deno_cmd_with_deno_dir(deno_dir.path())
+    .current_dir(util::testdata_path())
+    .env("DENO_CACHED_ONLY", "1")
+    .arg("run")
+    .arg("--reload")
+    .arg("http://127.0.0.1:4545/019_media_types.ts")
+    .stderr(std::process::Stdio::piped())
+    .spawn()
+    .unwrap()
+    .wait_with_output()
+    .unwrap();
+  assert!(!output.status.success());
+  let stderr = std::str::from_utf8(&output.stderr).unwrap();
+  assert!(stderr.contains("Specifier not found in cache"));
+
+  // Now cache the program.
+  let status = util::deno_cmd_with_deno_dir(deno_dir.path())
+    .current_dir(util::testdata_path())
+    .arg("cache")
+    .arg("http://127.0.0.1:4545/019_media_types.ts")
+    .spawn()
+    .unwrap()
+    .wait()
+    .unwrap();
+  assert!(status.success());
+
+  // Run again with DENO_CACHED_ONLY=1, it should succeed.
+  let status = util::deno_cmd_with_deno_dir(deno_dir.path())
+    .current_dir(util::testdata_path())
+    .env("DENO_CACHED_ONLY", "1")
+    .arg("run")
+    .arg("--reload")
+    .arg("http://127.0.0.1:4545/019_media_types.ts")
+    .stderr(std::process::Stdio::null())
+    .stdout(std::process::Stdio::null())
+    .spawn()
+    .unwrap()
+    .wait()
+    .unwrap();
+  assert!(status.success());
+}
+
 /// Regression test for https://github.com/denoland/deno/issues/12740.
 #[test]
 fn issue12740() {

cli/tests/testdata/035_cached_only_flag.out

@@ -1 +1 @@
-error: Specifier not found in cache: "http://127.0.0.1:4545/019_media_types.ts", --cached-only is specified.
+error: Specifier not found in cache: "http://127.0.0.1:4545/019_media_types.ts", --cached-only or DENO_CACHED_ONLY is specified.