Avoid rebuilding containers unnecessarily to reduce job run time.

Change-Id: Ibd3734824a4fe129dee6f0d3040765215e40fcb4

justfile

@@ -157,7 +157,7 @@ all_ensure_no_std: (ensure_no_std "micro_rpc") (ensure_no_std "oak_attestation_v
 kokoro_build_binaries_rust: all_enclave_apps oak_restricted_kernel_bin oak_restricted_kernel_simple_io_init_rd_wrapper stage0_bin
 
 kokoro_oak_containers: all_oak_containers_binaries oak_functions_containers_container_bundle_tar
-    RUST_LOG="debug" cargo nextest run --all-targets --hide-progress-bar --package='oak_containers_hello_world_untrusted_app'
+    OAK_CONTAINERS_BINARIES_ALREADY_BUILT=1 RUST_LOG="debug" cargo nextest run --all-targets --hide-progress-bar --package='oak_containers_hello_world_untrusted_app'
 
 kokoro_run_tests: all_ensure_no_std
     RUST_LOG="debug" cargo nextest run --all-targets --hide-progress-bar --workspace --exclude='oak_containers_hello_world_untrusted_app'

oak_containers_hello_world_untrusted_app/tests/integration_test.rs

@@ -15,7 +15,7 @@
 
 //! Integration test that launches the trusted app and invokes it.
 
-use std::sync::Once;
+use std::{env, sync::Once};
 
 use oak_client::verifier::{AttestationVerifier, InsecureAttestationVerifier};
 use oak_containers_launcher::{proto::oak::key_provisioning::v1::GetGroupKeysRequest, Args};
@@ -33,9 +33,14 @@ fn init_logging() {
 }
 
 static INIT_DEPENDENCIES: Lazy<anyhow::Result<()>> = Lazy::new(|| {
-    // This takes a long time, but we want to make sure everything it up to date.
-    // TODO(#4195): Stop dependencies from always being rebuilt.
-    duct::cmd!("just", "all_oak_containers_binaries",).dir(env!("WORKSPACE_ROOT")).run()?;
+    if env::var("OAK_CONTAINERS_BINARIES_ALREADY_BUILT").unwrap_or_default().is_empty() {
+        log::info!("Rebuilding all_oak_containers_binaries.");
+        log::info!(
+            "To prevent this, set the OAK_CONTAINERS_BINARIES_ALREADY_BUILT environment variable."
+        );
+        duct::cmd!("just", "all_oak_containers_binaries",).dir(env!("WORKSPACE_ROOT")).run()?;
+    }
+
     Ok(())
 });