From e7b5d867d02265bae0d7a95318bb11448a0ab7eb Mon Sep 17 00:00:00 2001
From: Justin Trudell <jtru@meta.com>
Date: Wed, 4 Dec 2024 17:17:53 -0800
Subject: [PATCH] [antlir2] Use disk for /tmp during rpm builds

Summary:
See https://fb.workplace.com/groups/codetestingqa/posts/9412044228875340/ -- this is causing issues on Sandcastle for some RPMs. Opt to broadly move to disk as I expect the perf cost to be minimal (we're just dumping artifacts into here post-build, not really doing a significant amount of I/O).

I'll land this after the freeze.

Test Plan:
```
$ buck2 run mode/opt -c antlir.rc_targets=all //registry/builder/rpm/tests:fb-rpm-builder-test.base -- --no-publish
...
BUILD SUCCEEDED
{
  "linux": {
    "aarch64": {
      "primary": "/data/users/jtru/fbsource/buck-out/v2/gen/fbcode/7377c200435b9daa/registry/builder/rpm/tests/__fb-rpm-builder-test.base--rpm-stripped--aarch64__/fb-rpm-builder-test.base--rpm-stripped--aarch64.rpm",
      "debug": "/data/users/jtru/fbsource/buck-out/v2/gen/fbcode/7377c200435b9daa/registry/builder/rpm/tests/__fb-rpm-builder-test.base--rpm-debuginfo--aarch64__/fb-rpm-builder-test.base--rpm-debuginfo--aarch64.rpm"
    },
    "x86_64": {
      "primary": "/data/users/jtru/fbsource/buck-out/v2/gen/fbcode/fc0450a833f3ffe7/registry/builder/rpm/tests/__fb-rpm-builder-test.base--rpm-stripped--x86_64__/fb-rpm-builder-test.base--rpm-stripped--x86_64.rpm",
      "debug": "/data/users/jtru/fbsource/buck-out/v2/gen/fbcode/fc0450a833f3ffe7/registry/builder/rpm/tests/__fb-rpm-builder-test.base--rpm-debuginfo--x86_64__/fb-rpm-builder-test.base--rpm-debuginfo--x86_64.rpm"
    }
  }
}
```

Reviewed By: naveedgol

Differential Revision: D66508035

fbshipit-source-id: a10854694a03353e824440fc8778dfbce469cdbc
---
 antlir/antlir2/antlir2_packager/src/rpm.rs | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/antlir/antlir2/antlir2_packager/src/rpm.rs b/antlir/antlir2/antlir2_packager/src/rpm.rs
index e98e175461c..a78d86d0350 100644
--- a/antlir/antlir2/antlir2_packager/src/rpm.rs
+++ b/antlir/antlir2/antlir2_packager/src/rpm.rs
@@ -26,7 +26,6 @@ use nix::unistd::Group;
 use nix::unistd::Uid;
 use nix::unistd::User;
 use serde::Deserialize;
-use tempfile::NamedTempFile;
 
 use crate::run_cmd;
 use crate::BuildAppliance;
@@ -330,18 +329,18 @@ AutoProv: {autoprov}
             spec.push_str(extra_file);
             spec.push('\n');
         }
-        let mut rpm_spec_file =
-            NamedTempFile::new().context("failed to create tempfile for rpm spec")?;
-        rpm_spec_file
-            .write(spec.as_bytes())
-            .context("while writing rpm spec file")?;
 
         let output_dir = tempfile::tempdir().context("while creating temp dir for rpm output")?;
-
         // create the arch-specific output dir explicitly so that it'll be
         // owned by the build user on the host, not root
         std::fs::create_dir(output_dir.path().join(arch)).context("while creating output dir")?;
 
+        // Note we use a standard dir for /tmp rather than tmpfs because we write full
+        // build artifacts here, and can thus easily run out of ramdisk
+        let tmp = tempfile::tempdir().context("while creating temp dir for rpm build")?;
+        let rpm_spec_file = tmp.path().join("rpmspec");
+        std::fs::write(rpm_spec_file, spec.as_bytes()).context("while writing rpm spec file")?;
+
         let mut isol_context = IsolationContext::builder(self.build_appliance.path());
         isol_context
             .ephemeral(false)
@@ -353,10 +352,9 @@ AutoProv: {autoprov}
                 std::env::current_dir()?,
             ))
             .working_directory(Path::new("/__antlir2__/working_directory"))
-            .inputs((Path::new("/tmp/rpmspec"), rpm_spec_file.path()))
             .inputs((Path::new("/__antlir2__/root"), layer))
             .outputs((Path::new("/__antlir2__/out"), output_dir.path()))
-            .tmpfs(Path::new("/tmp"))
+            .outputs((Path::new("/tmp"), tmp.path()))
             .tmpfs(Path::new("/dev"))
             .inputs(Path::new("/dev/null"));
         #[cfg(facebook)]