xtask: Add --skip-bind-storage to run-tmt

The `--bind-storage-ro` host container-storage passthrough relies on a
libvirt-managed virtiofsd, which cannot run in some environments such as
nested user namespaces or cloud/non-qemu setups. Plans that normally
request bind-storage previously had no way to opt out short of editing
plan metadata.

Add a `--skip-bind-storage` flag (and matching `BOOTC_skip_bind_storage`
env var) that forces those plans to run without the host
container-storage mount. Default behavior is unchanged: bind-storage is
still used wherever it is requested and supported. Plans that depend on a
locally built upgrade image reaching the VM via bind-storage will be
unable to perform the upgrade/switch step when this is set.

Assisted-by: OpenCode (Claude Opus 4.5)
Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

crates/xtask/src/tmt.rs

@@ -456,15 +456,22 @@ pub(crate) fn run_tmt(sh: &Shell, args: &RunTmtArgs) -> Result<()> {
 
             let mut opts = Vec::new();
 
-            // If test wants bind storage and distro supports it, add --bind-storage-ro
-            if try_bind_storage && supports_bind_storage_ro {
+            // If test wants bind storage, the distro supports it, and it wasn't
+            // explicitly disabled, add --bind-storage-ro
+            let use_bind_storage =
+                try_bind_storage && supports_bind_storage_ro && !args.skip_bind_storage;
+            if use_bind_storage {
                 opts.push(BCVK_OPT_BIND_STORAGE_RO.to_string());
 
                 // If upgrade image is provided, set it as an environment variable for tmt
                 // (not bcvk, as bcvk doesn't support --env)
                 if let Some(ref upgrade_img) = args.upgrade_image {
                     tmt_env_vars.push(format!("{}={}", ENV_BOOTC_UPGRADE_IMAGE, upgrade_img));
                 }
+            } else if try_bind_storage && args.skip_bind_storage {
+                println!(
+                    "Note: Test requests bind storage but --skip-bind-storage was set; running without host container-storage mount"
+                );
             } else if try_bind_storage && !supports_bind_storage_ro {
                 println!(
                     "Note: Test wants bind storage but skipping on {} (missing systemd.extra-unit.* support)",

crates/xtask/src/xtask.rs

@@ -45,6 +45,16 @@ fn out_of_sync_error(message: &str) -> Result<()> {
     anyhow::bail!("{}; run `just update-generated` to update it", message)
 }
 
+/// Parse a `0`/`1` boolean from a CLI/env value so the flag can be driven from
+/// the Justfile (e.g. `BOOTC_skip_bind_storage=1`).
+fn parse_cli_bool(s: &str) -> std::result::Result<bool, String> {
+    match s {
+        "1" | "true" => Ok(true),
+        "0" | "false" => Ok(false),
+        other => Err(format!("invalid value '{other}' (expected 0, 1, true, or false)")),
+    }
+}
+
 /// Build tasks for bootc
 #[derive(Debug, Parser)]
 #[command(name = "xtask")]
@@ -228,6 +238,24 @@ pub(crate) struct RunTmtArgs {
     #[clap(long)]
     pub(crate) upgrade_image: Option<String>,
 
+    /// Skip the `--bind-storage-ro` host container-storage virtiofs mount even for
+    /// plans that request it.  Useful where libvirt-managed virtiofsd cannot run
+    /// (nested user namespaces, cloud/non-qemu).  Plans that depend on a locally
+    /// built upgrade image being available in-VM via bind-storage will not be able
+    /// to perform the upgrade/switch step.
+    ///
+    /// Takes `0`/`1`/`true`/`false` so it can be driven from the Justfile via
+    /// `BOOTC_skip_bind_storage=1`.  A bare `--skip-bind-storage` means `1`.
+    #[arg(
+        long,
+        env = "BOOTC_skip_bind_storage",
+        num_args = 0..=1,
+        default_value_t = false,
+        default_missing_value = "1",
+        value_parser = parse_cli_bool,
+    )]
+    pub(crate) skip_bind_storage: bool,
+
     /// Preserve VMs after test completion (useful for debugging)
     #[arg(long)]
     pub(crate) preserve_vm: bool,
@@ -765,3 +793,18 @@ fn validate_composefs_digest(sh: &Shell, args: &ValidateComposefsDigestArgs) ->
         anyhow::bail!("Composefs digest mismatch");
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_cli_bool() {
+        assert_eq!(parse_cli_bool("1"), Ok(true));
+        assert_eq!(parse_cli_bool("true"), Ok(true));
+        assert_eq!(parse_cli_bool("0"), Ok(false));
+        assert_eq!(parse_cli_bool("false"), Ok(false));
+        assert!(parse_cli_bool("").is_err());
+        assert!(parse_cli_bool("maybe").is_err());
+    }
+}