fix CI: skip prereq check for mock backend, add bash to opensuse

- Add KARAPACE_SKIP_PREREQS=1 env var check to skip runtime prerequisite
  checks (user namespaces, fuse-overlayfs) when testing with mock backend
- Set KARAPACE_SKIP_PREREQS=1 in CLI integration test helper
- Add bash to opensuse/tumbleweed container deps (required by
  dtolnay/rust-toolchain action)

.github/workflows/ci.yml

@@ -64,7 +64,7 @@ jobs:
         run: dnf install -y gcc make curl
       - name: Install build deps (openSUSE)
         if: matrix.os == 'opensuse'
-        run: zypper install -y gcc make curl gzip tar xz
+        run: zypper install -y gcc make curl gzip tar xz bash
       - uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: ${{ env.RUST_TOOLCHAIN }}
@@ -136,7 +136,7 @@ jobs:
             setup: "dnf install -y gcc make curl fuse-overlayfs fuse3 crun"
           - os: opensuse
             container: opensuse/tumbleweed:latest
-            setup: "zypper install -y gcc make curl fuse-overlayfs gzip tar xz crun"
+            setup: "zypper install -y gcc make curl fuse-overlayfs gzip tar xz bash crun"
     container: ${{ matrix.container }}
     steps:
       - uses: actions/checkout@v4

crates/karapace-cli/src/main.rs

@@ -203,7 +203,7 @@ fn main() -> ExitCode {
             | Commands::Exec { .. }
             | Commands::Rebuild { .. }
     );
-    if needs_runtime {
+    if needs_runtime && std::env::var("KARAPACE_SKIP_PREREQS").as_deref() != Ok("1") {
         let missing = karapace_runtime::check_namespace_prereqs();
         if !missing.is_empty() {
             eprintln!("error: {}", karapace_runtime::format_missing(&missing));

crates/karapace-cli/tests/cli_integration.rs

@@ -6,7 +6,10 @@
 use std::process::Command;
 
 fn karapace_bin() -> Command {
-    Command::new(env!("CARGO_BIN_EXE_karapace"))
+    let mut cmd = Command::new(env!("CARGO_BIN_EXE_karapace"));
+    // Skip runtime prerequisite checks — mock backend does not need user namespaces
+    cmd.env("KARAPACE_SKIP_PREREQS", "1");
+    cmd
 }
 
 fn temp_store() -> tempfile::TempDir {