dev: Fix cache directory permissions for nonroot user

Dockerfile

@@ -18,14 +18,15 @@ COPY shared ./shared
 
 RUN cargo build --release
 
-RUN mkdir /stage && cp --parents /usr/lib/$(gcc -print-multiarch)/libzstd.so.1 /stage
+RUN mkdir /stage /synapse-cache && cp --parents /usr/lib/$(gcc -print-multiarch)/libzstd.so.1 /stage
 
 # Runtime stage
 FROM gcr.io/distroless/cc-debian13:nonroot
 WORKDIR /app
 
 COPY --from=builder /app/target/release/synapse synapse
 COPY --from=builder /stage/ /
+COPY --from=builder --chown=nonroot:nonroot /synapse-cache /tmp/synapse-cache
 
 ENTRYPOINT ["/app/synapse"]
 CMD []

devservices/ingest-router.yaml

@@ -12,7 +12,6 @@ ingest_router:
       url: http://host.docker.internal:8000
     backup_route_store:
       type: filesystem
-      base_dir: /tmp/synapse-cache
       filename: backup.bin
       compression: zstd1
     localities:

devservices/proxy.yaml

@@ -11,7 +11,6 @@ proxy:
       url: http://host.docker.internal:8000
     backup_route_store:
       type: filesystem
-      base_dir: /tmp/synapse-cache
       filename: backup.bin
       compression: zstd1
     localities:

locator/src/config.rs

@@ -12,11 +12,16 @@ pub enum Compression {
     Zstd3,
 }
 
+fn default_base_dir() -> String {
+    "/tmp/synapse-cache".into()
+}
+
 #[derive(Clone, Deserialize, Debug, PartialEq)]
 #[serde(rename_all = "snake_case")]
 #[serde(tag = "type")]
 pub enum BackupRouteStoreType {
     Filesystem {
+        #[serde(default = "default_base_dir")]
         base_dir: String,
         filename: String,
         compression: Compression,