Problem
The SQL Server container fails to start, or its logs show permission denied errors when it writes to the bind-mounted data directory. The SQL Server image runs as the mssql user, UID 10001, GID 0. If the host directory is owned by your login user or by root, that user cannot write to it.
Fix
Create the directories on the host, then give UID 10001 and GID 0 ownership. Choose a data root; $HOME/servers is used here as an example.
DATA_ROOT="$HOME/servers"
MSSQL_DIR="$DATA_ROOT/mssql"
# make the dirs
sudo mkdir -p "$MSSQL_DIR"/{data,log,backup,system}
# give the container user access (UID 10001, GID 0)
sudo chown -R 10001:0 "$MSSQL_DIR"/{data,log,backup,system}
sudo chmod -R 770 "$MSSQL_DIR"/{data,log,backup,system}Then point the container’s bind mounts at $MSSQL_DIR/data, $MSSQL_DIR/log, $MSSQL_DIR/backup, and $MSSQL_DIR/system.
Why
The container process runs as UID 10001 and is not your host login user. Bind mounts keep the host’s ownership, so the container can only write to the directories if UID 10001 owns them or has write permission through the group.