Unable to run planka on unprivilved LXD container can't mount /proc

I am trying to run the following in docker-compose under an alpine container (running docker with a uid map as well). Here is the yaml


services:
  planka:
    image: ghcr.io/plankanban/planka:latest
    restart: on-failure
    volumes:
      - user-avatars:/app/public/user-avatars
      - project-background-images:/app/public/project-background-images
      - attachments:/app/private/attachments
    ports:
      - 127.0.0.1:3000:1337
    environment:
      - BASE_URL=<edacted>
      - DATABASE_URL=postgresql://postgres@postgres/planka
      - SECRET_KEY=<redacted>
      - TRUST_PROXY=1
      - DEFAULT_ADMIN_EMAIL=<redacted>
      - DEFAULT_ADMIN_PASSWORD=<redacted>
      - DEFAULT_ADMIN_NAME=<redacted>
      - DEFAULT_ADMIN_USERNAME=<redacted>
                                                                                                                                                                                                                                                
    depends_on:                                                                                                                                                                                                                                                                                       
      postgres:                                                                                                                                                                                                                                                                                       
        condition: service_healthy                                                                                                                                                                                                                                                                    
                                                                                                                                                                                                                                                                                                      
  postgres:                                                                                                                                                                                                                                                                                           
    image: postgres:16-alpine                                                                                                                                                                                                                                                                         
    restart: on-failure                                                                                                                                                                                                                                                                               
    volumes:                                                                                                                                                                                                                                                                                          
      - db-data:/var/lib/postgresql/data                                                                                                                                                                                                                                                              
    environment:                                                                                                                                                                                                                                                                                      
      - POSTGRES_DB=planka                                                                                                                                                                                                                                                                            
      - POSTGRES_HOST_AUTH_METHOD=trust                                                                                                                                                                                                                                                               
    healthcheck:                                                                                                                                                                                                                                                                                      
      test: ["CMD-SHELL", "pg_isready -U postgres -d planka"]                                                                                                                                                                                                                                         
      interval: 10s                                                                                                                                                                                                                                                                                   
      timeout: 5s                                                                                                                                                                                                                                                                                     
      retries: 5                                                                                                                                                                                                                                                                                      
                                                                                                                                                                                                                                                                                                      
volumes:                                                                                                                                                                                                                                                                                              
  user-avatars:                                                                                                                                                                                                                                                                                       
  project-background-images:                                                                                                                                                                                                                                                                          
  attachments:                                                                                                                                                                                                                                                                                        
  db-data:                                                                                                                                                                                                                                                                                            

Here is the error message:

Error response from daemon: failed to create task for container: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: error mounting "proc" to rootfs at "/proc": mount src=proc, dst=/proc, dstFd=/proc/thread-self/fd/8, flags=MS_NOSUID|MS_NODEV|MS_NOEXEC: operation not permitted

I figured it out. Having docker ‘change’ contexts within an non-privleged container results in this error. Running docker without this (kind of not necessary, since our container is non-privileged anyways) seems to fix it. I would be curious to see if I could do this anyways…