File System Mount

Container Root Filesystem

For linux platform, the default mounts points are bind mounting host's /lib, /lib64, /usr, /bin, /etc/ld.so.cache, /etc/alternatives, /etc/fpc.cfg, /dev/null, /dev/urandom, /dev/random, /dev/zero, /dev/full and mounts tmpfs at /w, /tmp and creates /proc.

To customize mount points, please look at example mount.yaml file.

tmpfs size for /w and /tmp is configured through -tmp-fs-param with default value size=128m,nr_inodes=4k

If a file named /.env exists in the container rootfs, the container will load the file as environment variable line by line.

If a bind mount is specifying a target within the previous mounted one, please ensure the target exists in the previous mount point.

Customization

mount.yaml

mount:
  # Basic binaries and libraries
  - type: bind
    source: /bin
    target: /bin
    readonly: true
  - type: bind
    source: /lib
    target: /lib
    readonly: true
  - type: bind
    source: /lib64
    target: /lib64
    readonly: true
  - type: bind
    source: /usr
    target: /usr
    readonly: true
  - type: bind
    source: /etc/ld.so.cache
    target: /etc/ld.so.cache
    readonly: true
  # Some compiler have multiple versions
  - type: bind
    source: /etc/alternatives
    target: /etc/alternatives
    readonly: true
  # fpc wants /etc/fpc.cfg
  - type: bind
    source: /etc/fpc.cfg
    target: /etc/fpc.cfg
    readonly: true
  # mono wants /etc/mono
  - type: bind
    source: /etc/mono
    target: /etc/mono
    readonly: true
  # ghc wants /var/lib/ghc
  - type: bind
    source: /var/lib/ghc
    target: /var/lib/ghc
    readonly: true
  # go wants /dev/null
  - type: bind
    source: /dev/null
    target: /dev/null
  # java 17 wants /etc/java-17-openjdk
  - type: bind
    source: /etc/java-17-openjdk
    target: /etc/java-17-openjdk
    readonly: true
  # node wants /dev/urandom
  - type: bind
    source: /dev/urandom
    target: /dev/urandom
  # additional devices
  - type: bind
    source: /dev/random
    target: /dev/random
  - type: bind
    source: /dev/zero
    target: /dev/zero
  - type: bind
    source: /dev/full
    target: /dev/full
  # work dir
  - type: tmpfs
    target: /w
    data: size=128m,nr_inodes=4k
  # tmp dir
  - type: tmpfs
    target: /tmp
    data: size=128m,nr_inodes=4k
  # MPI wants shm
  # - type: tmpfs
  #   target: /dev/shm
  #   data: size=64m,nr_inodes=4k
  # (optional) bind a /etc/passwd to show customized user name
  - type: bind
    source: containerPasswd.txt
    target: /etc/passwd
  # (optional) bind a /.env to load default environment variable for the container
  - type: bind
    source: dotenv
    target: /.env
    #readonly: true
  # MPI wants /sys, readonly may not work for /sys
  # - type: bind
  #   source: /sys
  #   target: /sys
  #  # readonly: true
# java & ghc wants /proc/self/exe
proc: true
# procrw enables read-write permission on /proc for special usage like CUDA
#procrw: true
# create /dev standard io
symLink:
  - linkPath: /dev/fd
    target: /proc/self/fd
  - linkPath: /dev/stdin
    target: /proc/self/fd/0
  - linkPath: /dev/stdout
    target: /proc/self/fd/1
  - linkPath: /dev/stderr
    target: /proc/self/fd/2
# mask mounted paths with empty / null mount
maskPath:
  - /sys/firmware
  - /sys/devices/virtual/powercap
  - /proc/acpi
  - /proc/asound
  - /proc/kcore
  - /proc/keys
  - /proc/latency_stats
  - /proc/timer_list
  - /proc/timer_stats
  - /proc/sched_debug
  - /proc/scsi
  - /usr/lib/wsl/drivers
  - /usr/lib/wsl/lib
# container work directory
workDir: /w
# container host name
hostName: go-judge
# container domain name
domainName: go-judge
# container user uid
uid: 1536
# container user gid
gid: 1536
# init cmd does additional setups
# MPI want network
#initCmd: ip link set dev lo up

Special Files

containerPasswd.txt

root:x:0:0::/w:/bin/bash
go-judge:x:1536:1536::/w:/bin/bash

dotenv

# /.env file should contain environment variable line by line
# empty line or line start with # are ignored
# double quote is not parsed and should not be used
TESTENV=true