MongoDB warns that vm.max_map_count is too low

[ocafebabe]

Issue Description

I get a warning regarding vm.max_map_count when launching a new MongoDB 6.0.15 container using podman.

Steps to reproduce the issue

Steps to reproduce the issue

1. podman run --name mongo --rm -p 27018:27017 -d mongo:6.0
2. mongosh --port 27018 --host localhost
3. (look at the latest warning under: "The server generated these startup warnings when booting")

Describe the results you received

The first 2 warnings are expected because I'm not using an XFS filesystem and didn't configure any security, but the third one shouldn't be there:

------
   The server generated these startup warnings when booting
   2024-05-31T00:19:51.658+00:00: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine. See http://dochub.mongodb.org/core/prodnotes-filesystem
   2024-05-31T00:19:51.933+00:00: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
   2024-05-31T00:19:51.933+00:00: vm.max_map_count is too low
------

Describe the results you expected

No warning regarding vm.max_map_count as it's really high by default on Ubuntu 24.04 (1048576).

podman info output

host:
  arch: amd64
  buildahVersion: 1.33.5
  cgroupControllers:
  - cpu
  - memory
  - pids
  cgroupManager: systemd
  cgroupVersion: v2
  conmon:
    package: conmon_2.1.10+ds1-1build2_amd64
    path: /usr/bin/conmon
    version: 'conmon version 2.1.10, commit: unknown'
  cpuUtilization:
    idlePercent: 99.55
    systemPercent: 0.2
    userPercent: 0.25
  cpus: 4
  databaseBackend: sqlite
  distribution:
    codename: noble
    distribution: ubuntu
    version: "24.04"
  eventLogger: journald
  freeLocks: 2045
  hostname: my-vm
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
  kernel: 6.8.0-31-generic
  linkmode: dynamic
  logDriver: journald
  memFree: 2595860480
  memTotal: 4105641984
  networkBackend: netavark
  networkBackendInfo:
    backend: netavark
    dns:
      package: aardvark-dns_1.4.0-5_amd64
      path: /usr/lib/podman/aardvark-dns
      version: aardvark-dns 1.4.0
    package: netavark_1.4.0-4_amd64
    path: /usr/lib/podman/netavark
    version: netavark 1.4.0
  ociRuntime:
    name: crun
    package: crun_1.14.1-1_amd64
    path: /usr/bin/crun
    version: |-
      crun version 1.14.1
      commit: de537a7965bfbe9992e2cfae0baeb56a08128171
      rundir: /run/user/1000/crun
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +WASM:wasmedge +YAJL
  os: linux
  pasta:
    executable: /usr/bin/pasta
    package: passt_0.0~git20240220.1e6f92b-1_amd64
    version: |
      pasta unknown version
      Copyright Red Hat
      GNU General Public License, version 2 or later
        <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
      This is free software: you are free to change and redistribute it.
      There is NO WARRANTY, to the extent permitted by law.
  remoteSocket:
    exists: false
    path: /run/user/1000/podman/podman.sock
  security:
    apparmorEnabled: false
    capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
    rootless: true
    seccompEnabled: true
    seccompProfilePath: /usr/share/containers/seccomp.json
    selinuxEnabled: false
  serviceIsRemote: false
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: slirp4netns_1.2.1-1build2_amd64
    version: |-
      slirp4netns version 1.2.1
      commit: 09e31e92fa3d2a1d3ca261adaeb012c8d75a8194
      libslirp: 4.7.0
      SLIRP_CONFIG_VERSION_MAX: 4
      libseccomp: 2.5.5
  swapFree: 4105170944
  swapTotal: 4105170944
  uptime: 0h 39m 56.00s
  variant: ""
plugins:
  authorization: null
  log:
  - k8s-file
  - none
  - passthrough
  - journald
  network:
  - bridge
  - macvlan
  - ipvlan
  volume:
  - local
registries: {}
store:
  configFile: /home/myuser/.config/containers/storage.conf
  containerStore:
    number: 1
    paused: 0
    running: 1
    stopped: 0
  graphDriverName: overlay
  graphOptions: {}
  graphRoot: /home/myuser/.local/share/containers/storage
  graphRootAllocated: 33632829440
  graphRootUsed: 8830066688
  graphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
    Supports shifting: "false"
    Supports volatile: "true"
    Using metacopy: "false"
  imageCopyTmpDir: /var/tmp
  imageStore:
    number: 1
  runRoot: /run/user/1000/containers
  transientStore: false
  volumePath: /home/myuser/.local/share/containers/storage/volumes
version:
  APIVersion: 4.9.3
  Built: 0
  BuiltTime: Thu Jan  1 00:00:00 1970
  GitCommit: ""
  GoVersion: go1.22.1
  Os: linux
  OsArch: linux/amd64
  Version: 4.9.3

Podman in a container

No

Privileged Or Rootless

Rootless

Upstream Latest Release

No

Additional environment details

This was tested on a vanilla Ubuntu Server 24.04 LTS with the default value of max_map_count:

cat /proc/sys/vm/max_map_count
1048576

Additional information

Please note that I don't get this warning when running a standalone MongoDB instance on the same server:

Current Mongosh Log ID:	665918c756b78c6261a26a12
Connecting to:		mongodb://localhost:27017/?directConnection=true&serverSelectionTimeoutMS=2000&appName=mongosh+2.2.6
Using MongoDB:		6.0.15
Using Mongosh:		2.2.6

For mongosh info see: https://docs.mongodb.com/mongodb-shell/

------
   The server generated these startup warnings when booting
   2024-05-30T23:51:41.974+00:00: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine. See http://dochub.mongodb.org/core/prodnotes-filesystem
   2024-05-30T23:51:42.270+00:00: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
------

[Luap99]

This is not something podman can change, AFAIK the value is the same on the host and contianer as it is not namesapced at all

$ podman run quay.io/libpod/testimage:20240123 cat /proc/sys/vm/max_map_count
1048576
$ cat /proc/sys/vm/max_map_count
1048576

You should ask the mongo folks what value they are expecting.

[ocafebabe]

Like I said earlier, the value is already high enough and I don't get the same error when launching Mongo on the same host (non-containerized), so it looks like a container issue.