Isolation & Security

niso provides Docker-equivalent (and stronger) isolation using systemd directives. Six presets cover common workloads, with full field-level override.

Isolation presets#

Every package declares an isolation preset in manifest.toml. Presets configure namespaces, seccomp, capabilities, and filesystem protection in one line.

Preset	DynamicUser	Seccomp	Caps	Use case
`none`	—	—	all	Testing only
`minimal`	—	default	most	Legacy apps needing root
`server`	yes	default	zero	HTTP APIs, web services
`strict`	yes	strict	zero	Untrusted code, security-critical
`worker`	yes	default	zero	Background jobs, queue consumers
`database`	yes	default	zero	Databases (I/O tuning, IPC)

What "server" preset enables

The default server preset generates these systemd directives:

niso-my-api.service (generated)

[Service]DynamicUser=yesPrivateTmp=yesPrivateDevices=yesPrivateIPC=yesProtectSystem=strictProtectHome=yesProtectProc=invisibleProcSubset=pidProtectKernelTunables=yesProtectKernelModules=yesProtectKernelLogs=yesProtectControlGroups=yesProtectHostname=yesProtectClock=yesRestrictNamespaces=yesRestrictRealtime=yesRestrictSUIDSGID=yesNoNewPrivileges=yesCapabilityBoundingSet=AmbientCapabilities=SystemCallFilter=@system-serviceSystemCallErrorNumber=EPERMLockPersonality=yesMemoryDenyWriteExecute=yes

Overriding presets#

Presets are a starting point. You can override any field:

manifest.toml

[isolation]preset = "server"[isolation.security]# Add back NET_BIND_SERVICE to bind port 80capabilities_add = ["NET_BIND_SERVICE"][isolation.resources]memory_max = "1G"cpu_max = "400%"

Namespaces#

niso isolates each service in its own PID, mount, network, IPC, and UTS namespace. The host's process tree, filesystem, and network are invisible to the service.

PID — process sees only its own tree (PID 1)
Mount — assembled rootfs via RootDirectory
Network — veth pair in a bridge network
IPC — private SysV IPC and POSIX message queues
UTS — isolated hostname

Seccomp filtering#

Seccomp restricts which system calls the process can make. niso supports three profiles:

default — systemd's @system-service set. Blocks dangerous calls like ptrace, personality, mount.
strict — tighter filter. Blocks socket (except AF_INET/AF_INET6/AF_UNIX), clone with new namespaces, and more.
custom — provide a path to your own seccomp BPF profile.

Capabilities#

By default, niso drops all Linux capabilities. This is stricter than Docker, which keeps several by default. Add back only what your application needs:

toml

[isolation.security]capabilities_add = [  "NET_BIND_SERVICE",  # Bind ports below 1024  "SYS_PTRACE",        # For debugging tools]

Resource limits#

Control CPU, memory, I/O, and process count using cgroups v2:

toml

[isolation.resources]memory_max = "512M"       # Hard limit (OOM kill)memory_high = "384M"      # Soft limit (throttle)cpu_max = "200%"          # 2 CPU corespids_limit = 4096         # Max processesshm_size = "64M"          # /dev/shm sizeio_weight = 100           # I/O priority (1-10000)[isolation.resources.ulimits]nofile = { soft = 65536, hard = 65536 }

Filesystem protection#

Each service runs in an assembled rootfs. The host filesystem is invisible. Volume mounts use nosuid,nodev,nosymfollowflags to prevent escapes:

ProtectSystem=strict — entire filesystem is read-only
ProtectHome=yes — /home is inaccessible
PrivateTmp=yes — isolated /tmp
PrivateDevices=yes — no access to physical devices

Inspecting isolation#

bash

# Show effective isolation config$ niso isolation show my-api  Preset:       server  DynamicUser:  yes  Seccomp:      @system-service  Capabilities: none  Memory:       512M (max), 384M (high)  CPU:          200%  PIDs:         4096# Validate kernel support$ niso isolation check my-api  ✓ cgroups v2 supported  ✓ seccomp available  ✓ user namespaces enabled  ✓ All isolation features supported

Trust policies#

Configure trust policies in /etc/niso/niso.toml to require package signatures and restrict which signers can publish which packages:

/etc/niso/niso.toml

[trust]require_signatures = true[[trust.signers]]name = "official"public_key = "/etc/niso/trusted-keys/official.pub"scope = ["*"][[trust.signers]]name = "team"public_key = "/etc/niso/trusted-keys/team.pub"scope = ["my-*", "internal-*"]