gns3-server/docs/features/iol-runner-docker.md
YueGuobin e272ad915b
feat: add IOL (iol-runner) Docker node support
Run Cisco CML containerized IOL images (e.g. iol-xe/iol-xe:17-18-02,
driven by virl.lab/cmd/iol-runner) as GNS3 Docker router nodes:

- VendorDockerVM: generic GNS3_UNIX_SOCKET_NIO/GNS3_UNIX_SOCKET_DIR knobs
  wiring adapters through AF_UNIX datagram socket pairs
  (add_nio_unix cNN.sock sNN.sock) instead of TAP + move_to_ns; node
  creation fails if the socket dir is not a persisted volume.
- IOLDockerVM (GNS3_IOL_RUNNER=1): forces skip-init + unix-socket NIO +
  /config,/tmp volumes, writes iol-config.json on every start (num-eth
  tracks adapters, runner drops to the server uid/gid so the sockets are
  reachable), pre-creates tmp/run, cleans stale sockets after unclean
  kills, and makes reload a graceful stop + full start (NVRAM flush +
  rewiring). Console stays telnet on PID 1 stdio.
- Manager selects the node class from console_type or GNS3_* environment
  markers (create-time, like console_type).
- Image-free tests (25) and feature documentation.
2026-09-05 21:54:12 +08:00

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> This documentation is organized by AI with reference to actual code. AI can make mistakes — please verify against the source code when in doubt.
# IOL Images with iol-runner (Cisco CML containerized IOL) as Docker Nodes
## Overview
IOL images packaged with Cisco CML's container runner — for example
`iol-xe/iol-xe:17-18-02` (IOS-XE 17.18.02 IOL in a scratch image driven by
`iol-runner`, module `virl.lab/cmd/iol-runner`) — run as first-class GNS3
Docker router nodes with **zero changes to the image**. The integration adds
two generic server mechanisms:
1. **Unix-socket NIO** (`GNS3_UNIX_SOCKET_NIO=1`, on `VendorDockerVM`): link
adapters through per-interface AF_UNIX datagram sockets instead of a TAP
interface moved into the container's network namespace.
2. **`IOLDockerVM`** (marker `GNS3_IOL_RUNNER=1`): generates the runner's
config file per start, prepares its runtime directory and cleans up stale
sockets — the iol-runner-specific glue on top of the vendor path.
## How the image works
```mermaid
graph LR
subgraph Container["scratch container (PID 1)"]
RUNNER["/iol-runner -config /config/iol-config.json -stdio"]
IOL["IOL process<br/>(IOS-XE 17.18.02)"]
NETIOMUX["netiomux"]
SOCKETS["/tmp/s00.sock (recv)<br/>/tmp/c00.sock (send-to path)<br/>… one pair per interface"]
RUNNER -->|"spawn -e/-s/-m + app id"| IOL
IOL -->|"netio bus /tmp/netio&lt;uid&gt;/"| NETIOMUX --> SOCKETS
end
subgraph Host
UBRIDGE["uBridge bridgeN<br/>add_nio_unix c00.sock s00.sock<br/>+ add_nio_udp (topology)"]
VOL["project-files/docker/&lt;node&gt;/tmp"]
end
SOCKETS <-->|"raw Ethernet frames<br/>(bind volume dir)"| VOL <--> UBRIDGE
```
* **Console**: the runner muxes the IOS console onto PID 1 stdio (`-stdio`
entrypoint flag). The plain `console_type: "telnet"` attaches to it — no
`docker_exec` needed. The runner requires a TTY, which GNS3 always
allocates; without one the runner exits (`inappropriate ioctl for device`).
* **Networking**: the runner does not touch the container's network
namespace. Per interface N it creates, inside `/tmp`: a receive socket
`s%02d.sock` (frames sent there are injected into guest interface N) and a
send-to path `c%02d.sock` (whoever binds it receives the guest's frames).
Frames are **raw Ethernet**, one datagram per frame. Because `/tmp` is a
persisted volume (bind-mounted from the node directory), uBridge can bind
`cNN.sock` and send to `sNN.sock` on the host.
* **Licensing**: the image ships a self-consistent `/etc/hostid` + `.iourc`
pair, and the runner regenerates the license from the host ID at boot —
nothing to configure.
* **Persistence**: `/tmp/run/` inside the volume holds the NETMAP, the
startup-config (`config`, plain IOS format) and NVRAM (`nvram_00001`), so
the router's configuration survives stop/start and container recreation.
The generated config maps the runner to the server's uid/gid
(`user-id`/`group-id`), which is also what makes the `/tmp` sockets
reachable by uBridge and all volume files owned by the server user (no
permission-fix pass needed).
## Template
```json
{
"name": "IOS-XE 17.18.02 IOL",
"template_type": "docker",
"image": "iol-xe/iol-xe:17-18-02",
"category": "router",
"symbol": ":/symbols/router.svg",
"adapters": 4,
"console_type": "telnet",
"environment": "GNS3_IOL_RUNNER=1",
"extra_volumes": ["/config", "/tmp"],
"memory": 2560
}
```
`/config` and `/tmp` are auto-added even if omitted; listing them keeps the
template self-documenting.
## Server mechanisms
| Mechanism | Where | What it does |
|---|---|---|
| `GNS3_UNIX_SOCKET_NIO=1` | `VendorDockerVM` | `_add_ubridge_connection` override: `bridge create` + `bridge add_nio_unix <dir>/c{N:02d}.sock <dir>/s{N:02d}.sock` instead of TAP + `docker move_to_ns`. No TAP allocation, no `set_mac_addr`, namespace untouched. Fails node creation if the socket dir is not a persisted volume. |
| `GNS3_UNIX_SOCKET_DIR=<dir>` | `VendorDockerVM` | Socket directory (default `/tmp`). Any image whose agent exposes the `s%02d`/`c%02d` datagram pairs can use this without the IOL specifics. |
| `GNS3_IOL_RUNNER=1` | `IOLDockerVM` (selected in the manager) | Forces skip-init + unix-socket NIO + the two volumes; on every start writes `<node>/config/iol-config.json` (`num-eth` = adapter count, `num-serial` = 0, memory from `GNS3_IOL_MEMORY`, default 2048), creates `<node>/tmp/run/` (the IOL process dies without it) and removes stale `s/c??.sock` + `netio*` left by an unclean kill (`tmp/run` is never touched). |
| `restart()` hardening | `IOLDockerVM` | The base `docker restart` would boot the runner on a stale config and leave uBridge wired to the previous run's sockets; reload becomes graceful stop (SIGTERM → NVRAM flush) + full start. |
`GNS3_STOP_TIMEOUT` (default 60) controls the SIGTERM grace period on stop.
Extra iol-runner flags can be passed via `start_command`, e.g. `-keep`
(L1 keepalives) or `-debug 9` (verbose `process.log` — very useful when
diagnosing wiring issues).
## Notes and caveats
* **Memory sizing**: `memory` caps the whole container; the IOL process gets
`GNS3_IOL_MEMORY` (default 2048 MB). Keep container memory at IOL memory
+ ~512 MB headroom or the OOM-killer will shoot the router.
* **MAC addresses**: the `mac_address` template field and per-adapter custom
MACs are ignored — IOL derives its own scheme (`aabb.cc00.0XY0`).
* **Adapters**: change the adapter count while the node is stopped; the
config is regenerated on the next start and the runner creates the
matching socket set (IOL granularity is 4 ports per unit).
* **Stop before editing**: NVRAM is only flushed on a graceful stop (SIGTERM,
"cleanup done" in `process.log`); a kill loses the running-config changes
since the last `write memory`.
* **Class selection is create-time**: toggling `GNS3_IOL_RUNNER` via PUT
takes effect after a project reload (same as `docker_exec`).
* The startup-config lives at `project-files/docker/<node>/tmp/run/config`;
`extra_configs` targets under persisted volumes are warned against by the
generic create path — edit the file directly or paste via the console.