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Release 0.76#

2026-06-03 ยท Full Changelog

NVIDIA Cumulus VX VM#

The nvidia_cumulusvx kind brings Cumulus VX back through a VM-based workflow and sunsets the container-based cvx kind. Use a containerlab-compatible image built from the original qcow2 image with vrnetlab or boxen-v2, and model dataplane interfaces as swpN ports that match the Cumulus configuration.

While NVIDIA does not distribute the Cumulus VX image anymore through their developer's portal, the sneaky petes always find a way to get their hands on a qcow2.

Thanks @BurlyLuo #3209

Remote startup-config and license files#

Node artifacts do not have to live on the lab host anymore. The startup-config and license fields can now use local files, embedded blobs, or remote URLs. Remote downloads support https, http, S3, ftp, sftp, and scp.

topology:
  nodes:
    srl1:
      startup-config: sftp://user@example.com/configs/srl1.partial.cfg
      license: https://licenses.example.com/srl1/license.key

For sftp and scp, password authentication can be provided in the URL, key-based authentication uses CLAB_SSH_KEY and CLAB_SSH_KEY_PASSPHRASE, and SSH_AUTH_SOCK is used when an SSH agent is available.

Thanks @steiler @FloSch62 #1414

Containerlab GUI documentation#

The GUI docs have been rebuilt around the shared TopoViewer workflow, with dedicated pages for the VS Code extension, Desktop app, Web app, and browser sandbox.

The new Containerlab GUI section explains how the Explorer, topology editor, layouts, annotations, packet capture, link impairments, image management, and Grafana bundle export fit together. The API server docs were added alongside it for Desktop and Web deployments.

Thanks @FloSch62 #3206

Management network controls#

Labs that intentionally run all nodes with network-mode: none can set mgmt.skip-when-unused: true to avoid creating an unused management network and empty /etc/hosts marker block.

The management-network docs also cover a local-only setup for labs that should keep host-to-container and container-to-container communication while preventing external network access through the management bridge.

Thanks @torbbang @mlaga97 #3191 #3188

Miscellaneous#

  • Concurrent deployments on the same host are more reliable thanks to safer /etc/hosts lab block handling and Docker network checks. Thanks @torbbang #3190
  • Docker container start now retries the transient IPv6 gateway file exists failure. Thanks @micyen #3185
  • Topology schema validation now requires link endpoints and includes the top-level debug field. Thanks @alexandrehassan #3199
  • Added missing SR Linux IXR models and SR-SIM SAR chassis types to the schema. Thanks @ripnet @sacckth #3196 #3184
  • SR Linux and SONiC lab example docs were refreshed with current version information and configuration. Thanks @fatred #3183
  • DOT graph output now quotes graph names correctly. Thanks @fabriciojm #3202
  • Interface altname setup now warns and continues on kernels that do not support altnames. #3205
  • Lifecycle handling for links and SR-SIM nodes was simplified and covered with additional SR-SIM lifecycle tests. Thanks @kaelemc #3195
  • Containerlab now builds with Go 1.25. #3193