support mtu change

[james-martinez]

---

• [X] I have read the contributing guideline and understand that I have made the correct modifications

---

Description:

This PR supports Kasm deployed into Kubernetes and other virtualized networking that requires a mtu change from the dockerd default of 1500

Benefits of this PR and context:

When Kasm deploys "workspaces" dind is used. Downloads hang and timeout and its because of the "overlayed" mtu set in the primary networking interface. eth0 (1500) -> cni0 (eg. 1450) -> docker0(1500)

How Has This Been Tested?

Used images built in CI and verified options are passed and configured correctly. docker inspect network bridge[hash] and docker exec "dev container hash" ps aux

Source / References:

https://blog.zespre.com/dind-mtu-size-matters.html https://bascht.com/tech/2021/04/08/kubernetes-docker-dind-mtu-issues-on-hetzner-cloud/

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[james-martinez]

Need to find where config of kasm network bridge kasm_default_network.

NETWORK ID     NAME                   DRIVER    SCOPE
353f7187f6d1   bridge                 bridge    local
3564103f2412   host                   host      local
8d3cb6e06eed   kasm_default_network   bridge    local
5ad5d5c85024   none                   null      local

bridge, bridge mtu options are set. docker network inspect 353

        "Options": {
            "com.docker.network.bridge.default_bridge": "true",
            "com.docker.network.bridge.enable_icc": "true",
            "com.docker.network.bridge.enable_ip_masquerade": "true",
            "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
            "com.docker.network.bridge.name": "docker0",
            "com.docker.network.driver.mtu": "1300"
        }

kasm options are blank docker network inspect 8d3

"Options": {}

Docker compose yaml file found: /opt/kasm/1.13.0/docker/docker-compose.yaml

networks:
  kasm_default_network:
    external: true

Looks to be a feature request and should configure mtu on own network via compose or daemon.json https://docs.docker.com/engine/reference/commandline/network_create/#bridge-driver-options https://docs.docker.com/compose/networking/#use-a-pre-existing-network

[james-martinez]

Fixed issue of kasm_default_network. Now workspaces download content without issues. in install.sh of kasm line 620 docker network create --driver=bridge -o com.docker.network.driver.mtu=1300 kasm_default_network

Asking for advice of sending this issue (kasm_default_network) upstream with kasm or just fixing here.

[james-martinez]

Kasm is able to choose which network to use, until upstream is fixed, the bridge network must be used.

[james-martinez]

Please review and merge for added feature

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