[docker-up] Configure docker0 MTU

[aledbf]

Description

Configure the docker network control plane MTU (docker0)

How to test

• Start a workspace
• Run docker run -it alpine
• Run ip a s and check the MTU of the docker0 interface is the same than ceth0
• Kill the container and check the docker0 MTU is 1500

Release Notes

[docker-up] Configure docker0 MTU

[princerachit]

Seeing error when starting workspace

[aledbf]

@princerachit that looks like a core-dev issue, not related to the change

[princerachit]

@aledbf I am approving this PR as the changes LGTM. Feel free to remove the hold tag (unless you want someone to test this PR)

/hold

[aledbf]

/werft run with-clean-slate

👍 started the job as gitpod-build-aledbf-up.1
(with .werft/ from main)

[aledbf]

/werft run

👍 started the job as gitpod-build-aledbf-up.2
(with .werft/ from main)

[aledbf]

/werft run with-clean-slate

👍 started the job as gitpod-build-aledbf-up.3
(with .werft/ from main)

[csweichel]

/werft run no-preview

👍 started the job as gitpod-build-aledbf-up.4
(with .werft/ from main)

[aledbf]

It seems docker0 is not using the new value when there is no container/s running

agitpod /workspace/template-python-flask (main) $ ip a s
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: tunl0@NONE: <NOARP> mtu 1480 qdisc noop state DOWN group default qlen 1000
    link/ipip 0.0.0.0 brd 0.0.0.0
3: ceth0@if5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1440 qdisc noqueue state UP group default 
    link/ether 5a:fc:4f:24:5a:95 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 10.0.5.2/24 brd 10.0.5.255 scope global ceth0
       valid_lft forever preferred_lft forever
    inet6 fe80::58fc:4fff:fe24:5a95/64 scope link 
       valid_lft forever preferred_lft forever
4: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1440 qdisc noqueue state UP group default 
    link/ether 02:42:d9:10:77:55 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:d9ff:fe10:7755/64 scope link 
       valid_lft forever preferred_lft forever
14: veth55f19f4@if13: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1440 qdisc noqueue master docker0 state UP group default 
    link/ether 36:4c:3f:35:2b:a7 brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet6 fe80::344c:3fff:fe35:2ba7/64 scope link 
       valid_lft forever preferred_lft forever