Add check for docker engine liveness

odinuge commented 5 years ago

What type of PR is this? /kind cleanup

What this PR does / why we need it:

If docker engine/server is not running, the preflight check will now report:

system validation failed: [unsupported docker version: ]

because the output of docker info --format "{{json .}}" is:

{
  "ServerErrors": [
    "Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?"
  ],
  "ClientInfo": {
    "Debug": false,
    "Plugins": [],
    "Warnings": null
  }
}

With this PR the check will report:

system validation failed: [error when fetching docker info: "Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?"]

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

/assign neolit123

Does this PR introduce a user-facing change?:

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

neolit123 commented 5 years ago

thanks for moving the PR here @odinuge please have a look at my latest comments.

odinuge commented 5 years ago

Thanks for the feedback @neolit123!

When it comes to the error message I just took the result from the docker info command directly. I guess we can run lowercase on the result inside the validator, but it feels kinda yanky to me.

Originates from here: https://github.com/moby/moby/blob/master/client/errors.go#L18

Here is the output: Screenshot from 2019-11-04 17-21-19

neolit123 commented 5 years ago

ok, i'm surprised that these errors are formatted like so on the side of docker.

neolit123 commented 5 years ago

/lgtm /approve

k8s-ci-robot commented 5 years ago

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: neolit123, odinuge

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubernetes/system-validators/blob/master/OWNERS)~~ [neolit123] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

kubernetes / system-validators

Add check for docker engine liveness #3