Vultr CLI and JSON output

June 2, 2022 - 2 minutes read - 411 words

I’ve begun exploring Vultr after the company announced a managed Kubernetes offering Vultr Kubernetes Engine (VKE).

In my brief experience, it’s a decent platform and its CLI vultr-cli is mostly (!) good. The CLI has a limitation in that command output is text formatted and this makes it challenging to parse the output when scripting.

NOTE The Vultr developers have a branch rewrite that includes a solution to this problem.

Example

ID              12345678-90ab-cdef-1234-567890abcdef
LABEL           test
DATE CREATED    2022-01-01T00:00:00+00:00
CLUSTER SUBNET  255.255.255.255/16
SERVICE SUBNET  255.255.255.255/12
IP              255.255.255.255
ENDPOINT        12345678-90ab-cdef-1234-567890abcdef.vultr-k8s.com
VERSION         v1.23.5+3
REGION          mars
STATUS          pending
 
NODE POOLS
ID              12345678-90ab-cdef-1234-567890abcdef
DATE CREATED    2022-01-01T00:00:00+00:00
DATE UPDATED    2022-01-01T00:00:00+00:00
LABEL           nodepool
TAG             foo
PLAN            vc2-1c-2gb
STATUS          pending
NODE QUANTITY   1
AUTO SCALER     false
MIN NODES       1
MAX NODES       1
 
NODES
ID                                      DATE CREATED                    LABEL                   STATUS
12345678-

Until that’s available, I’m lazy writing very simple bash scripts to parse vultr-cli command output as JSON. The repo is vultr-cli-format.

Ideally, the scripts would invoke the underlying vultr-cli command in order to be able to ‘determine’ which command was being invoked and apply the correct formatting. But, for simplicity, the user must choose the correct command.

NOTE I’m considering restructuring the scripts so that they follow the vultr-cli command format, i.e.
vultr-cli kubernetes get |\
./ vultr-cli-output kubernetes get

There are multiple issues with this approach but being able to systematise converting vultr-cli commands into a more structured form so that the output may be used in scripting, outweighs many of these.

Issues

vultr-cli command output may change
Repeated sections in the command output (e.g. NODE POOLS and NODES in the above example) are not converted
Table-oriented output (e.g. NODES in the above example) are not being converted.
Using read, output field names that are space separated (e.g. CLUSTER SUBNET) require extra care
Likely others

Benefit

FORMAT="/path/to/script"

# Get latest Kubernetes version
VERSION=$(\
vultr-cli kubernetes versions \
| ${FORMAT}/k8s_version.sh \
| jq -r .version)

# Create a cluster and return its ID
ID=$(\
vultr-cli kubernetes create \
--label=${LABEL} \
--region=${REGION} \
--version=${VERSION} \
--node-pools=quantity:1,plan:vc2-1c-2gb,label:nodepool,tag:pool \
| ${FORMAT}/k8s.sh \
| jq -r .id)

# Wait until the cluster is active
until [ "active" = $(\
vultr-cli kubernetes get ${ID} \
| ${FORMAT}/k8s.sh \
| jq -r .status) ]
do
sleep 15s
done

# Create temporarily VKE config
local CONFIG="${PWD}/tmp/vke.$(date +%y%m%d).yaml"
vultr-cli kubernetes config ${ID} \
| base64 --decode > ${CONFIG}

# Create a namespace
kubectl create namespace ${NAMESPACE} \
--kubeconfig=${CONFIG}

# Deploy something
kubectl apply --filename=${DEPLOYMENT} \
--namespace=${NAMESPACE} \
--kubeconfig=${CONFIG}