JQ

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• JQ Lang Manual

Create JSON

Command

export CLUSTER=MYCLUSTER
export NAMESPACE=MYAPP-NAMESPACE
export POD=POD-XCHDF1
jq --null-input \
        --arg cluster "$CLUSTER" \
        --arg namespace "$NAMESPACE" \
        --arg pod "$POD" \
        '{"cluster": $cluster, "namespace": $namespace, "pod": $pod}'

Result

{
  "cluster": "MYCLUSTER",
  "namespace": "MYAPP-NAMESPACE",
  "pod": "POD-XCHDF1"
}

Flatten JSON

data.json

{
  "kubernetes": {
    "cluster": "MYCLUSTER",
    "namespace": "MYAPP-NAMESPACE",
    "pod": {
      "name": "POD-XCHDF1",
      "replicas": 5
    }
  }
}

Command

cat data.json | jq -r 'paths(scalars) as $path | { ($path | map(tostring) | join("_")): getpath($path) }| to_entries|map("\(.key)=\(.value|tostring)")|.[]'

Result

kubernetes_cluster=MYCLUSTER
kubernetes_namespace=MYAPP-NAMESPACE
kubernetes_pod_name=POD-XCHDF1
kubernetes_pod_replicas=5

Map Key and Values

echo '''
{
  "cluster": "MYCLUSTER",
  "namespace": "MYAPP-NAMESPACE",
  "pod": "POD-XCHDF1"
}
'''|jq -r ' to_entries|map("\(.key)=\(.value|tostring)")|.[]'

Result

cluster=MYCLUSTER
namespace=MYAPP-NAMESPACE
pod=POD-XCHDF1

Test if key is Not Null

Command

$ echo '''
{
  "cluster": "MYCLUSTER",
  "namespace": "MYAPP-NAMESPACE",
  "pod": "POD-XCHDF1"
}
''' | jq -r '{"cluster": (.cluster| .  |= if .==null then "NOK" else "OK" end),"deployment":( .deployment|.  |= if .==null then "NOK" else "OK" end)}'

Result

{
  "cluster": "OK",
  "deployment": "NOK"
}

To CSV

Command

function GEN_JSON() {
    for i in $(seq 1 10)
        do
        export CLUSTER=MYCLUSTER
        export NAMESPACE=MYAPP-NAMESPACE-${i}
        export POD=POD-${i}-XCHDF1
        jq --null-input \
            --arg cluster "$CLUSTER" \
            --arg namespace "$NAMESPACE" \
            --arg pod "$POD" \
            '{"cluster": $cluster, "namespace": $namespace, "pod": $pod}' 
        done
}
$ GEN_JSON | jq -r '.|map(.)|@csv'

Result

"MYCLUSTER","MYAPP-NAMESPACE-1","POD-1-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-2","POD-2-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-3","POD-3-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-4","POD-4-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-5","POD-5-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-6","POD-6-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-7","POD-7-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-8","POD-8-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-9","POD-9-XCHDF1"
"MYCLUSTER","MYAPP-NAMESPACE-10","POD-10-XCHDF1"