Pass variable within json payload in shell script

Question

In the following scenario, which is the way to pass ${MY_ENV_VAR} in the payload?

I will have to escape:

a) the single quotes of the payload

b) the double quotes of the value of the text json field

I need ${MY_ENV_VAR) to be interpolated of course.

#!/bin/bash

COMMAND=${MY_ENV_VAR}    

curl -X POST --data-urlencode 'payload={"channel": "#alerts", "username": "k8s-cronjobs-bot", "text": "Command ${MY_ENV_VAR} run with success", "icon_emoji": ":ghost:"}' ${SLACK_WEBHOOK}

Solution 1

With jq:

$ payload='{"channel": "#alerts", "username": "k8s-cronjobs-bot", "text": "", "icon_emoji": ":ghost:"}'
$ MY_ENV_VAR='"foo"'
$ echo "$payload" | jq --arg cmd "$MY_ENV_VAR" '.text = "Command " + $cmd + " run with success"'
{
  "channel": "#alerts",
  "username": "k8s-cronjobs-bot",
  "text": "Command \"foo\" run with success",
  "icon_emoji": ":ghost:"
}

So your script would look like:

#!/bin/bash

COMMAND=${MY_ENV_VAR}    
payload='{"channel": "#alerts", "username": "k8s-cronjobs-bot", "text": "", "icon_emoji": ":ghost:"}'
payload=$(echo "$payload" | jq -r --arg cmd "$COMMAND" '.text = "Command " + $cmd + " run with success"')
curl -X POST --data-urlencode "payload=$payload"  "${SLACK_WEBHOOK}"

Solution 2

Or, use printf to help with the mix of quotes:

printf -v payload '{"channel": "#alerts", "username": "k8s-cronjobs-bot", "text": "Command %s run with success", "icon_emoji": ":ghost:"}' "$MY_ENV_VAR"
curl -X POST --data-urlencode "payload=$payload" "$SLACK_WEBHOOK"

Comments

[pkaramol]

You are right, I fixed this

[muru]

Can you use the jq command?

[pkaramol]

Any suggestions how to go about it? You can post it as answer so that I also accept it