[FIXED] How to replace values in a JSON dictionary with their respective shell variables in jq?

Issue

I have the following JSON structure:

{
  "host1": "$PROJECT1",
  "host2": "$PROJECT2",
  "host3" : "xyz",
  "host4" : "$PROJECT4"
}

And the following environment variables in the shell:

PROJECT1="randomtext1"
PROJECT2="randomtext2"
PROJECT4="randomtext3"

I want to check the values for each key, if they have a "$" character in them, replace them with their respective environment variable(which is already present in the shell) so that my JSON template is rendered with the correct environment variables.

I can use the --args option of jq but there are quite a lot of variables in my actual JSON template that I want to render.

I have been trying the following:

jq 'with_entries(.values as v | env.$v)

Basically making each value as a variable, then updating its value with the variable from the env object but seems like I am missing out on some understanding. Is there a straightforward way of doing this?

EDIT

Thanks to the answers on this question, I was able to achieve my larger goal for a part of which this question was asked

• iterating over each value in an object,
• checking its value,
  • if it's a string and starts with the character "$"
    • use the value to update it with an environment variable of the same name .
  • if it's an array
    • use the value to retrieve an environment variable of the same name
    • split the string with "," as delimiter, which returns an array of strings
    • Update the value with the array of strings

         
jq 'with_entries(.value |= (if (type=="array") then (env[.[0][1:]] | split(",")) elif (type=="string" and startswith("$")) then (env[.[1:]]) else  . end))'

Solution

You need to export the Bash variables to be seen by jq:

export PROJECT1="randomtext1"
export PROJECT2="randomtext2"
export PROJECT4="randomtext3"

Then you can go with:

jq -n 'with_entries((.value | select(startswith("$"))) |= env[.[1:]])'

and get:

{
  "host1": "randomtext1",
  "host2": "randomtext2",
  "host3": "xyz",
  "host4": "randomtext3"
}

Answered By - pmf

Answer Checked By - Katrina (PHPFixing Volunteer)