JQ example of merging files and replacing with environment variables values

jq example to merge files and to replace some placeholders

        # Read base json file
        if [ -f "base.json" ]; then
          # Read the file into a variable
          json_base=$(jq '.' base.json)
        else
          printf "Base json file does not exist and is required"
          exit 1;
        fi
        
        # Read variable specific json file and merge it into base
        if [ -f "base.${{ env.VARIABLE }}.json" ]; then
          # Read the file and merge it into the base
          printf "Merging base.${{ env.VARIABLE }}.json into base Json\n"
          json_base=$(jq -s '.[0] * .[1]' <(echo $json_base) base.${{ env.VARIABLE }}.json)
        else
          printf "Configuration for base.${{ env.VARIABLE }} does not exist but isn't required\n"
        fi
        
        # Use jq to add environment variable to replace placeholder values in the base json and create the final form and save the file
        # this will look for a string $VARIABLE2 anywhere in the json and replace it with the environment value of VARIABLE2
        printf "Current base json:\n$json_base\n";
        printf "Replacing placeholders with environment variables\n";
        jq --arg VARIABLE2 "$VARIABLE2" \
        'walk(if type == "string" then
          gsub("\\$VARIABLE2"; $VARIABLE2) |
        else . end)' <(echo -n $json_base) > json_finale.json;