Update json file using jq in bash shell

jq_update.sh

#!/bin/sh

updateAllowedHosts() {
    if [ -n "$ECS_CONTAINER_METADATA_FILE" ]; then
        echo "getting ecs container metadata file '$ECS_CONTAINER_METADATA_FILE'"

        local appSettings='appsettings.json'
        local currentHosts=

        # check if env appsettings exist
        if [ -n $ASPNETCORE_ENVIRONMENT ] && [ -f "appsettings.${ASPNETCORE_ENVIRONMENT}.json" ]; then
            echo "found env specific appsettings for '${ASPNETCORE_ENVIRONMENT}'"
            appSettings="appsettings.${ASPNETCORE_ENVIRONMENT}.json"
        fi
        
        local hostIp=$(cat $ECS_CONTAINER_METADATA_FILE | jq -r 'select(.HostPrivateIPv4Address != null) | .HostPrivateIPv4Address')

        if [ -n "${hostIp}" ]; then
            currentHosts=$(cat "${appSettings}" | jq -r 'select(.AllowedHosts != null) | .AllowedHosts')
            
            local allowedHosts=
            [ -n "${currentHosts}" ] && allowedHosts="${currentHosts};${hostIp}" || allowedHosts=$hostIp
            
            echo "adding allowed hosts '${allowedHosts}'"
            $(cat $appSettings | jq -e ".AllowedHosts = \"${allowedHosts}\""  > "${appSettings}.tmp" && cp "${appSettings}.tmp" $appSettings)
        else
            echo 'no ecs host ip was found!'
        fi
    fi
}