Bash 使用脚本获取转义的变量键值

Question

I want to use jq to get value's out of a the Traefik API service. The output of the service looks like this:

{
  "loadBalancer": {
    "servers": [
      {
        "url": "http://172.18.0.19:3000"
      },
      {
        "url": "http://172.18.0.17:3000"
      },
      {
        "url": "http://172.20.0.3:3000"
      }
    ],
    "healthCheck": {
      "path": "/health",
      "interval": "10s",
      "timeout": "10s",
      "followRedirects": true
    },
    "passHostHeader": true
  },
  "status": "enabled",
  "serverStatus": {
    "http://172.18.0.17:3000": "UP",
    "http://172.18.0.19:3000": "UP",
    "http://172.20.0.3:3000": "DOWN"
  },
  "provider": "docker",
  "type": "loadbalancer"
}

I want to get the value of the serverStatus dynamically. First assigning a variable with the correct IP address from docker inspect. I'm using curl with jq to check if the container is being serviced.

The problem is when getting it with a variable I cannot seem to escape the special characters in the url key. Nothing is returned .

This is the command I use is:

TRAEFIK_URL="http://someurl.com/"
TRAEFIK_URL="'Authorization: Basic hashkey"
NEW_IPADDRESS=$(docker container inspect some_container_name | jq -r .[].NetworkSettings.Networks.proxy.IPAddress)
NEW_ENV_URL="http://${NEW_IPADDRESS}:3000"

curl --location --request GET "$TRAEFIK_URL" --header "$TRAEFIK_AUTH_HEADER" | jq -r '.serverStatus["${NEW_ENV_URL}"]'

I've tried using this command and some other obvious options but all didn't work.

jq -r .serverStatus[$NEW_ENV_URL]

I do get the correct value when I'm not using a variable to get the status using:

 jq -r '.serverStatus["http://172.18.0.17:3000"]'

Any help is welcome.

Answer 1

Use the option --arg to pass arguments to jq .

jq --arg url http://172.18.0.17:3000 -r '.serverStatus[$url]'

Always use this option to avoid security problems by injections.

Answer 2

One of the preferred ways to pass specific environment variables into jq is using the --arg command-line option; in your case:

jq -r --arg url "${NEW_ENV_URL}"  '.serverStatus[$url]'