Space separated values; how to provide a value containing a space

I'm creating a bash script to provision multiple Azure resources via the Azure CLI. So far so good, however I'm having a problem tagging resources.

My goal is to store multiple tags in a variable and provide that variable to the --tags option of several az commands in the script. The problem however is that a space in the value will be interpreted as a new key.

If we take for example the command az group update (which will update a resource group) the docs state the following about the --tags option:

--tags Space-separated tags in 'key[=value]' format. Use "" to clear existing tags.

When a value (or key) contains spaces it must be enclosed in quotes. So when we provide the key-value pairs directly to the command including a value with spaces, like in the following example, the result will be as expected:

az group update --tags owner="FirstName LastName" application=coolapp --name resource-group-name

The result will be that two tags have been added to the resource group:

{
  "id": "/subscriptions/1e42c44c-bc55-4b8a-b35e-de1dfbcfe481/resourceGroups/resource-group-name",
  "location": "westeurope",
  "managedBy": null,
  "name": "resource-group-name",
  "properties": {
    "provisioningState": "Succeeded"
  },
  "tags": {
    "application": "coolapp",
    "owner": "FirstName LastName"
  }
}

However, when we store the same value we used in the previous step in a variable the problem occurs.

tag='owner="FirstName LastName" application=coolapp'

I use echo $tag to validate that the variable contains exactly the same value as we provided in the previous example to the --tags option:

owner="FirstName LastName" application=coolapp

But when we provide this tag variable to the tags option of the command as shown in the next line:

az group update --tags $tag --name resource-group-name

The result will be three tags instead of the expected two:

{
  "id": "/subscriptions/1e42c44c-bc55-4b8a-b35e-de1dfbcfe481/resourceGroups/resource-group-name",
  "location": "westeurope",
  "managedBy": null,
  "name": "resource-group-name",
  "properties": {
    "provisioningState": "Succeeded"
  },
  "tags": {
    "LastName\"": "",
    "application": "coolapp",
    "owner": "\"FirstName"
  }
}

I've already tried defining the variable in the following ways, but no luck so far:

tag="owner=FirstName LastName application=coolapp"
tag=owner="Firstname Lastname" application=cool-name
tag='`owner="Firstname Lastname" application=cool-name`'

I even tried defining the variable as an array and providing it to the command as shown on the next line, but also that didn't provide the correct result:

tag=(owner="Firstname Lastname" application=cool-name)

az group update --tags ${tag[*]}--name resource-group-name

I also tried putting quotes around the variable in the command, as was suggested by @socowi, but this leads to the following incorrect result of one tag instead of two:

az group update --tags "$tag" --name resource-group-name

{
  "id": "/subscriptions/1e42c44c-bc55-4b8a-b35e-de1dfbcfe481/resourceGroups/resource-group-name",
  "location": "westeurope",
  "managedBy": null,
  "name": "resource-group-name",
  "properties": {
    "provisioningState": "Succeeded"
  },
  "tags": {
    "owner": "Firstname Lastname application=cool-name"
  }
}

Does anybody know how to solve this?

Define your tags as

tags=("owner=Firstname Lastname" "application=cool-name")

then use

--tags "${tags[@]}"