How can get Google to index a URL with a canonical tag?

We have the URL routes with the schema: /ads/:city. The objective is to get URLs that use this route indexed in Google:

  • /ads/joinville
  • /ads/lages
  • /ads/florianopolis

Today, just /ads/lages is indexing as a canonical even though with rel canonical tag.

The canonical tag is: <link rel="canonical" href="" />

How we can get Google to index all these URLs?