Support checkLimit for multiple pages

[timoreimann]

This change implements paging uses the Meta.Total field from the godo response when listing volumes for account limit checking, thereby supporting limits beyond the size of a single page.

We also refactor checkLimits to not return gRPC codes but leave that to the calling function. This also allows us to distinguish between true errors and limit violations, and better handle each case.

[adamwg]

We shouldn't need to iterate over all the pages to figure out how many volumes/snaps the user has. In the Response object, we get the number of total pages, and we can control the number of volumes per page. If we set PerPage to 1, we can make a single API call and use the total number of pages returned as the volume count.

[adamwg]

Also wanted to note: the volumes API in particular also returns a meta field in the response, which explicitly says the total number of volumes the account has:

  "meta": {
    "total": 8316
  },

I think godo ignores this, but we could integrate it into godo and leverage it here rather than relying on the pagination data.

[jcodybaker]

Reviewed. No concerns other than those already raised by AWG.

[timoreimann]

@adamwg I like the idea to use the page count in order to determine the number of volumes until the meta field is available in godo.

Looking more closely at things, however, it looks like the number of pages isn't directly available in godo but only through the Last reference which seems to be a URL. The functionality godo uses to parse page numbers from the links seems non-exported.

I'd rather not implement / copy the parsing logic in(to) our repo, which makes an upstream contribution to godo exposing the meta field more desirable to me right now. But please let me know if I missed something.

(FWIW, there's no super urge to get this PR in, so we can wait a bit for any godo PR to get merged and released.)

[timoreimann]

Submitted digitalocean/godo#286.

[timoreimann]

my godo contribution was merged and released. This PR is now using godo 1.29.0 and leverages the Meta.Total field.

@adamwg @jcodybaker would you mind taking a look again when you have a minute?

[adamwg]

lgtm.

[jcodybaker]

LGTM. Have you verified that list volumes honors and correctly implements the per-page=1 option?

[timoreimann]

@jcodybaker

Have you verified that list volumes honors and correctly implements the per-page=1 option?

That does seem to be the case:

$ curl -sfX GET -H "Content-Type: application/json" -H "Authorization: Bearer <REDACTED>" "https://api.digitalocean.com/v2/volumes?per_page=1" | jq '. | {meta: .meta, numVolumes: .volumes | length}'

{
  "meta": {
    "total": 14
  },
  "numVolumes": 1
}

[jcodybaker]

Nice