AIP-4236 - API Versioning for Version-aware clients #1331
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| id: 4236 | ||||||
| state: reviewing | ||||||
| created: 2024-05-16 | ||||||
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| # Version-aware clients | ||||||
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| APIs can annotate services with [`google.api.api_version`][]. If | ||||||
| `google.api.api_version` is specified, version-aware clients **must** | ||||||
| include the value of `google.api.api_version` in the request to the API. | ||||||
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| ### Expected Generator and Client Library Behavior | ||||||
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| If a service is annotated with `google.api.api_version`, client library | ||||||
| generators **must** include the version in requests sent to the API via | ||||||
| the HTTP Header `X-Goog-Api-Version`. | ||||||
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| Requests which contain the API version, **must** include either an HTTP query | ||||||
| parameter `$apiVersion` or HTTP header `X-Goog-Api-Version`, but a request | ||||||
| **must not** contain both. | ||||||
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| Generated documentation for a given service **may** include the value of | ||||||
| `google.api.api_version`, if it exists in the source protos. | ||||||
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There was a problem hiding this comment. To guide consistent behavior across languages when user attempts to set a user header of the same key, this could be to override an existing version that ships with client library, or attempting to add this header when server does not opt in for this feature.
Suggested change
There was a problem hiding this comment. I'd prefer not to add that, personally. There's only so much you can do to protect users who are determined to do weird things. The chances of someone accidentally setting that header are very slim - and if someone really wants to do so, they can always send a request directly from an HTTP client. We definitely shouldn't provide any way of specifically overriding the header - but I don't think "code that allows headers to be specified" should be modified to try to prevent this. There was a problem hiding this comment.
I agree on this. On the other hand, it also seems valuable to give user usable feedback if we don't intend have this overriden. To add a bit context in Java, we already have some logic trying to resolve conflict between internal header set by defaults and user headers. I am inclined to add logic to throw exception when user attempt to add a header with key "x-goog-api-version" (draft pr). Alternative to this is no change to this existing logic, which will throw exception only when internal header has this key (that's when service has a api version). I don't feel too strongly, but the first one gives a bit more consistent feedback. I realize this is only dealing with an edge case, but also feel that this case is language agnostic, so wanted to check if we want to deal with it consistently across languages. WDTY? There was a problem hiding this comment. I think if Java wants to attempt to stop the user from doing it, that's fine - I don't think it should be in the AIP. |
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| ## Rationale | ||||||
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| The `google.api.api_version` annotation allows services to abide by the schema and | ||||||
| service behavior at the time the API version was deployed. The format of the | ||||||
| API version **must** be treated as opaque by clients. Generators and clients **must not** | ||||||
| interpret the value of `google.api.api_version` beyond the uses mentioned above. | ||||||
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| [`google.api.api_version`]: https://github.com/googleapis/googleapis/blob/master/google/api/client.proto | ||||||
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I've made a bunch of comments re:guidance appearing in this preamble - perhaps that means the preamble needs to be cut down/generalized/removed/converted into guidance. We don't want to repeat ourselves, we don't want to spread guidance out into various places, and we want to be succinct. Adding a
Rationalesection go/aip/8#rationale is probably where you want to be explaining the "why"There was a problem hiding this comment.
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Thanks for reviewing @noahdietz ! Please let me know if this latest version reads better.
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I does! A few more tweaks thanks Tony :)
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Please could you take another look?