Use endpoint as default connection option (ADR-119)

[surminus]

This implements ADR-119[1], which specifies the client connection options to update requests to the endpoints implemented as part of ADR-042[2].

The endpoint may be one of the following:

a routing policy name (such as main) a nonprod routing policy name (such as nonprod:sandbox) a FQDN such as foo.example.com The endpoint option is not valid with any of environment, restHost or realtimeHost, but we still intend to support the legacy options.

If the client has been configured to use any of these legacy options, then they should continue to work in the same way, using the same primary and fallback hostnames.

If the client has not been explicitly configured, then the hostnames will change to the new ably.net domain when the package is upgraded.

Notes on implementation

As per previous guidance, I have not updated tests to use the endpoint client option, but since the hostnames are changing, then the assertions and default environment must be updated (from sandbox to nonprod:sandbox).

I have not added any explicit tests for the endpoint client option, but I can do this if we think it's necessary, although using environment is essentially the same as using endpoint.

See related Go and Ruby PRs:

• https://github.com/ably/ably-go/pull/679
• https://github.com/ably/ably-ruby/pull/441

[1] https://ably.atlassian.net/wiki/spaces/ENG/pages/3428810778/ADR-119+ClientOptions+for+new+DNS+structure [2] https://ably.atlassian.net/wiki/spaces/ENG/pages/1791754276/ADR-042+DNS+Restructure

Summary by CodeRabbit

Summary by CodeRabbit

• New Features

  • Introduced an “endpoint” parameter for more reliable connection configurations, replacing previous environment settings.
  • Updated service endpoints ensure production connections default to the new primary host while sandbox (non-production) environments use revised host URLs.
  • Added support for specifying routing policies or fully qualified domain names via the new endpoint parameter in client initialization.

• Bug Fixes

  • Adjusted tests to align with new host configurations, ensuring accurate assertions for both production and sandbox environments.

• Refactor

  • Streamlined configuration and validation to minimize conflicting inputs and clarify host selection, enhancing overall connectivity.
  • Deprecated older parameters to improve clarity in connection settings.

[coderabbitai[bot]]

Walkthrough

The pull request modifies the host configuration logic in the Ably SDK. In ably/transport/defaults.py, the Defaults class replaces static fallback hosts and hostnames with dynamic generation based on an endpoint string. The Options class in ably/types/options.py enforces mutual exclusivity between endpoint and environment parameters and uses the new hostname resolution methods. Test files are updated to reflect new host URLs and environment naming conventions. The AblyRest and AblyRealtime classes add an endpoint parameter and mark rest_host and environment as deprecated.

Changes

File(s)	Change Summary
ably/transport/defaults.py	Refactored Defaults class: removed static fallback hosts and hostnames; replaced environment with endpoint attribute; added static methods get_hostname and get_fallback_hosts for dynamic host generation based on endpoint string.
ably/types/options.py	Updated Options constructor to add endpoint parameter; enforce mutual exclusivity with environment, rest_host, and realtime_host; replaced environment property with endpoint; updated host resolution logic to use Defaults.get_hostname and Defaults.get_fallback_hosts.
test/ably/rest/restinit_test.py, test/ably/rest/restpaginatedresult_test.py, test/ably/rest/restrequest_test.py, test/ably/testapp.py	Updated test host URLs and environment identifiers to match new endpoint-based host naming conventions, including changes from "production" to "main" and "sandbox" to "nonprod:sandbox".
ably/realtime/realtime.py, ably/rest/rest.py	Added new endpoint parameter to AblyRealtime and AblyRest constructors; marked existing realtime_host, rest_host, and environment parameters as deprecated in documentation.
test/unit/options_test.py	Added new test suite for Options class validating mutual exclusivity of parameters, default and custom endpoint hostnames, fallback hosts, and handling of FQDN and IP addresses as endpoints.

Sequence Diagram(s)

sequenceDiagram
    participant Client
    participant Options
    participant Defaults
    Client->>Options: Instantiate with endpoint (or environment)
    Options->>Options: Validate mutual exclusivity (raise error if both present)
    Options->>Defaults: get_hostname(endpoint)
    Defaults-->>Options: Return primary hostname
    Options->>Defaults: get_fallback_hosts(endpoint)
    Defaults-->>Options: Return fallback hosts
    Options-->>Client: Return configured Options instance

Poem

I'm a bunny, hopping with glee,
New endpoints shine for all to see.
I nibble on bugs with whiskers twitch,
As fallback hosts appear without a glitch.
With every hop and joyful cheer,
CodeRabbit sings: "Update, my dear!"
(_/) 🥕 Happy coding!

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[surminus]

Great, thank you for the review.

Given the impact of this changes, I would also like to see some endpoint tests (could be simple unit tests) to check that providing a new endpoint option results in the expected rest host, realtime host and fallback hosts used.

I will add these tests.

Should we do the same here, or can create a separate ticket for it? Don't know if there was an explicit decision to deprecate those.

I can do that as part of this PR, that's fine. I'll also need to update my ably-js and ably-ruby PRs.

[VeskeR]

Just a heads up:

test/ably/rest/resthttp_test.py::TestRestHttp::test_request_headers - test consistently fails after changes, should investigate

This is not related to this PR, fixed in https://github.com/ably/ably-python/pull/593. You can ignore test_request_headers test failures for the time being

[surminus]

@VeskeR @sacOO7 thanks for reviews, I've updated this PR with a fixup that adds some (very basic) tests, ensures client combinations are incompatible, and addresses code comments.

[lawrence-forooghian]

@surminus as discussed on Slack, please could you make sure that this PR implements / tests the updates to REC1b2 from https://github.com/ably/specification/pull/302? Thanks!

[surminus]

@lawrence-forooghian updated