API versioning

[iilyak]

Overview

This PR implements a draft of proposal

Testing recommendations

Running make check should be sufficient. You might need to comment out the following line because elixir tests are failing for prototype/fdb-layer.

You also can run API version related test suite alone as follows exunit tests=src/chttpd/test/exunit/api_version_test.exs

The manual testing can be done using the following:

curl -u adm:pass "http://127.0.0.1:15984/_all_dbs"
["_users","test"]
curl -u adm:pass "http://127.0.0.1:15984/_all_dbs" -H "X-Couch-API: 1"
["_users","test"]
curl -u adm:pass "http://127.0.0.1:15984/_v1/_all_dbs"
["_users","test"]
curl -u adm:pass "http://127.0.0.1:15984/_all_dbs" -H "Accept: application/couchdb; _v=1,application/json"
["_users","test"]
curl -u adm:pass "http://127.0.0.1:15984/_all_dbs" -H "X-Couch-API: 2"
{"bookmark":"123456","items":["foo","bar","baz"]}
curl -u adm:pass "http://127.0.0.1:15984/_v2/_all_dbs"
{"bookmark":"123456","items":["foo","bar","baz"]}
curl -u adm:pass "http://127.0.0.1:15984/_all_dbs" -H "Accept: application/couchdb; _v=2,application/json"
{"bookmark":"123456","items":["foo","bar","baz"]}

Related Issues or Pull Requests

Checklist

• [x] Code is written and works correctly
• [x] Changes are covered by tests
• [ ] Any new configurable parameters are documented in rel/overlay/etc/default.ini
• [ ] A PR for documentation changes has been made in https://github.com/apache/couchdb-documentation

[iilyak]

I refactored PR to parse Version earlier and added tests

[bessbd]

Do we want this in 3.2 or do we intend to add the version option in >3.x onwards?

[iilyak]

There were no consensus https://lists.apache.org/thread.html/rcc742c0fdca0363bb338b54526045720868597ea35ee6842aef174e0%40%3Cdev.couchdb.apache.org%3E.

However Adam started new discussion about it recently https://github.com/apache/couchdb/blob/main/src/chttpd/src/chttpd_httpd_handlers.erl#L62:L495