return x-backend-storage-policy-index header from object server

[clayg]

object server responses don't include the x-backend-storage-policy-index header:

ubuntu@saio:~$ curl -H 'x-backend-storage-policy-index: 0' http://localhost:6020/sdb2/767/AUTH_test/test/awesome -d test -XPUT -H 'content-length: 4' -H 'x-timestamp: 1476774837.92038' -v
* Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 6020 (#0)
> PUT /sdb2/767/AUTH_test/test/awesome HTTP/1.1
> Host: localhost:6020
> User-Agent: curl/7.47.0
> Accept: */*
> x-backend-storage-policy-index: 0
> content-length: 4
> x-timestamp: 1476774837.92038
> Content-Type: application/x-www-form-urlencoded
>
* upload completely sent off: 4 out of 4 bytes
< HTTP/1.1 201 Created
< Etag: "098f6bcd4621d373cade4e832627b4f6"
< Content-Type: text/html; charset=UTF-8
< Content-Length: 0
< Date: Tue, 18 Oct 2016 07:16:53 GMT
<
* Connection #0 to host localhost left intact

ubuntu@saio:~$ curl -H 'x-backend-storage-policy-index: 0' http://localhost:6020/sdb2/767/AUTH_test/test/awesome -I
HTTP/1.1 200 OK
Content-Length: 5
X-Backend-Timestamp: 1476774837.92036
Content-Type: application/octet-stream
Last-Modified: Tue, 18 Oct 2016 07:13:58 GMT
Etag: "d8e8fca2dc0f896fd7cb4cb0031ba249"
X-Timestamp: 1476774837.92036
X-Backend-Data-Timestamp: 1476774837.92036
X-Backend-Durable-Timestamp: 1476774837.92036
X-Object-Meta-Mtime: 1474654846.291908
Date: Tue, 18 Oct 2016 07:14:33 GMT

... i think they could tho, and it would be helpful when debugging!

It's currently added to the response logging by looking in the request headers:

https://github.com/openstack/swift/blob/a79d8508df493d5744b262e1d1830782e32dbd04/swift/common/utils.py#L505

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/394210

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/394212

[OpenStack Infra (hudson-openstack)]

Change abandoned by Christian Hugo (<email address hidden>) on branch: master
Review: https://review.openstack.org/394210
Reason: Please ignore this change. I made two changes for the same commit.

This one
https://review.openstack.org/#/c/394212/
is right.

[Tim Burke (1-tim-z)]

Clay,

As a client, don't you have to specify the policy? I.e., the

 -H 'x-backend-storage-policy-index: 0'

from your curl example above. And if you don't specify one, it just defaults to 0, right?

I'm not necessarily *opposed*, it just seems a little silly to mirror back a value that's expected to be sent by the client. Maybe sending back the *name* would be more interesting?

[clayg (clay-gerrard)]

well, the client doesn't *have* to send it - and sometimes I forget - so when looking at the response it does seem (to me) like it would be helpful to have it in there (maybe just to remind me I need to set it when I wanna talk to the storage node about a non-legacy policy)

if you use the name instead of the index - i think I'd mostly just have to disambiguate back to index

I think the object server also has the habit of being somewhat liberal in what it will accept:

ubuntu@saio:~$ curl localhost:6010/sdb1/645/AUTH_test/test/test -H 'x-backend-storgae-policy-index: 1' -v
* Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 6010 (#0)
> GET /sdb1/645/AUTH_test/test/test HTTP/1.1
> Host: localhost:6010
> User-Agent: curl/7.47.0
> Accept: */*
> x-backend-storgae-policy-index: 1
>
< HTTP/1.1 200 OK
< Content-Length: 8
< X-Backend-Timestamp: 1483570008.12156
< Content-Type: application/octet-stream
< Last-Modified: Wed, 04 Jan 2017 22:46:49 GMT
< Etag: "70c1db56f301c9e337b0099bd4174b28"
< X-Timestamp: 1483570008.12156
< X-Backend-Data-Timestamp: 1483570008.12156
< X-Backend-Durable-Timestamp: 1483570008.12156
< X-Object-Meta-Mtime: 1477644597.056231
< Date: Wed, 04 Jan 2017 22:49:41 GMT
<
awesome
* Connection #0 to host localhost left intact
ubuntu@saio:~$ tail -n2 /var/log/syslog | head -n1
Jan 4 22:49:41 saio object-6010: 127.0.0.1 - - [04/Jan/2017:22:49:41 +0000] "GET /sdb1/645/AUTH_test/test/test" 200 8 "-" "-" "curl/7.47.0" 0.0014 "-" 7282 -

^ note that response is from 0 - but the log just says - and the client thinks they asked for 1

... so again being explicit about what policy is being responded from (and bonus if we log that) seems helpful for debugging.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/749400

[clayg (clay-gerrard)]

There was some problems in attempting to add this at the proxy layer, it might not be such a great idea.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Tim Burke (<email address hidden>) on branch: master
Review: https://review.opendev.org/749400

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Tim Burke <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/swift/+/693893
Reason: See https://review.opendev.org/c/openstack/swift/+/898783 for a more recent take on the problem

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Tim Burke <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/swift/+/394212
Reason: See https://review.opendev.org/c/openstack/swift/+/693893 for a rolling-upgrade problem, and https://review.opendev.org/c/openstack/swift/+/898783 for a more recent take on the problem