There is no possibility to operate with old cluster after upgrade master to 7.0 and https only enabled

[Tatyanka]

Steps to reproduce:
1. Deploy master node with official Mirantis 6.1 release
2. Create simple cluster : 1 controller + 1 compute +1 cinder with Centos, run ostf
3. upgrade master node to 7.0
4. enable https only mode on master node
    Open ssh to the master
Edit /etc/fuel/astute.yaml file
Add the following to the end of the file:

"SSL":
      "force_https": "true"
 Restart nginx container
5. Try to add the nodes to 6.1 running cluster (current nodes will mark as offline in nailgun)
6. ssh on one of the node and run command yum update (nailgun -agent with https support should come, but unexpectedly it is not )
7. Try to get nailgun agent that support https from master node repo (7.0) and install it
8. Edit nailgun -config change http to https and change the port)

Try to start agent

Current result:I, [2015-09-18T12:00:12.804629 #21844] INFO -- : Trying to load agent config /etc/nailgun-agent/config.yaml
I, [2015-09-18T12:00:12.804923 #21844] INFO -- : Obtained service url from config file: 'https://10.109.0.2:8443/api'
/usr/bin/nailgun-agent:143:in `initialize': undefined method `[]' for nil:NilClass (NoMethodError)
 from /usr/bin/nailgun-agent:730:in `new'
 from /usr/bin/nailgun-agent:730

So the main problems that looks like critical:
1. There is no nailgun agent with https support in 6.1 update mirrors
2. There is no any mention about needed changes in config and how exactly to update package in official documentation
3. current nailgun agent from 7.0 repository nailgun-agent-7.0.0-136.1.gitd702795.noarch
failed to start with mentioned above error

{"build_id": "289", "build_number": "289", "release_versions": {"2015.1.0-7.0": {"VERSION": {"build_id": "289", "build_number": "289", "api": "1.0", "fuel-library_sha": "08ae959d38bbe56309190a875289aec618971216", "nailgun_sha": "16a39d40120dd4257698795f12de4ae8200b1778", "feature_groups": ["mirantis"], "fuel-nailgun-agent_sha": "d7027952870a35db8dc52f185bb1158cdd3d1ebd", "openstack_version": "2015.1.0-7.0", "fuel-agent_sha": "082a47bf014002e515001be05f99040437281a2d", "production": "docker", "python-fuelclient_sha": "2864459e27b0510a0f7aedac6cdf27901ef5c481", "astute_sha": "a717657232721a7fafc67ff5e1c696c9dbeb0b95", "fuel-ostf_sha": "1f08e6e71021179b9881a824d9c999957fcc7045", "release": "7.0", "fuelmain_sha": "6b83d6a6a75bf7bca3177fcf63b2eebbf1ad0a85"}}, "2014.2.2-6.1": {"VERSION": {"build_id": "2015-06-19_13-02-31", "build_number": "525", "api": "1.0", "fuel-library_sha": "2e7a08ad9792c700ebf08ce87f4867df36aa9fab", "nailgun_sha": "dbd54158812033dd8cfd7e60c3f6650f18013a37", "feature_groups": ["mirantis"], "openstack_version": "2014.2.2-6.1", "production": "docker", "python-fuelclient_sha": "4fc55db0265bbf39c369df398b9dc7d6469ba13b", "astute_sha": "1ea8017fe8889413706d543a5b9f557f5414beae", "fuel-ostf_sha": "8fefcf7c4649370f00847cc309c24f0b62de718d", "release": "6.1", "fuelmain_sha": "a3998372183468f56019c8ce21aa8bb81fee0c2f"}}}, "auth_required": true, "api": "1.0", "fuel-library_sha": "08ae959d38bbe56309190a875289aec618971216", "nailgun_sha": "16a39d40120dd4257698795f12de4ae8200b1778", "feature_groups": ["mirantis"], "fuel-nailgun-agent_sha": "d7027952870a35db8dc52f185bb1158cdd3d1ebd", "openstack_version": "2015.1.0-7.0", "fuel-agent_sha": "082a47bf014002e515001be05f99040437281a2d", "production": "docker", "python-fuelclient_sha": "2864459e27b0510a0f7aedac6cdf27901ef5c481", "astute_sha": "a717657232721a7fafc67ff5e1c696c9dbeb0b95", "fuel-ostf_sha": "1f08e6e71021179b9881a824d9c999957fcc7045", "release": "7.0", "fuelmain_sha": "6b83d6a6a75bf7bca3177fcf63b2eebbf1ad0a85"}

[Dmitry Pyzhov (dpyzhov)]

6.1 environments do not support https connections to the master node. And manual update of fuel-nailgun-agent on 6.1 environment to 7.0 version will not work. So workaround here is to not enforce SSL connections if you have environments that don't support it. We should add a release note about it. Changing priority to High.

[Ihor Kalnytskyi (ikalnytskyi)]

Yep. One more thing - we can make a backport of https://review.openstack.org/#/c/209170/3 to stable/6.1 and distribute updated nailgun-agent to 6.1 envs through MU channel. In this case, user will have ability to support this case.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/227235

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/227235
Committed: https://git.openstack.org/cgit/stackforge/fuel-docs/commit/?id=2f60cf9abef07462072329d40d1559b2752b2d30
Submitter: Jenkins
Branch: master

commit 2f60cf9abef07462072329d40d1559b2752b2d30
Author: evkonstantinov <email address hidden>
Date: Thu Sep 24 14:15:24 2015 +0300

    Add HTTPS support for 6.1 env issue to relnotes 7.0

    Change-Id: I8f68835d5d7a9accc89fe3944d059d4321104911
    Related-Bug:#1497271

[Alexey Stupnikov (astupnikov)]

We no longer support MOS5.1, MOS6.0, MOS6.1
We deliver only Critical/Security fixes to MOS7.0, MOS8.0.
We deliver only High/Critical/Security fixes to MOS9.2.