Right now every controller rotates fernet keys. This is nice because
should any controller die, we know the remaining ones will rotate the
keys. However, we are currently over-rotating the keys.
When we over rotate keys, we get logs like this:
This is not a recognized Fernet token <token> TokenNotFound
Most clients can recover and get a new token, but some clients (like
Nova passing tokens to other services) can't do that because it doesn't
have the password to regenerate a new token.
With three controllers, in crontab in keystone-fernet we see the once a day
correctly staggered across the three controllers:
ssh ctrl1 sudo cat /etc/kolla/keystone-fernet/crontab
0 0 * * * /usr/bin/fernet-rotate.sh
ssh ctrl2 sudo cat /etc/kolla/keystone-fernet/crontab
0 8 * * * /usr/bin/fernet-rotate.sh
ssh ctrl3 sudo cat /etc/kolla/keystone-fernet/crontab
0 16 * * * /usr/bin/fernet-rotate.sh
Currently with three controllers we have this keystone config:
[token]
expiration = 86400 (although, keystone default is one hour)
allow_expired_window = 172800 (this is the keystone default)
[fernet_tokens]
max_active_keys = 4
Currently, kolla-ansible configures key rotation according to the following:
rotation_interval = token_expiration / num_hosts
This means we rotate keys more quickly the more hosts we have, which doesn't
make much sense.
Keystone docs state:
max_active_keys =
((token_expiration + allow_expired_window) / rotation_interval) + 2
For details see:
https://docs.openstack.org/keystone/stein/admin/fernet-token-faq.html
Rotation is based on pushing out a staging key, so should any server
start using that key, other servers will consider that valid. Then each
server in turn starts using the staging key, each in term demoting the
existing primary key to a secondary key. Eventually you prune the
secondary keys when there is no token in the wild that would need to be
decrypted using that key. So this all makes sense.
This change adds new variables for fernet_token_allow_expired_window and
fernet_key_rotation_interval, so that we can correctly calculate the
correct number of active keys. We now set the default rotation interval
so as to minimise the number of active keys to 3 - one primary, one
secondary, one buffer.
This change also fixes the fernet cron job generator, which was broken
in the following cases:
* requesting an interval of more than 1 day resulted in no jobs
* requesting an interval of more than 60 minutes, unless an exact
multiple of 60 minutes, resulted in no jobs
It should now be possible to request any interval up to a week divided
by the number of hosts.
Change-Id: I10c82dc5f83653beb60ddb86d558c5602153341a
Closes-Bug: #1809469
There is inconsistent use of either `/usr/bin/python` or
`/usr/bin/env python`. This makes for unexpected results when a
user might be using a virtualenv.
Change-Id: Ibb030f920a8869f9113ade70b66a921cc815060d
This addresses the ansible aspects of fernet key bootstrapping as
well as distributed key rotation.
- Bootstrapping is handled in the same way as keystone bootstrap.
- A new keystone-fernet and keystone-ssh container is created to allow
the nodes to communicate with each other (taken from nova-ssh).
- The keystone-fernet is a keystone container with crontab installed.
This will handle key rotations through keystone-manage and trigger
an rsync to push new tokens to other nodes.
- Key rotation is setup to be balanced across the keystone nodes using
a round-robbin style. This ensures that any node failures will not
stop the keys from rotating. This is configured by a desired token
expiration time which then determines the cron scheduling for each
node as well as the number of fernet tokens in rotation.
- Ability for recovered node to resync with the cluster. When a node
starts it will run sanity checks to ensure that its fernet tokens
are not stale. If they are it will rsync with other nodes to ensure
its tokens are up to date.
The Docker component is implemented in:
https://review.openstack.org/#/c/349366
Change-Id: I15052c25a1d1149d364236f10ced2e2346119738
Implements: blueprint keystone-fernet-token