This allows for client agent to be run in a more stateless manner where they may be abruptly terminated and not expected to come back. If advertising a per-agent reconnect timeout using the advertise_reconnect_timeout configuration when that agent leaves, other agents will wait only that amount of time for the agent to come back before reaping it.
This has the advantageous side effect of causing servers to deregister the node/services/checks for that agent sooner than if the global reconnect_timeout was used.
In all cases (oss/ent, client/server) this method was returning a value from config. Since the
value is consistent, it doesn't need to be part of the delegate interface.
Previously this happened to be using the method on the Server/Client that was meant to allow the ACLResolver to locally resolve tokens. On Servers that had tokens (primary or secondary dc + token replication) this function would lookup the token from raft and return the ACLIdentity. On clients this was always a noop. We inadvertently used this function instead of creating a new one when we added logging accessor ids for permission denied RPC requests.
With this commit, a new method is used for resolving the identity properly via the ACLResolver which may still resolve locally in the case of being on a server with tokens but also supports remote token resolution.
Also reduce the log level of some version checking messages on the server as they can be pretty noisy during upgrades and really are more for debugging purposes.
Roles are named and can express the same bundle of permissions that can
currently be assigned to a Token (lists of Policies and Service
Identities). The difference with a Role is that it not itself a bearer
token, but just another entity that can be tied to a Token.
This lets an operator potentially curate a set of smaller reusable
Policies and compose them together into reusable Roles, rather than
always exploding that same list of Policies on any Token that needs
similar permissions.
This also refactors the acl replication code to be semi-generic to avoid
3x copypasta.
This PR is almost a complete rewrite of the ACL system within Consul. It brings the features more in line with other HashiCorp products. Obviously there is quite a bit left to do here but most of it is related docs, testing and finishing the last few commands in the CLI. I will update the PR description and check off the todos as I finish them over the next few days/week.
Description
At a high level this PR is mainly to split ACL tokens from Policies and to split the concepts of Authorization from Identities. A lot of this PR is mostly just to support CRUD operations on ACLTokens and ACLPolicies. These in and of themselves are not particularly interesting. The bigger conceptual changes are in how tokens get resolved, how backwards compatibility is handled and the separation of policy from identity which could lead the way to allowing for alternative identity providers.
On the surface and with a new cluster the ACL system will look very similar to that of Nomads. Both have tokens and policies. Both have local tokens. The ACL management APIs for both are very similar. I even ripped off Nomad's ACL bootstrap resetting procedure. There are a few key differences though.
Nomad requires token and policy replication where Consul only requires policy replication with token replication being opt-in. In Consul local tokens only work with token replication being enabled though.
All policies in Nomad are globally applicable. In Consul all policies are stored and replicated globally but can be scoped to a subset of the datacenters. This allows for more granular access management.
Unlike Nomad, Consul has legacy baggage in the form of the original ACL system. The ramifications of this are:
A server running the new system must still support other clients using the legacy system.
A client running the new system must be able to use the legacy RPCs when the servers in its datacenter are running the legacy system.
The primary ACL DC's servers running in legacy mode needs to be a gate that keeps everything else in the entire multi-DC cluster running in legacy mode.
So not only does this PR implement the new ACL system but has a legacy mode built in for when the cluster isn't ready for new ACLs. Also detecting that new ACLs can be used is automatic and requires no configuration on the part of administrators. This process is detailed more in the "Transitioning from Legacy to New ACL Mode" section below.
