// GetPolicy is used to retrieve a compiled policy object with a TTL. Does not
// support a blocking query.
func (a *ACL) GetPolicy(args *structs.ACLPolicyRequest, reply *structs.ACLPolicy) error {
if done, err := a.srv.forward("ACL.GetPolicy", args, args, reply); done {
return err
}
// Verify we are allowed to serve this request
if a.srv.config.ACLDatacenter != a.srv.config.Datacenter {
return fmt.Errorf(aclDisabled)
}
// Get the policy via the cache
parent, policy, err := a.srv.aclAuthCache.GetACLPolicy(args.ACL)
if err != nil {
return err
}
// Generate an ETag
conf := a.srv.config
etag := fmt.Sprintf("%s:%s", parent, policy.ID)
// Setup the response
reply.ETag = etag
reply.TTL = conf.ACLTTL
a.srv.setQueryMeta(&reply.QueryMeta)
// Only send the policy on an Etag mis-match
if args.ETag != etag {
reply.Parent = parent
reply.Policy = policy
}
return nil
}
// lookupACL is used when we are non-authoritative, and need to resolve an ACL.
func (c *aclCache) lookupACL(id, authDC string) (acl.ACL, error) {
// Check the cache for the ACL.
var cached *aclCacheEntry
raw, ok := c.acls.Get(id)
if ok {
cached = raw.(*aclCacheEntry)
}
// Check for live cache.
if cached != nil && time.Now().Before(cached.Expires) {
metrics.IncrCounter([]string{"consul", "acl", "cache_hit"}, 1)
return cached.ACL, nil
} else {
metrics.IncrCounter([]string{"consul", "acl", "cache_miss"}, 1)
}
// Attempt to refresh the policy from the ACL datacenter via an RPC.
args := structs.ACLPolicyRequest{
Datacenter: authDC,
ACL: id,
}
if cached != nil {
args.ETag = cached.ETag
}
var reply structs.ACLPolicy
err := c.rpc("ACL.GetPolicy", &args, &reply)
if err == nil {
return c.useACLPolicy(id, authDC, cached, &reply)
}
// Check for not-found, which will cause us to bail immediately. For any
// other error we report it in the logs but can continue.
if strings.Contains(err.Error(), aclNotFound) {
return nil, errors.New(aclNotFound)
} else {
c.logger.Printf("[ERR] consul.acl: Failed to get policy from ACL datacenter: %v", err)
}
// TODO (slackpad) - We could do a similar thing *within* the ACL
// datacenter if the leader isn't available. We have a local state
// store of the ACLs, so by populating the local member in this cache,
// it would fall back to the state store if there was a leader loss and
// the extend-cache policy was true. This feels subtle to explain and
// configure, and leader blips should be paved over by cache already, so
// we won't do this for now but should consider for the future. This is
// a lot different than the replication story where you might be cut off
// from the ACL datacenter for an extended period of time and need to
// carry on operating with the full set of ACLs as they were known
// before the partition.
// At this point we might have an expired cache entry and we know that
// there was a problem getting the ACL from the ACL datacenter. If a
// local ACL fault function is registered to query replicated ACL data,
// and the user's policy allows it, we will try locally before we give
// up.
if c.local != nil && c.config.ACLDownPolicy == "extend-cache" {
parent, rules, err := c.local(id)
if err != nil {
// We don't make an exception here for ACLs that aren't
// found locally. It seems more robust to use an expired
// cached entry (if we have one) rather than ignore it
// for the case that replication was a bit behind and
// didn't have the ACL yet.
c.logger.Printf("[DEBUG] consul.acl: Failed to get policy from replicated ACLs: %v", err)
goto ACL_DOWN
}
policy, err := acl.Parse(rules)
if err != nil {
c.logger.Printf("[DEBUG] consul.acl: Failed to parse policy for replicated ACL: %v", err)
goto ACL_DOWN
}
policy.ID = acl.RuleID(rules)
// Fake up an ACL datacenter reply and inject it into the cache.
// Note we use the local TTL here, so this'll be used for that
// amount of time even once the ACL datacenter becomes available.
metrics.IncrCounter([]string{"consul", "acl", "replication_hit"}, 1)
reply.ETag = makeACLETag(parent, policy)
reply.TTL = c.config.ACLTTL
reply.Parent = parent
reply.Policy = policy
return c.useACLPolicy(id, authDC, cached, &reply)
}
ACL_DOWN:
// Unable to refresh, apply the down policy.
switch c.config.ACLDownPolicy {
case "allow":
return acl.AllowAll(), nil
case "extend-cache":
if cached != nil {
return cached.ACL, nil
}
fallthrough
default:
return acl.DenyAll(), nil
}
}