Memcached in Kolla-Kubernetes

Overview

`Memcached <https://memcached.org/>_ is the default persistant cache for a `Kolla-Kubernetes cluster.

Preparation and Deployment

Memcached is self-sufficient, thus it’s one of the first things you want to start while installing.

Memcache does not require bootstrapping. To create the Replication Controller that will keep Memcached running:

kolla-kubernetes start memcached

Verify Operation

To find the IP address of the kubernetes service so you can test for functionality on a machine inside of the Kubernetes cluster (e.g. running Kube-proxy) but not running as a container:

kubectl get svc memcached

Once you know the IP address and port, you can check to see if memcached is responding to requests by replacing <ADDRESS> with the address of the memcached service:

echo "stats settings" | nc <ADDRESS> 11211

You should see output looking like this::

STAT maxbytes 67108864
STAT maxconns 1024
STAT tcpport 11211
STAT udpport 11211
STAT inter 0.0.0.0
STAT verbosity 2
STAT oldest 0
STAT evictions on
STAT domain_socket NULL
STAT umask 700
STAT growth_factor 1.25
STAT chunk_size 48
STAT num_threads 4
STAT num_threads_per_udp 4
STAT stat_key_prefix :
STAT detail_enabled no
STAT reqs_per_event 20
STAT cas_enabled yes
STAT tcp_backlog 1024
STAT binding_protocol auto-negotiate
STAT auth_enabled_sasl no
STAT item_size_max 1048576
STAT maxconns_fast no
STAT hashpower_init 0
STAT slab_reassign no
STAT slab_automove 0
STAT lru_crawler no
STAT lru_crawler_sleep 100
STAT lru_crawler_tocrawl 0
STAT tail_repair_time 0
STAT flush_enabled yes
STAT hash_algorithm jenkins
STAT lru_maintainer_thread no
STAT hot_lru_pct 32
STAT warm_lru_pct 32
STAT expirezero_does_not_evict no
END

Debug an Instance

TODO: Fill in more details