Access to view settings of running memcached container

[mjclemente]

I'm passing options into this image, via my Docker-Compose, and I want to confirm that they're being applied (for example, increasing the memory limit).

Is there a way to confirm the settings of the memcached Docker image, once it is up and running?

I've done a lot of searching and everything that I've seen so far involves commands not present on the image (telnet, memcstat) or viewing files that aren't present (/etc/memcached.conf).

Sorry if I'm missing something really obvious.

[wglambert]

If you query /proc it will display information of the host system and won't reflect anything specific to the container

I don't see a way of verifying that memcached implements the runtime arguments given

You can however implement a cgroup alongside that which will be verifiably enforced through docker stats

[mjclemente]

Thanks. If it's not possible to inspect the running configuration of the Docker container, that at least saves me the time of trying to track down how to do it.

Given that it is possible with standard implementations of memcached, I'd suggest that adding/incorporating this functionality might be beneficial.

Again, thanks for the help!

[yosifkit]

Your link to inspect running memcached works just fine if you hit the IP of the container from your host (or another container that has nc) or if via 127.0.0.1 if you forward the port with -p 11211:11211 on the docker run. I can't remember if memcached accounts for cgroup limits or not (like --memory on docker run).

$ docker run -d --name memc memcached
$ ipaddr="$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' memc)"
$ echo "$ipaddr"
172.17.0.3
$ echo "stats settings" | nc "$ipaddr" 11211
STAT maxbytes 67108864
STAT maxconns 1024
STAT tcpport 11211
STAT udpport 0
STAT inter NULL
STAT verbosity 0
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 yes
STAT hashpower_init 0
STAT slab_reassign yes
STAT slab_automove 1
STAT slab_automove_ratio 0.80
STAT slab_automove_window 30
STAT slab_chunk_max 524288
STAT lru_crawler yes
STAT lru_crawler_sleep 100
STAT lru_crawler_tocrawl 0
STAT tail_repair_time 0
STAT flush_enabled yes
STAT dump_enabled yes
STAT hash_algorithm murmur3
STAT lru_maintainer_thread yes
STAT lru_segmented yes
STAT hot_lru_pct 20
STAT warm_lru_pct 40
STAT hot_max_factor 0.20
STAT warm_max_factor 2.00
STAT temp_lru no
STAT temporary_ttl 61
STAT idle_timeout 0
STAT watcher_logbuf_size 262144
STAT worker_logbuf_size 65536
STAT track_sizes no
STAT inline_ascii_response no
STAT ext_item_size 512
STAT ext_item_age 4294967295
STAT ext_low_ttl 0
STAT ext_recache_rate 2000
STAT ext_wbuf_size 4194304
STAT ext_compact_under 0
STAT ext_drop_under 0
STAT ext_max_frag 0.80
STAT slab_automove_freeratio 0.010
STAT ext_drop_unread no
END

[mjclemente]

Perfect. Thanks; I was able to get that working to confirm the settings. Appreciate the insight!