Redis OOM error prevents sign in or using server.

Created by: mcdan

• Sourcegraph version: sourcegraph/server:2.11.2
• Platform information:

➜  ~ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.4 LTS
Release:        16.04
Codename:       xenial
➜  ~ docker info
Containers: 24
 Running: 8
 Paused: 0
 Stopped: 16
Images: 55
Server Version: 18.03.1-ce
Storage Driver: aufs
 Root Dir: /var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 462
 Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 773c489c9c1b21a6d78b5c538cd395416ec50f88
runc version: 4fc53a81fb7c994640722ac585fa9ca548971871
init version: 949e6fa
Security Options:
 apparmor
 seccomp
  Profile: default
Kernel Version: 4.4.0-104-generic
Operating System: Ubuntu 16.04.4 LTS
OSType: linux
Architecture: x86_64
CPUs: 16
Total Memory: 15.44GiB
Name: coldplay
ID: TDMA:6IQ6:X2BE:S4NA:RDBL:TGJW:B22K:WAET:5N24:RK3E:CDJT:S7QC
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

WARNING: No swap limit support

Steps to reproduce:

Run the server for a while, with a bunch fo repos. I think I have about 8 or so configured with 5 language servers.

1. Try and login

Expected behavior:

1. Login and use site.

Actual behavior:

1. Login succeeds but you get into a redirect loop: POST /-/sign-in : 200 OK GET /search?toast=integrations : 302 -> /sign-in?returnTo=%2Fsearch%3Ftoast%3Dintegrations POST.... etc, etc. never allows me in.

Meanwhile inside the server container I see 10s of these message per second:

16:06:24   repo-updater | t=2018-10-05T16:06:24+0000 lvl=warn msg="failed to execute redis command" cmd=SETEX error="OOM command not 
allowed when used memory > 'maxmemory'."
16:06:24   repo-updater | t=2018-10-05T16:06:24+0000 lvl=warn msg="failed to execute redis command" cmd=SETEX error="OOM command not 
allowed when used memory > 'maxmemory'."
16:06:24   repo-updater | t=2018-10-05T16:06:24+0000 lvl=warn msg="failed to execute redis command" cmd=SETEX error="OOM command not 
allowed when used memory > 'maxmemory'."
16:06:24   repo-updater | t=2018-10-05T16:06:24+0000 lvl=warn msg="failed to execute redis command" cmd=SETEX error="OOM command not 
allowed when used memory > 'maxmemory'."
16:06:24   repo-updater | t=2018-10-05T16:06:24+0000 lvl=warn msg="failed to execute redis command" cmd=SET error="OOM command not al
lowed when used memory > 'maxmemory'."