Nginx fails to start with "Illegal instruction (core dumped)" error

[lmakarov]

docksal-vhost-proxy container is running, but nginx fails to start.

Output of docker logs docksal-vhost-proxy:

...
2018-10-19 22:30:31,948 INFO supervisord started with pid 1
2018-10-19 22:30:32,951 INFO spawned: 'nginx' with pid 43
2018-10-19 22:30:32,956 INFO spawned: 'crond' with pid 44
2018-10-19 22:30:32,960 INFO spawned: 'docker-gen' with pid 45
crond: crond (busybox 1.27.2) started, log level 8
2018/10/19 22:30:33 Contents of /etc/nginx/conf.d/vhosts.conf did not change. Skipping notification 'proxyctl notify'
2018/10/19 22:30:33 Watching docker events
2018/10/19 22:30:33 Contents of /etc/nginx/conf.d/vhosts.conf did not change. Skipping notification 'proxyctl notify'
2018-10-19 22:30:33,283 INFO exited: nginx (terminated by SIGILL (core dumped); not expected)
2018-10-19 22:30:34,287 INFO spawned: 'nginx' with pid 54
2018-10-19 22:30:34,288 INFO success: crond entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2018-10-19 22:30:34,288 INFO success: docker-gen entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2018-10-19 22:30:34,611 INFO exited: nginx (terminated by SIGILL (core dumped); not expected)
2018-10-19 22:30:36,616 INFO spawned: 'nginx' with pid 55
2018-10-19 22:30:36,924 INFO exited: nginx (terminated by SIGILL (core dumped); not expected)
2018-10-19 22:30:39,929 INFO spawned: 'nginx' with pid 56
2018-10-19 22:30:40,231 INFO exited: nginx (terminated by SIGILL (core dumped); not expected)
2018-10-19 22:30:41,233 INFO gave up: nginx entered FATAL state, too many start retries too quickly
crond: USER root pid  57 cmd /usr/local/bin/proxyctl cron

Checking nginx config fails with the following error:

$ docker exet -it docker-vhost-proxy nginx -t
Illegal instruction (core dumped)

[lmakarov]

The issue is coming from OpenResty's CPU instruction requirements:
openresty/openresty#267 (comment)

The official OpenResty binary packages require SSE 4.2 support in your CPU

Affected docksal/vhost-proxy versions: 1.3.0+
That's the version where we switched from Nginx + Lua to OpenResty.
Affected Docksal versions: 1.10.0+

As a workaround, vhost-proxy can be downgraded to version 1.2:

$ fin config set --global IMAGE_VHOST_PROXY=docksal/vhost-proxy:1.2
$ fin system reset vhost-proxy

There is no guarantee that pinning the vhost-proxy image long term won't result in incompatibility issues with the latest versions of Docksal.

We should update docs to reflect this.