warvariuc's questions

I have a WSGI Python app running in via Gunicorn:

CONFIG = {
    'bind': "unix:{}".format(os.path.join(RUN_DIR, "brain.sock")),
    'preload_app': False,
    # supervisord requires that the child process runs in foreground
    'daemon': False,
    ...
}

It receives HTTP requests via a socket file from Nginx:

server {
    ...
    location / {
        proxy_pass                  http://unix:$root/run/brain.sock:;
        ...
    }

The Gunicorn is run via Supervisord:

[program:myapp]
command = venv/bin/gunicorn -c gunicorn.conf.py myapp.wsgi:application
...

I am thinking of a way to deploy my app without downtime and waiting time. Each worker can take up to 30 seconds to fill up the cache.

My idea to deploy like this:

1. Start a second Gunicorn with new code which would listen to another socket file.

2. Wait until the app starts with all caches filled.

3. Rename the socket file to point to the location used by Nginx. Nginx would still send requests to old socket.

4. Shut down old Gunicorn with old app version. Nginx will see that the socket is closed and will reopen a new socket from the same location.

Will this work?

Am I reinventing the wheel?

I have several servers in Amazon EC2. Having noticed time difference on the instances I have installed ntp. I see /etc/cron.daily/ntp Cron job was added.

Still I notice that, for some reason, the time drifts quite fast.

I am planning to make a symlink in /etc/cron.hourly to /etc/cron.daily/ntp.

Will this help?

I have installed node.js from repositories (v0.10.25, Ubuntu 14.04.3, nodejs-legacy package).

I need a specific version (v0.10.35) for a project.

I installed n (sudo npm install -g n) and installed the needed node.js version using it (sudo n 0.10.35).

Now this thing happens:

$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games

$ which node
/usr/local/bin/node

$ node --version
v0.10.25

$ /usr/local/bin/node --version
v0.10.35

Questions:

1. What is going on here? Shouldn't be the same executable used in both cases with the same version being reported?

2. I can try to uninstall node.js installed from repositories, but is this safe?

set -x or set -v prints every executed command.

How do I get the command printed with the time when the command started executing?