Where do logs wind up in prod?

Questions / Help
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1

A somewhat embarassing question – where do logs wind up in prod (system: ubuntu 18.04)?

I noticed that /var/log/syslog seems to be logging some elixir events, but they don’t contain meaningful string messages, just the metadata (or at least so it seems).

Thanks for the help in advance!

2

Hi @ityonemo!

This would depend upon how you have deployed your application. Could you share more information about your setup?

Thanks!

2 Likes
3

Right. things have changed around logging recently =D

OTP/22; 1.10.2

I just standard MIX_ENV=prod mix release <release name> deliver by untarring to /dir/to/release and use systemd to launch:

[Unit]
Description=My App
After=network.target

[Service]
Type=simple
User=me
WorkingDirectory=/dir/to/release
ExecStart=/dir/to/release/bin/release start
ExecStop=/dir/to/release/bin/release stop
Restart=on-failure

[Install]
WantedBy=multi-user.target

in config.exs, i have:

config :logger, :console,
  format: "$time $metadata[$level] $message\n",
  metadata: [:request_id],
  colors: [error: [:bright, :light_red]]

in prod.exs, I have:

config :logger, backends: [:console]

should I be adding extra logger backends to get them to durable filesystem?

4

I’m not the most familiar with systemd but it has it’s own logging system called journald.

I’m on my phone now so I can’t look up the exact command but if I’m correct you should be able to view the logs from your systemd unit with the journalctl program.

5

Yep, got it. thanks! Haha I just don’t linux system admin enough to remember that, but it’s not a command I’ve never run before =D

6

As you are logging to console then the data ended in journal as @lpil said. You can check them by journalctl -u my_app.service. Just in case, if you want better support for journal logs then you can check out my systemd library which provides some handy utilities.

1 Like
7

I wish I could give solution to both of you, but I think I’m going to give it to @hauleth to mark down the appropriate command for future users.