By default Phoenix stores session data in browser cookies. I don’t know why, but I thought the default was for those cookies to never expire. It turns out by default they expire when the browser session ends. I found this out because my users weren’t able to stay logged in beyond a few days.
It took me a while to find it, but the documentation for Plug.Session options shows you can set the
max_age key to the number of seconds for it to expire. Typically, your
Plug.Session is configured in your
plug Plug.Session, store: :cookie, max_age: 24*60*60*37, # 37 days key: "_my_app_key", signing_salt: "random signing salt"
Now my users will stay logged in for 37 days.