This assumes you've followed a previous post I made on deploying ghost on dokku.
The upgrade path is actually quite simple.
Dockerfile, update a line that looks similar to this one:
And replace that version string (e.g.
1.6.0 above) to whatever is listed as the latest version on the library/ghost page. You'll want to put in the specific version string to force dokku to redeploy.
At the time of this writing, the latest is
1.8.6. So as an example, your
Dockerfile will look like this:
FROM library/ghost:1.8.6 COPY config.production.json /var/lib/ghost
Commit this file, then
git push dokku. There you have it; you should see that ghost has updated.