I forked a heroku application (on the cli, using heroku fork). However, when I checked the fork application's config vars, the DATABASE_URL that it's set to is exactly the same as in the original application which I forked.
Can I push database schema changes to the new fork without affecting the original application? Or is there a need to fork the database as well?
From the rather obscure warning in the Heroku documentation, it sounds like sometimes the Heroku Postgres setup in the target app is not 100% correct after forking your app (i.e. as you observed, your DATABASE_URL is still pointing at the original app's DB, instead of at the forked app's DB).
The remedy in this case is to promote the new DB (i.e. your new HEROKU_POSTGRESQL_COLOR_URL) to be the primary DB for the forked app, using heroku pg:promote, e.g:
heroku pg:promote HEROKU_POSTGRESQL_COLOR_URL --app theForkedApp
Related
I am sharing a MongoDB between a few heroku apps and would like to move the ownership/billing to another app.
I have tried attaching (heroku addons:attach) to the receiving app and then using the heroku addons:detach command on the billing app, but this doesn't work.
Heroku support just confirmed that it is not possible to change the billing app for an add-on.
You can attach the add-on to other apps, but if you delete the original billing app then it will instantly delete your database without warning - even if it is attached to other active apps.
Some add-ons like Postgres offer a fork option, so you may be able fork, reconnect to the new instance, and delete the old database. The Postgres fork command looks like:
heroku addons:create heroku-postgresql:standard-0 --fork the-old-app-name::HEROKU_POSTGRESQL_CHARCOAL --app the-new-app-name
Where HEROKU_POSTGRESQL_CHARCOAL is the ENV variable name of your old database on your old app.
I have Rails 3.2 application hosted on Heroku. My application contains two databases (one for my model, the second is a kind of a dictionary with static data).
I need to push the second database (dictionary) to Heroku, but when I try db:push Heroku thinks that I'm going to push the first database (with Rails model).
The question is - how could I specify that I want to push my local database dictionary.sqlite to heroku dictionary.pg?
You could use the Heroku pg:transfer plugin which will let you set the target destination by it's URL.
https://github.com/ddollar/heroku-pg-transfer
Alternatively, use psql client locally but restore to the heroku pg isntance.
Don't use db:push/pull; those methods are deprecated. Use pgbackups:capture/restore for things like this. It accepts the HEROKU_POSTGRESQL_COLOR as part of the command:
$ heroku pgbackups:restore HEROKU_POSTGRESQL_COLOR 'https://example.com/data.dump' --app app-name
See Importing and Exporting Heroku Postgres Databases with PG Backups for more detailed explanation.
Also, heroku-pg-transfer has been integrated into pg-extras, check that out here: https://github.com/heroku/heroku-pg-extras
What is the recommended way to upgrade a Heroku Postgres production database to 9.2 with minimal downtime? Is it possible to use a follower, or should we take the pgbackups/snapshots route?
Until logical followers in 9.4, you'll have to dump and restore (for the reasons Craig describes). You can simplify this with pgbackups:transfer. The direct transfer is faster than dump and restore, but know that you won't have a snapshot to keep.
The script below is basically Heroku's Using PG Backups to Upgrade Heroku Postgres Databases
with modification for pgbackups:transfer. (If you have multiple instances, say a staging server, add "-a" or "--remote" to each Heroku line to specify which server.)
# get the pgbackups plugin
heroku plugins:install git://github.com/heroku/heroku-pg-extras.git
# provision new db
heroku addons:add heroku-postgresql:crane --version=9.2
# wait for it to come online, make note of new color
heroku pg:wait
# prevent new data from arriving during dump
heroku ps:scale worker=0 web=0
heroku maintenance:on
# copy over the DB. could take a while.
heroku pgbackups:transfer OLDCOLOR NEWCOLOR
# promote new database as default for DATABASE_URL
heroku pg:promote NEWCOLOR
# start everything back up and test
heroku ps:scale worker=N web=N
heroku maintenance:off
heroku open
# remove old database
heroku addons:remove HEROKU_POSTGRESQL_OLDCOLOR
Note that if you compare your data size between them, the new one may be much smaller because of efficiencies in 9.2. (My 9.2 was about 70% of the 9.1.)
Heroku followers are, AFAIK, just PostgreSQL streaming replica servers. This means you can't use them across versions, you must have binary-compatible databases.
The same techniques should apply as ordinary PostgreSQL, except that you may not be able to use pg_upgrade on Heroku. This requires shell (ssh, etc) access as the postgres user on the system that hosts the database, so I doubt it's possible on Heroku unless they've provided a tool to run pg_upgrade for you. I can't find much information on this.
You will probably have to look at using Slony-I, Bucardo, or another trigger-based replication solution to do the upgrade unless you can find a way to run pg_upgrade on a Heroku database instance. The general idea is that you set up a new 9.2 instance, use Slony to clone data from the 9.1 instance into it, then once they're fully in sync you stop the 9.1 instance, remove the Slony triggers, and switch clients over to the 9.2 instance.
Search for more information on "postgresql low downtime upgrade slony" etc, see how you go.
In the migration Guide the recommended approaches for migrating databases don't include just changing the DATABASE_URL in the new instance. If you have a dedicated database in Bamboo, and want to use the same in Cedar, is there a problem in just pointing the DATABASE_URL in Cedar to the same DATABASE_URL?
Thanks
If you delete the bamboo app, your DB will likely be decommissioned. If you maintain your bamboo app, with just a single dyno and no workers it should be free, and the approach you suggest should work.
A bad side of pushing to Heroku is that I must push the code (and the server restarts automatically) before running my db migrations.
This can obviously cause some 500 errors on users navigating the website having the new code without the new tables/attributes: the solution proposed by Heroku is to use the maintenance mode, but I want a way with no downside letting my webapp running everytime!
Is there a way? For example with Capistrano:
I prepare the code to deploy in a new dir
I run (backward) migrations and the old code continue to work perfectly
I swith mongrel instance to the new dir and restart the server
...and I have no downtime!
You could setup a second Heroku app which points to the same DB as your primary production app and use the secondary app to run your DB migrations without interrupting production (assuming the migrations don't break the previous version of your app).
Let's call the Heroku apps PRODUCTION and STAGING.
Your deploy sequence would become something like:
Deploy new code to STAGING
git push heroku staging
Run database migrations on STAGING (to update PROD db)
heroku run -a staging-app rake db:migrate
Deploy new code to PRODUCTION
git push heroku production
The staging app won't cost you anything since you won't need to exceed Heroku's free tier and it would be pretty trivial to setup a rake deploy script to do this for you automatically.
Good luck!
If you're able to live with two versions of the same app live at the same time, Heroku now has a preboot feature.
https://devcenter.heroku.com/articles/preboot
The only method to improve the process somewhat is what this guy suggests. This is still not a hot deploy scenario though:
http://casperfabricius.com/site/2009/09/20/manage-and-rollback-heroku-deployments-capistrano-style/
One thing I would suggest is pushing only your migrations up to Heroku first and running them before you push your codebase. This would entail committing the migrations as standalone commits and manually pushing them each time (which is not ideal). I'm very surprised there is not a better solution to this issue with all of the large apps hosted on Heroku now.
You actually will have some downtime when Heroku restarts your app. They have a new feature called Preboot that starts up new dynos before taking out the old ones: https://devcenter.heroku.com/articles/labs-preboot/
As for database migrations, that article links to this one on how to deal with that issue: http://pedro.herokuapp.com/past/2011/7/13/rails_migrations_with_no_downtime/
I first commit the migrations, run them, then push the rest of the code. Add a single file like so:
git commit -m 'added migration' -- db/migrate/2012-your-migration.rb
Heroku can't deploy by capistrano. You are block by tool released by heroku.
The no downtime system is impossible in all cases. How change your schema with big change without stop your server. If you don't stop it, you can avoid some change and your database can be inconsistent. SO the using of maintenance page is a normal solution.
If you want a little solution to avoid problem is a balancing in two server. One with only read database during your migration. You can switch to this instance during your migration avoiding the maintenance page. After your migration you come back to your master.
Right now I don't see any possibility to do this without downtime. I hate it too.
This console command does it in the smallest amount of time I can think of
git push heroku master &&
heroku maintenance:on &&
sleep 5 &&
heroku run rails db:migrate &&
sleep 3 &&
heroku ps:restart &&
heroku maintenance:off
git push heroku master to push the master branch to heroku
heroku maintenance:on to put on maintenance so no 500s
sleep 5 to let the dynos start up the new code (without it, the migration might fail)
heroku run rails db:migrate to do the actual migration
heroku ps:restart out of experience the restart makes sure the new dynos have the latest schema
heroku maintenance:off turns of the maintenance
You might have to add -a <app name> behind all heroku commands if you have multiple apps.
Just one command will run these in series in terminal on Mac OSX.