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I am working on a Django app and have now reached the point of setting up my deployment process. I would like to automate this as much as possible and as such am looking for any help I can get in terms of database management. As I see it, this is the rough outline of the process I would like to automate: 1. back up the current database on the live server 2. merge the structure of the dev and deploy databases so as to keep only the data in the deployment db but update the structure to match the dev db

I have considered simply applying all of the new migrations from dev to the live db however I fear that this will result in a series of errors due to default values and such.

Any insights into where I could look to get started would be greatly appreciated!

Veronica Andric
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  • You should look at creating data migrations in between the schema migrations. Basically you can use Django's models to update / manipulate the data. For example the migration might add a field to a model, the second would be a data migration to populate the new field and a third migration may remove a field that was no longer required. https://docs.djangoproject.com/en/1.10/topics/migrations/#data-migrations. Doing it this way means that you can control the order when schema changes and data changes happen. – wobbily_col Jan 10 '17 at 11:20

1 Answers1

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Here are the commands. You can use whatever your favorite automation language is.

  1. back up the current database on the live server 
mysqldump -u username -p database_name | gzip -c > live_server_backup.sql.gz
  1. merge the structure of the dev and deploy databases so as to keep only the data in the deployment db but update the structure to match the dev db

For this, our typical process is to actually just apply the migrations. If you are at all worried about the migrations, you can do this on your dev server:

# 1.  backup live database
mysqldump -u username -p database_name | gzip -c > live_server_backup.sql.gz  

# 2.  Transfer the backup to the dev server using scp
# 3.  backup dev database
mysqldump -u username -p database_name | gzip -c > dev_server_backup.sql.gz

# 4.  Load the live database into your dev database server
mysql -u username -p -e 'drop database database_name ; create database database_name'
gunzip -c live_server_backup.sql.gz | mysql -u username -p database_name

# 5.  Apply all migrations against dev-copy of live server
cd /path/to/django/root
. bin/activate # if you are using virtualenv
python manage.py migrate

This way you can test whether any of your migrations will cause issues on the live server without actually affecting the live server itself. After you have confirmed, you can:

# 6. 
mysql -u username -p -e 'drop database database_name; create database database_name;'
# 7. Restore dev database
gunzip -c dev_server_backup.sql.gz | mysql -u username -p database_name
2ps
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