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Configure data store

Before you can build and deploy OpenWhisk, you must configure a backing data store. The system supports any self-managed CouchDB instance or Cloudant as a cloud-based database service.

Using CouchDB

If you are using your own installation of CouchDB, make a note of the host, port, username and password. Then provision a custom Vagrant box by following the instructions for a persistent CouchDB. In case you already have a Vagrant box, maybe using default settings you can simply adjust the existing db settings. Within your openwhisk/ansible directory, edit the file db_local.ini as appropriate. If you do not find db_local.ini, refer to Setup to create it. Note that:

  • the username must have administrative rights
  • the CouchDB instance must be accessible over http or https (the latter requires a valid certificate)

Using an ephemeral CouchDB container

To try out OpenWhisk without managing your own CouchDB installation, you can start a CouchDB instance in a container as part of the OpenWhisk deployment. We advise that you use this method only as a temporary measure. Please note that:

  • no data will persist between two creations of the container
  • you will need to run ansible-playbook couchdb.yml every time you clean or teardown the system (see below)
  • you will need to initialize the data store each time (ansible-playbook initdb.yml, see below)

Detailed instructions are found in the Ansible README.

Using Cloudant

As an alternative to a self-managed CouchDB, you may want to try Cloudant which is a cloud-based database service.

Create a Cloudant account via IBM Cloud

Sign up for an account via IBM Cloud. IBM Cloud offers trial accounts and its signup process is straightforward so it is not described here in detail. Using IBM Cloud, the most convenient way to create a Cloudant instance is via the cf command-line tool. See here for instructions on how to download and configure cf to work with your IBM Cloud account.

When cf is set up, issue the following commands to create a Cloudant database.

# Create a Cloudant service
cf create-service cloudantNoSQLDB Shared cloudant-for-openwhisk

# Create Cloudant service keys
cf create-service-key cloudant-for-openwhisk openwhisk

# Get Cloudant username and password
cf service-key cloudant-for-openwhisk openwhisk

Make note of the Cloudant username and password from the last cf command so you can create the required db_local.ini.

Setting the Cloudant credentials

Provision a custom Vagrant box by following the instructions for Cloudant.

If you already have an existing box, you can simply modify the settings in the VM. Within your openwhisk/ansible directory, edit the file db_local.ini as appropriate.

Note that:

  • the protocol for Cloudant is always HTTPS
  • the port is always 443
  • the host has the schema <your cloudant user>.cloudant.com

More details on customizing db_local.ini are described in the ansible readme.

Initializing database for authorization keys

The system requires certain authorization keys to install standard assets (i.e., samples) and provide guest access for running unit tests. These are called immortal keys. If you are using a persisted data store (e.g., Cloudant), you only need to perform this operation once. If you are using an ephemeral CouchDB container, you need to run this script every time you tear down and deploy the system.

# Work out of your openwhisk directory
cd /your/path/to/openwhisk/ansible

# Initialize data store containing authorization keys
ansible-playbook initdb.yml

The playbook will create the required data structures to prepare the account to be used. Don't worry if you are unsure whether or not the db has already been initialized. The playbook won't perform any action on a db that is already prepared.

The output of the playbook will look similar to this (using CouchDB in this example):

PLAY [ansible] *****************************************************************

TASK [setup] *******************************************************************
Tuesday 14 June 2016  16:33:51 +0200 (0:00:00.017)       0:00:00.017 **********
ok: [ansible]

TASK [include] *****************************************************************
Tuesday 14 June 2016  16:33:51 +0200 (0:00:00.262)       0:00:00.280 **********
included: /your/path/to/openwhisk/ansible/tasks/initdb.yml for ansible

TASK [check if the immortal subjects db with CouchDB exists?] ******************
Tuesday 14 June 2016  16:33:51 +0200 (0:00:00.060)       0:00:00.340 **********
ok: [ansible]

TASK [create immortal subjects db with CouchDB] ********************************
Tuesday 14 June 2016  16:33:51 +0200 (0:00:00.329)       0:00:00.670 **********
ok: [ansible]

TASK [recreate the "full" index on the "auth" database] ************************
Tuesday 14 June 2016  16:33:52 +0200 (0:00:00.166)       0:00:00.837 **********
ok: [ansible]

TASK [recreate necessary "auth" keys] ******************************************
Tuesday 14 June 2016  16:33:52 +0200 (0:00:00.162)       0:00:01.000 **********
ok: [ansible] => (item=guest)
ok: [ansible] => (item=whisk.system)

PLAY RECAP *********************************************************************
ansible                    : ok=6    changed=0    unreachable=0    failed=0

Database backups

Backups are essential for running a production system of any sort and size. replicateDbs.py provides an easy to use interface that uses CouchDBs replication mechanism to create snapshot replications, continuous replications and a mechanism to play a snapshot back into the production system.

All commands for replicateDbs.py take two standard parameters:

  • --sourceDbUrl: Server URL of the source database, that has to be backed up. E.g. 'https://xxx:[email protected]:443'.
  • --targetDbUrl: Server URL of the target database, where the backup is stored. Like sourceDbUrl.

Creating a snapshot

To create a snapshot, call replicateDbs.py with the replicate command. It takes 3 parameters:

  • --dbPrefix: The prefix of all databases that should be backed up.
  • --expires: Removes all snapshots older than the provided amount of seconds.
  • --continuous: If specified, the created replication will be continuous.

Using that command will result in a replication for every database that matches the --dbPrefix flag, which is then prefixed with backup_${TIMESTAMP_IN_SECONDS}_. TIMESTAMP_IN_SECONDS is the date of generation, which is also used to determine expired snapshots that should be deleted.

Note: Replications are created asynchronously. The script will exit very fast while the replication could take a while.

Replaying a snapshot

To replay a snapshot, swap --sourceDbUrl and --targetDbUrl and call the script with the replay command. That command takes only 1 parameter: --dbPrefix to determine which backup to play back. Matching databases will be replicated back to the target database with the backup_${TIMESTAMP_IN_SECONDS}_ removed, so they'd look just like the original database.

Database migration to new schema

To reduce the memory consumption in the OpenWhisk controller, all code inlined in action documents has been moved to attachments. This change allows only metadata for actions to be fetched instead of the entire action. Though the OpenWhisk controller supports both mentioned schemas, it is ideal to update existing databases to use the new schema for memory consumption relief.

Run moveCodeToAttachment.py to update actions in an existing database to the new action schema. Two parameters are required: