How To

Install the AWS command line interface. Make sure you have the version 1.11.170 or later. If you are unfamiliar with managing Python environments, first try using the bundled AWS CLI installer. You can check your version using:

aws --version

Running the datomic-socks-proxy script with an earlier version of the AWS CLI will result in a generic error message and failure of the script.

If you require multiple versions of the AWS CLI to be installed, then investigate using Python's virtual environments, or the third-party virtualenv solution.

The Datomic CLI tools and ion deployment tools require that you have a set of AWS access keys with permissions to access Datomic. To create these keys, you must have an authorized IAM user. With this user you can then:

• Create access keys
• Add access keys to your environment

Datomic supports the use of named profiles as a credentials source. Additional information about IAM Users and access keys can be found in the AWS security credentials documentation.

Datomic's tools use the Clojure CLI, version 1.10.1.727 or later. You can use clojure -Sdescribe to check your version of the Clojure CLI.

The Clojure getting started page has instructions for installing and upgrading Clojure.

The Datomic ion-dev tools should be installed via an alias in your user deps.edn file, which is normally located at $HOME/.clojure/deps.edn.

• To install the tools, add the datomic-cloud maven repo under your :mvn/repos key:

"datomic-cloud" {:url "s3://datomic-releases-1fc2183a/maven/releases"}

• Then add an :ion-dev entry under your :aliases key with the latest version of ion-dev:

:ion-dev
{:deps {com.datomic/ion-dev {:mvn/version "1.0.316"}}
 :main-opts ["-m" "datomic.ion.dev"]}

The ions tutorial includes a complete .clojure/deps.edn example.

Note that ion-dev configures logging to stderr via slf4j-simple. This is probably adequate for most scenarios, but you, of course, have the full power of SLF4J at your disposal.

The Datomic ion library has to be installed in the deps.edn for each ion project:

• Add the datomic-cloud maven repo under your :mvn/repos key:

"datomic-cloud" {:url "s3://datomic-releases-1fc2183a/maven/releases"}

• Then add the latest version of ion-dev to your :deps:

com.datomic/ion {:mvn/version "1.0.68"}

You do not need to delete the AWS lambdas managed by Datomic Ions to control cost. AWS lambda pricing is entirely usage-based, so if you do not invoke lambdas, they cost nothing. If you want to delete these Lambdas anyway, you can push and deploy an application with an empty lambdas map in ion-config.edn.

Some Datomic CLI tools (e.g. the client access script) continue to run in the foreground once you launch them. For interactive use, the easiest way to manage such tools is simply to kill them with Ctrl-C when they are no longer needed.

If you are building automation around scripts, you can of course use all the ordinary Unix facilities, e.g.

• You can use pkill [script-name] to kill a script from another terminal
• You can use e.g. nohup [script-command] [script-args] & to launch a script in the background, directing its output to nohup.out
  • Currently running processes can be listed with jobs and brought to the foreground with fg $pid where pid is the process number listed in jobs

Every Datomic system resides in a single AWS region and has a unique system name within that region. The system name is the Stack Name used to launch the Datomic storage stack.

If you did not start Datomic yourself, you can find the available systems from the CLI or the AWS Console:

• From the CLI, use the datomic cloud list-systems command
• From the console browse to CloudFormation console

You can list the names of all running Datomic nodes using:

• Utilize the datomic system list-instances <system> command, replacing <system> with your system name

or

• Utilize the following AWS CLI command, replacing [region] with the region you want to query:

aws ec2 describe-instances --region [region] --filters "Name=tag-key,Values=datomic:tx-group" "Name=instance-state-name,Values=running" --query 'Reservations[*].Instances[*].[Tags[?Key==`datomic:system`].Value]' --output text

If you start a Datomic system with split stacks, then it has one or more compute groups. A compute group's name is the name of the CloudFormation stack you used to create the group.

You can query compute groups for a system from the CLI, or browse them in the AWS Console:

• From the CLI, use the datomic system list-instances <system> command
• Browse all your CloudFormation stacks in the AWS CloudFormation console

Every Datomic compute group has an associated application for ion deployments. You specify the application name when you create a compute group.

If you did not start the compute group, you can find the application name by browsing your compute group in the AWS CloudFormation console and looking for the ApplicationName value in the Parameters tab.

Every Datomic system has its own S3 bucket for configuration and data storage.

You can find this S3 bucket by browsing the Outputs tab of your storage stack in the AWS Console and looking for the S3DatomicArn output.

All Datomic systems in a region share a common S3 bucket for ion deployment. This bucket has a datomic:code AWS tag.

You can find this bucket by creating a resource group in the AWS Console:

• Make sure you are working in the region you want to query
• Create a tag-based resource group
• Select a resource type of AWS::S3::Bucket
• Search for a tag named datomic:code
• Give your group a name, e.g. DatomicCodeBucket
• Create your group

Datomic's CloudFormation templates create outputs describing the resources that they manage. To view these outputs, go to the CloudFormation console, or query them from the AWS CLI. The following example query lists the outputs for a stack named "inventory-primary":

aws cloudformation describe-stacks --stack-name inventory-primary

Information about the compute groups of a system can be found using describe-groups:

datomic system describe-groups <system>

Every Datomic database starts with a base schema, whose identifiers are prefixed with :db. When the Datomic team enhances the base schema, all databases created with new versions of Datomic get the enhancements automatically.

Existing databases do not automatically incorporate enhancements to the base schema. To upgrade existing databases to use new base schema, first upgrade all compute groups (primary and query) to the minimum version of Datomic required for the base schema features you want:

Once you have upgraded all compute groups, you can upgrade an existing database to use the latest base schema by passing the :upgrade-schema action to administer-system. For example:

(d/administer-system client {:db-name "movies"
                             :action :upgrade-schema})

Upgrading a schema is an idempotent operation, so it will not harm your data to call it more than once. That said, treat administer-system as a potentially expensive operation. Call it only when you need it, not before every call to connect.

Once you have used a base schema feature in a particular database, do not run any compute group for that system on versions of Datomic older than the features used. See the table above.