Installing Dgraph on Ubuntu 22.04

In this Dgraph tutorial, learn how to install the database on Ubuntu 22.04, add a schema and access the GraphQL endpoint.

Graph databases are databases explicitly designed for the analysis of relationships. You can use graph databases if you are interested in the analysis of relationships between data — not to build the data store for your typical backend application.

Dgraph is an open-source, scalable, distributed, highly available and fast graph database, designed from the ground up to be run in production.

Dgraph consists of different nodes such as Zero, Alpha, and Ratel each node serves a different purpose.

• Dgraph Zero control the Dgraph database cluster. It assigns Alpha nodes to groups, re-balances data between groups, handles transaction timestamp and UID assignment.
• Dgraph Alpha hosts predicates and indexes. Predicates are either the properties associated with a node or the relationship between two nodes. Indexes are the tokens that can be associated with the predicates to enable filtering using appropriate functions.
• Ratel is the UI to run queries, mutations, and altering schema.

• Familiarize yourself with our Getting Started guide and complete the steps for setting your Linode’s hostname and timezone.

• Complete the sections of our Securing Your Server to create a standard user account, harden SSH access and remove unnecessary network services.

• Update your system:

    sudo apt-get update && sudo apt-get upgrade
  

• Install Docker Engine

You can install Dgraph using the Docker Compose.

1. If you not already installed Docker Compose, install it using:

   sudo apt install docker-compose
   

2. Download the Dgraph docker-compose.yml file:

   wget https://github.com/dgraph-io/dgraph/raw/main/contrib/config/docker/docker-compose.yml
   

   By default only the localhost IP 127.0.0.1 is allowed. When you run Dgraph on Docker, the containers are assigned IPs and those IPs need to be added to the allowed list.

3. Add a list of IPs allowed for Dgraph so that you can create the schema. Use an editor of your choice and add the <ip_address> of the local host in docker-compose.yml file:

   File: /docker-compose.yml

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   # This Docker Compose file can be used to quickly bootup Dgraph Zero # and Alpha in different Docker containers. # It mounts /tmp/data on the host machine to /dgraph within the # container. You will need to change /tmp/data to a more appropriate location. # Run `docker-compose up` to start Dgraph. version: "3.2" services: zero: image: dgraph/dgraph:latest volumes: - /tmp/data:/dgraph ports: - 5080:5080 - 6080:6080 restart: on-failure command: dgraph zero --my=zero:5080 alpha: image: dgraph/dgraph:latest volumes: - /tmp/data:/dgraph ports: - 8080:8080 - 9080:9080 restart: on-failure command: dgraph alpha --my=alpha:7080 --zero=zero:5080 --security whitelist=<ip_address> ratel: image: dgraph/ratel:latest ports: - 8000:8000

4. Run the docker-compose command to start the Dgraph services in the docker container:

   sudo docker-compose up
   

   After Dgraph is installed on Docker, you can view the images and the containers running in Docker for Dgraph.

5. View the containers running for Dgraph using:

   sudo docker ps -a
   

   An output similar to the following appears:

      CONTAINER ID   IMAGE                  COMMAND                  CREATED
      4b67157933b6   dgraph/dgraph:latest   "dgraph zero --my=ze…"   2 days ago
      3faf9bba3a5b   dgraph/ratel:latest    "/usr/local/bin/dgra…"   2 days ago
      a6b5823b668d   dgraph/dgraph:latest   "dgraph alpha --my=a…"   2 days ago
      

6. To access the Ratel UI for queries, mutations, and altering schema, open your web browser and navigate to http://<LINODE_IP_ADDRESS>:8000.

7. Click Launch Latest to access the latest stable release of Ratel UI.

8. In the Dgraph Server Connection dialog that set the Dgraph server URL as http://<LINODE_IP_ADDRESS>:8080

9. Click Connect . The connection health appears green.

10. Click Continue to query or run mutations.

1. Use an editor of your choice and add the following content in file named schema.graphql, to create a schema on a local computer:

   File: /schema.graphql

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   type Product { productID: ID! name: String @search(by: [term]) reviews: [Review] @hasInverse(field: about) } type Customer { username: String! @id @search(by: [hash, regexp]) reviews: [Review] @hasInverse(field: by) } type Review { id: ID! about: Product! by: Customer! comment: String @search(by: [fulltext]) rating: Int @search }

2. Add this schema to Dgraph using the following command:

   curl -X POST <LINODE_IP_ADDRESS>:8080/admin/schema --data-binary '@schema.graphql'
   

   When the schema is added successfully a message similar to the following appears:

   {"data":{"code":"Success","message":"Done"}}%
   

In the Ratel UI go to Schema and the schema that you added appears in Schema.

You can access that GraphQL endpoint with any of the great GraphQL developer tools such as GraphQL Playground, Insomnia, GraphiQL and Altair. The GraphQL endpoint is http://<LINODE_IP_ADDRESS>:8080/graphql. For more information about getting started with GraphQL mutations and queries, see the Dgraph quick start guide.

More Information

You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

• Official Dgraph Documentation
• GraphQL