Validate a message for a schema

This document shows you how to validate schemas for Pub/Sub topics.

You can validate that messages adhere to a certain schema, before or after you create a schema resource. This step ensures that the messages you intend to send through a topic associated with a schema actually match before applying the schema.

Before you begin

Understand how Pub/Sub schemas work .
Create a schema .

Required roles and permissions

To get the permissions that you need to validate schema messages and manage them, ask your administrator to grant you the Pub/Sub Editor ( roles/pubsub.editor ) IAM role on your project. For more information about granting roles, see Manage access to projects, folders, and organizations .

This predefined role contains the permissions required to validate schema messages and manage them. To see the exact permissions that are required, expand the Required permissionssection:

Required permissions

The following permissions are required to validate schema messages and manage them:

Create schema: pubsub.schemas.create
Attach schema to topic: pubsub.schemas.attach
Commit a schema revision: pubsub.schemas.commit
Delete a schema or a schema revision: pubsub.schemas.delete
Get a schema or schema revisions: pubsub.schemas.get
List schemas: pubsub.schemas.list
List schema revisions: pubsub.schemas.listRevisions
Rollback a schema: pubsub.schemas.rollback
Validate a message: pubsub.schemas.validate
Get the IAM policy for a schema: pubsub.schemas.getIamPolicy
Configure the IAM policy for a schema: pubsub.schemas.setIamPolicy

You might also be able to get these permissions with custom roles or other predefined roles .

You can grant roles and permissions to principals such as users, groups, domains, or service accounts. You can create a schema in one project and attach it to a topic located in a different project. Ensure that you have the required permissions for each project.

Validate a message for a schema

Console

In the Google Cloud console, go to the Pub/Sub schemaspage.

Go to Schemas

The list of schemas is displayed.
Click the Schema IDof an existing schema.

The Schema detailspage for the schema opens.
In the Revisionssection, click the revision for which you want to validate a message.
In the Detailssection, click Test message.
In the Test messagewindow, select a type of Message encoding.
In the Messagebody, enter a test message.
Click Test.

gcloud

In the Google Cloud console, activate Cloud Shell.

Activate Cloud Shell

At the bottom of the Google Cloud console, a Cloud Shell session starts and displays a command-line prompt. Cloud Shell is a shell environment with the Google Cloud CLI already installed and with values already set for your current project. It can take a few seconds for the session to initialize.
To validate a message against a schema use the gcloud pubsub schemas validate-message command.
```
gcloud pubsub schemas validate-message --message= MESSAGE 
\
    --message-encoding= MESSAGE_ENCODING 
\
    (--schema-name= SCHEMA_NAME 
| \
    --type= TYPE 
\
    (--definition= DEFINITION 
| \
    --definition-file= DEFINITION_FILE 
))
```
Replace the following:
- MESSAGE : message to validate against the schema
- MESSAGE_ENCODING : encoding of the message. Specify one of the following values: binary or json .
- SCHEMA_NAME : name or full path of an existing schema.
- TYPE : type of inline schema. Specify one of the following values: avro or protocol-buffer .
- DEFINITION : inline schema definition.
- DEFINITION_FILE : file containing the schema definition.

What's next

Validate a schema definition when you create a topic