AWS AppSync Subscription fails during handshake - apollo

Question

I'm trying to set up a graphql subscription but I'm getting the error:
Unhandled GraphQL subscription error Error: Error during subscription handshake
I'm using AWS Cognito User Pools for the authorisation.
To create the Subscription I'm using:
this.subscription = this.props.client.subscribe({ query: gql(onCreateVehicle) }).subscribe({
next: response => {
console.log(response.data.onCreateVehicle);
},
error: error => {
console.warn(error);
}
});
'onCreateVehicle' was automatically generated by Amplify and looks like this:
export const onCreateVehicle = `subscription OnCreateVehicle($owner: String!) {
onCreateVehicle(owner: $owner) {
id
name
events {
items {
id
name
date
isDeleted
owner
}
nextToken
}
sessions {
items {
id
name
isDeleted
createdAt
owner
}
nextToken
}
isDeleted
owner
}
}
`;
Request resolver:
{
"version": "2018-05-29",
"payload": {}
}
Response resolver:
## [Start] Determine request authentication mode **
#if( $util.isNullOrEmpty($authMode) && !$util.isNull($ctx.identity) && !$util.isNull($ctx.identity.sub) && !$util.isNull($ctx.identity.issuer) && !$util.isNull($ctx.identity.username) && !$util.isNull($ctx.identity.claims) && !$util.isNull($ctx.identity.sourceIp) && !$util.isNull($ctx.identity.defaultAuthStrategy) )
#set( $authMode = "userPools" )
#end
## [End] Determine request authentication mode **
## [Start] Check authMode and execute owner/group checks **
#if( $authMode == "userPools" )
## No Static Group Authorization Rules **
## [Start] Owner Authorization Checks **
#set( $isOwnerAuthorized = false )
## Authorization rule: { allow: owner, ownerField: "owner", identityClaim: "cognito:username" } **
#set( $allowedOwners0 = $util.defaultIfNull($ctx.args.owner, null) )
#set( $identityValue = $util.defaultIfNull($ctx.identity.claims.get("username"),
$util.defaultIfNull($ctx.identity.claims.get("cognito:username"), "___xamznone____")) )
#if( $util.isList($allowedOwners0) )
#foreach( $allowedOwner in $allowedOwners0 )
#if( $allowedOwner == $identityValue )
#set( $isOwnerAuthorized = true )
#end
#end
#end
#if( $util.isString($allowedOwners0) )
#if( $allowedOwners0 == $identityValue )
#set( $isOwnerAuthorized = true )
#end
#end
## [End] Owner Authorization Checks **
## [Start] Throw if unauthorized **
#if( !($isStaticGroupAuthorized == true || $isOwnerAuthorized == true) )
$util.unauthorized()
#end
## [End] Throw if unauthorized **
#end
## [End] Check authMode and execute owner/group checks **
$util.toJson(null)
I know it has something to do with authorisation as it didn't throw the handshake error when I removed the #auth from the schema.graphql. Should there be something in the request resolver to handle the authorisation?
Adam

Answer 1

I just had to pass the 'owner' value through the variables object.
subscribeToVehicles: async () => props.data.subscribeToMore({
document: gql(onCreateVehicle),
variables: {
owner: (await Auth.currentSession()).getIdToken().payload.sub
},
...