34 lines
2.8 KiB
Plaintext
34 lines
2.8 KiB
Plaintext
This example demonstrates routing capabilities of spring-cloud-function when deployed as AWS Lambdas.
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Usually when you deploy configuration (non-custom runtime) with a single function it is automatically recognized and bound as AWS Lambda
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by `org.springframework.cloud.function.adapter.aws.FunctionInvoker` (FunctionInvoker).
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However when you have multiple functions present in your configuration you need to tell `FunctionInvoker` the target function definition.
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You can do so in two different ways.
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1. You can provide `spring_cloud_function_definition` environment variable setting its value to the desired function definition, which could also be composition
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(e.g., `spring_cloud_function_definition=foo|bar`).
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NOTE: Keep in mind though that since AWS does not allow dots `.` and/or hyphens`-` in the name of the environment variable, you can benefit from boot support and simply substitute
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dots with underscores and hyphens with camel case. So for example `spring.cloud.function.definition` becomes `spring_cloud_function_definition`
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and `spring.cloud.function.routing-expression` becomes `spring_cloud_function_routingExpression`.
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2. A more dynamic and recommended approach would be to fallback on auto routing capabilities of spring-cloud function's in AWS environment.
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Basically every time you have more then one function in your configuration, the framework will bind
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[Routing Function](https://docs.spring.io/spring-cloud-function/docs/3.1.3/reference/html/spring-cloud-function.html#_function_routing_and_filtering)
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as AWS Lambda, and all you need to to is provide a routing instruction via Message headers or environment variables. The instructions could themselves be very dynamic, since we support both SpEL and registering a callback interface. For more details on routing mechanisms please refer to
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[Function Routing and Filtering](https://docs.spring.io/spring-cloud-function/docs/3.1.3/reference/html/spring-cloud-function.html#_function_routing_and_filtering) section.
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In this example we have configuration with two functions; `uppercase` and `reverse`.
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When executing from AWS Lambda functions dashboard you can simply provide one of the mentioned properties as environment variables via Configuration tab.
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For example, you can set `spring_cloud_function_routingExpression` environment variable with the value of literal; SpEL expression `'uppercase'` (not the single quotes).
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As for API Gateway, you can also pass routing instructions as Message headers by proving them as HTTP headers.
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You can test it with API Gateway dashboard or (once deployed), you can for example POST to it via `curl`.
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Here is the example of curl command
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```
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curl -X POST https://[. . .].execute-api.eu-west-3.amazonaws.com/route/aws-routing-gw -H "spring.cloud.function.definition: uppercase" -H "Content-Type: application/json" -d '"foo"'
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``` |