We've just created and deployed our very first service to our cloud provider.
The service skeleton which Serverless created for us included a function with a corresponding function handler (the handler.js file).
Let's invoke this function to see if the service was deployed successfully.
Run serverless invoke --function hello -p event.json in the service directory to tell Serverless that you want to run the function on the providers infrastructure.
The function will be invoked and returns the result back to Serverless which will print it out on the terminal.
As a result of this you should see the functions message printed out on the console.
You can also change the message returned by your function in handler.js or change the event.json file to see how your function output will change.
You can also check out the invoke command docs for all the details and options.
After you deploy your service, and invoke it to generate some default logs provided by AWS, you can view those logs right from your terminal using the serverless logs command.
Run serverless logs --function hello to fetch the logs of the hello function from CloudWatch. If your function has never been invoked, you may not see any output/logs. For testing we recommend you invoke your function first before logging.
By default, Serverless will fetch all the logs that happened in the past 30 minutes. You can overwrite this behavior by providing extra options. (keep reading!).
The logs will then be displayed on your terminal. By default, AWS logs a START, END & REPORT logs for each invocation, plus of course any logging functionality you have in your code. You should see all these logs on the screen.
The logs command provides different options you can use. Please take a look at the logs command documentation to see what else you can do.
We've just invoked a function through the Serverless CLI on the providers infrastructure and got a message back which was printed on the console.
A service with functions alone is just the beginning. Event sources provide a really easy and great way to empower your service and perform automatic function calls based upon incoming events (e.g. an incoming HTTP request).
Let's take a closer look at how we can use different event sources and attach them to our function.