AWS CLI check if a lambda function exists

Question

How do I do a one-time check if a lambda function exists via the CLI? I saw this function-exists option - https://docs.aws.amazon.com/cli/latest/reference/lambda/wait/function-exists.html

But it polls every second and returns a failure after 20 failed checks. I only want to check once and fail if it isn't found. Is there a way to do that?

Why not try aws lambda get-function --function-name abc. This will return ResourceNotFoundException if the function does not exist. — krishna_mee2004
– krishna_mee2004, Commented Jun 10, 2019 at 19:48
Either what @krishna_mee2004 suggested or you can list your functions to loop through and find a function if it exists, etc. aws lambda list-functions — Woodrow
– Woodrow, Commented Jun 10, 2019 at 19:52

Nirdosh · Accepted Answer · 2022-11-21 16:39:29Z

17

You can check the exit code of get-function in bash. If the function does not exist, it returns exit code 255 else it returns 0 on success. e.g.

aws lambda get-function --function-name my_lambda
echo $?

And you can use it like below: (paste this in your terminal)

function does_lambda_exist() {
  aws lambda get-function --function-name $1 > /dev/null 2>&1
  if [ 0 -eq $? ]; then
    echo "Lambda '$1' exists"
  else
    echo "Lambda '$1' does not exist"
  fi
}

does_lambda_exist my_lambda_fn_name

edited Nov 21, 2022 at 16:39

answered Jun 11, 2019 at 4:26

Nirdosh

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3 Comments

Roe Over a year ago

my exit code showed up as 254 now on failure lols.

Akshay Lokur Over a year ago

another way is to use function-exists CLI command as described here: awscli.amazonaws.com/v2/documentation/api/latest/reference/…

Yougeshwar Khatri Over a year ago

In my case its not responding anything, I wanted to return the value instead of echo so I have returned $? but it doesn't work

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