I am trying to setup an AWS lambda that will start an SSM session in my EC2 instance and run a command. For simplicity right now I am just trying to run ls. Here is my lambda function:
import json
import boto3
def lambda_handler(commands, context):
"""Runs commands on remote linux instances
:param client: a boto/boto3 ssm client
:param commands: string, each one a command to execute on the instance
:return: the response from the send_command function (check the boto3 docs for ssm client.send_command() )
"""
client = boto3.client('ssm')
print ("Hello world")
resp = client.send_command(
DocumentName="AWS-RunShellScript",
# Would normally pass commands param here but hardcoding it instead for testing
Parameters={"commands":["ls"]},
InstanceIds=["i-01112223333"],
)
return resp
However when I run "Test" on this function I get the following log output:
START RequestId: d028de04-4004-4a0p-c8d2-975755c84777 Version: $LATEST
Hello world
[ERROR] Runtime.MarshalError: Unable to marshal response: datetime.datetime(2020, 5, 12, 19, 34, 36, 349000, tzinfo=tzlocal()) is not JSON serializable
END RequestId: d028de04-4asdd4-4a0f-b8d2-9asd847813
REPORT RequestId: d42asd04-44d4-4a0f-b9d2-275755c6557 Duration: 1447.76 ms Billed Duration: 1500 ms Memory Size: 128 MB Max Memory Used: 76 MB Init Duration: 301.68 ms
I am not sure what this Runtime.MarshalError: Unable to marshal response error means or how to fix it.
The payload I'm passing to run the Test lambda shouldn't matter since I'm not using the commands parameter but it is:
{
"command": "ls"
}
Any help would be appreciated
To troubleshoot Lambda code errors You can use CloudWatch to view all logs generated by your function's code and identify potential issues. For more information, see Accessing Amazon CloudWatch Logs for AWS Lambda.
When a function returns an error after execution, Lambda attempts to run it two more times by default. With Maximum Retry Attempts, you can customize the maximum number of retries from 0 to 2. This gives you the option to continue processing new events with fewer or no retries.
If Lambda encounters an error, it returns an exception type, message, and HTTP status code that indicates the cause of the error. The client or service that invoked the Lambda function can handle the error programmatically, or pass it along to an end user.
Try the following:
return json.loads(json.dumps(resp, default=str))
This will dump resp as JSON and use the str
function for datetime serialization. Then it restores back the same object but instead of datetime object you will get strings that can be serialized.
The error has pretty clear wording, you're just fixating on wrong part.
I assume you use the resp
object somewhere down the line and that part tries to do something like json.load()
or related.
datetime.datetime(2020, 5, 12, 19, 34, 36, 349000, tzinfo=tzlocal()) is not JSON serializable
This is a common error for people running into datetime
for the first time, here's pretty comprehensive question about it: How to overcome "datetime.datetime not JSON serializable"?
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