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SSM Parameters Are Strings

One important thing to understand about the SSM Parameter Store is that everything is stored as a string.

When you save api.example.com for the host name, SSM stores it as a string. When you set true as a dev tools flag, SSM stores it as the string "true", not a boolean. In this sense, SSM parameters are a lot like environment variables.

Integer (5) → stored as string "5" → your app must parse it
Boolean (true) → stored as string "true" → your app must compare it
Float (3.14) → stored as string "3.14" → your app must parse it
Enum (red) → stored as string "red" → your app must compare it
JSON ({"key": "value"}) → stored as string "{\"key\": \"value\"}" → your app must parse it

Cost check: Standard SSM parameters are free (up to 10,000). This lesson is conceptual; no new parameters required.

Type Casting

When you retrieve a parameter from SSM, you get a string. Your application must then cast the value to the type you need. For example, if you're using Python:

import boto3

# get the parameter from SSM and store the string in secret_str
secret_str = ssm_get_parameter("/SECRETS")

# if the value is supposed to represent an integer, convert it
raw_port_number = ssm_get_parameter("/PORT_NUMBER")
try:
    port = int(raw_port_number)
    print(f"port number is {port}")
except ValueError:
    raise ValueError("raw_port_number turned out not to be a number")