Get Application Logs
Retrieving logs of your Spin applications at runtime is crucial to understand runtime behavior and for gathering insights.
Retrieving Logs of Your Application
Use the spin aka logs command, to retrieve logs of your Spin application deployed to Fermyon Wasm Functions.
If you invoke the command from within the directory of your Spin application (the directory in which your spin.toml file is located), it will - by default - load all logs of the current Spin application.
If the command is invoked outside the application directory, or if you want to receive log messages of a particular Spin application running on Fermyon Wasm Functions, you must explicitly specify the name of the application using the --app flag:
$ spin aka logs --app hello-fermyon-wasm-functions
The spin aka logs command, will print all log messages to stdout as shown here:
2025-01-16 13:31:46 [hello-fermyon-wasm-functions] 2025/01/16 13:31:36 INFO GET https://11077e3b-d632-4df3-921f-f7ebefb9aaca.aka.fermyon.tech/hello: Handled by handle_hello func
2025-01-16 13:31:48 [hello-fermyon-wasm-functions] 2025/01/16 13:31:47 INFO POST https://11077e3b-d632-4df3-921f-f7ebefb9aaca.aka.fermyon.tech/greet: Handled by handle_greet func
2025-01-16 13:31:48 [hello-fermyon-wasm-functions] 2025/01/16 13:31:47 WARN Greet invoked with invalid payload. Will respond with HTTP 400
2025-01-16 13:32:04 [hello-fermyon-wasm-functions] 2025/01/16 13:31:56 INFO POST https://11077e3b-d632-4df3-921f-f7ebefb9aaca.aka.fermyon.tech/greet: Handled by handle_greet func
The log messages shown above have been generated using the log/slog package by a Spin application written in Go. Technically, everything your Spin application writes to stdout and stderr will be captured by Fermyon Wasm Functions and made accessible via the spin aka logs command.