logs.md

Retrieving Action Logs

Application logs are essential to debugging production issues. In IBM Cloud Functions, all output written to stdout and stderr by actions is available in the activation records.

Creating activation logs

1. Create a new action named logs from the following source files.

   function main(params) {
       console.log("function called with params", params)
       console.error("this is an error message")
       return { result: true }
   }

   ibmcloud fn action create logs logs.js

   ok: created action logs

2. Invoke the logs action to generate some logs.

   ibmcloud fn action invoke -r logs -p hello world

   {
       "result": true
   }

Accessing activation logs

Retrieve activation record to verify logs have been recorded.

ibmcloud fn activation get --last

ok: got activation 9fc044881705479580448817053795bd
{
    ...
    "logs": [
        "20xx-11-14T09:49:03.021Z stdout: function called with params { hello: 'world' }",
        "20xx-11-14T09:49:03.021Z stderr: this is an error message"
    ],
    ...
}

Logs can also be retrieved without showing the whole activation record, using the activation logs command.

ibmcloud fn activation logs --last

20xx-11-14T09:49:03.021404683Z stdout: function called with params { hello: 'world' }
20xx-11-14T09:49:03.021816473Z stderr: this is an error message

Polling activation logs

Activation logs can be monitored in real-time, rather than manually retrieving individual activation records.

1. In another terminal, run the following command to monitor logs from the logs actions.

   ibmcloud fn activation poll

   Enter Ctrl-c to exit.
   Polling for activation logs
   

2. In your original terminal, run the following command multiple times.

   ibmcloud fn action invoke logs -p hello world

   ok: invoked /_/logs with id 0e8d715393504f628d715393503f6227
   

3. Check the output from the poll command to see the activation logs.

   Activation: 'logs' (ae57d06630554ccb97d06630555ccb8b)
   [
       "20xx-11-14T09:56:17.8322445Z stdout: function called with params { hello: 'world' }",
       "20xx-11-14T09:56:17.8324766Z stderr: this is an error message"
   ]
   
   Activation: 'logs' (0e8d715393504f628d715393503f6227)
   [
       "20xx-11-14T09:56:20.8992704Z stdout: function called with params { hello: 'world' }",
       "20xx-11-14T09:56:20.8993178Z stderr: this is an error message"
   ]
   
   Activation: 'logs' (becbb9b0c37f45f98bb9b0c37fc5f9fc)
   [
       "20xx-11-14T09:56:44.6961581Z stderr: this is an error message",
       "20xx-11-14T09:56:44.6964147Z stdout: function called with params { hello: 'world' }"
   ]