Vercel provides several logging options available for both deployment builds and Serverless Function executions. They can be accessed by selecting either "View Build Logs" or "View Function Logs" from the Project page.
The view logs buttons available on a Vercel project.
Build Logs
Build logs are generated at build time for all deployments. The output is very similar to your frameworks build command, with a few minor additions from the Vercel build system. Once a build has completed, no further logs will be added to this page.
If any errors or warnings are present in the build logs, these will be highlighted with different colors (e.g. yellow for warnings, red for errors). This helps you easily identify the cause of any failed builds and areas you may wish to investigate further.
Build logs are stored indefinitely on each deployment.
Function Logs
Function logs provide logging output for your Serverless Functions. This includes user logging such as console.log, along with details of the request made to the function.
All function logs are generated on-demand. This means they are only sent to the function logs page while it is open in the browser and arrive as each Serverless Function is executed.
Function logs are not stored and will be lost as soon as the functions logs page is navigated away from.
Persistence
The Vercel platfrom, by default, does not store logs that derive from static assets and Serverless Functions, only build logs are stored indefinitely. To store logs in Vercel, we recommend taking advantage of Log Drains through 3rd-party solutions.
Log Drain Solutions
There are several 3rd-party Log Drain Integrations from our Integrations Marketplace that are ready to integrate with Vercel:
Directions on how to set up these integrations can be found within the Integration Guide links or are provided as part of the installation process.
Integration Request
If the Log Drain integration you are looking for is not available, please submit feedback as described here.