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When debugging errors and outages, looking at the logs emitted by JupyterHub is very helpful. This document tries to document some common log messages, and what they mean. I currently added just one log message, but we can add more over time. Ref https://github.com/2i2c-org/infrastructure/issues/1081 where this would've been useful troubleshooting
33 lines
1.5 KiB
Markdown
33 lines
1.5 KiB
Markdown
# Common log messages emitted by JupyterHub
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When debugging errors and outages, looking at the logs emitted by
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JupyterHub is very helpful. This document tries to document some common
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log messages, and what they mean.
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## Failing suspected API request to not-running server
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Your logs might be littered with lines that might look slightly scary
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```
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[W 2022-03-10 17:25:19.774 JupyterHub base:1349] Failing suspected API request to not-running server: /hub/user/<user-name>/api/metrics/v1
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```
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However, what this most likely means is that the user's server has
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stopped running but they still have a browser tab open. This is
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extremely common - for example, you might have 3 tabs open, and shut
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your server down via one. Or you closed your laptop, your server was
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culled for inactivity, and then you reopen your laptop again! The
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client side code (JupyterLab, Classic Notebook, etc) does not know
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yet that the server is dead, and continues to make some API requests.
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JupyterHub's architecture means that the proxy routes all requests that
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don't go to a running user server to the hub process itself. The hub
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process then explicitly returns a failure response, so the client knows
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that the server is not running anymore. This is used by JupyterLab to
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tell you your server is not running anymore, and offer you the option
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to let you restart it.
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Most commonly, you'll see this in reference to the `/api/metrics/v1`
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URL, used by [jupyter-resource-usage](https://github.com/jupyter-server/jupyter-resource-usage).
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So for the most part, this log line is pretty benign!
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