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128 lines
3.9 KiB
Markdown
128 lines
3.9 KiB
Markdown
(topic-idle-culler)=
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# Culling idle notebook servers
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The idle culler automatically shuts down user notebook servers when they have
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not been used for a certain time period, in order to reduce the total resource
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usage on your JupyterHub.
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The notebook server monitors activity internally
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and notifies JupyterHub of recent activity at certain time intervals (the activity interval).
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If JupyterHub has not been notified of any activity after a certain period (the idle timeout),
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the server is considered to be _inactive (idle)_ and will be culled (shutdown).
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The [idle culler](https://github.com/jupyterhub/jupyterhub-idle-culler) is a JupyterHub service that is installed and enabled by default in TLJH.
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It can be configured using tljh-config. For advanced use-cases, like purging old user data,
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the idle culler configuration can be extended beyond tljh-config options, using custom
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[jupyterhub_config.py snippets](https://tljh.jupyter.org/en/latest/topic/escape-hatch.html?highlight=escape-hatch#extending-jupyterhub-config-py).
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## Default settings
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By default, JupyterHub will ping the user notebook servers every 10 min to check their
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status. Every server found to be idle for more than 1 hour will be culled.
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```python
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services.cull.every = 600
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services.cull.timeout = 3600
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```
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Because the servers don't have a maximum age set, an active server will not be shut down
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regardless of how long it has been up and running.
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```python
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services.cull.max_age = 0
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```
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If after the culling process, there are users with no active notebook servers, by default,
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the users will not be culled alongside their notebooks and will continue to exist.
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```python
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services.cull.users = False
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```
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If named servers are in use, they are not removed after being culled.
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```python
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services.cull.remove_named_servers = False
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```
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## Configuring the idle culler
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The available configuration options are:
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### Idle timeout
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The idle timeout is the maximum time (in seconds) a server can be inactive before it
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will be culled. The timeout can be configured using:
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```bash
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sudo tljh-config set services.cull.timeout <max-idle-sec-before-server-is-culled>
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sudo tljh-config reload
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```
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### Idle check interval
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The idle check interval represents how frequent (in seconds) the Hub will
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check if there are any idle servers to cull. It can be configured using:
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```bash
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sudo tljh-config set services.cull.every <number-of-sec-this-check-is-done>
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sudo tljh-config reload
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```
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### Maximum age
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The maximum age sets the time (in seconds) a server should be running.
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The servers that exceed the maximum age, will be culled even if they are active.
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A maximum age of 0, will deactivate this option.
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The maximum age can be configured using:
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```bash
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sudo tljh-config set services.cull.max_age <server-max-age>
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sudo tljh-config reload
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```
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### Remove Named Servers
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Remove named servers after they are shutdown. Only applies if named servers are
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enabled on the hub installation:
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```bash
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sudo tljh-config set services.cull.remove_named_servers True
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sudo tljh-config reload
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```
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### User culling
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In addition to servers, it is also possible to cull the users. This is usually
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suited for temporary-user cases such as _tmpnb_.
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User culling can be activated using the following command:
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```bash
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sudo tljh-config set services.cull.users True
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sudo tljh-config reload
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```
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### Concurrency
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Deleting a lot of users at the same time can slow down the Hub.
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The number of concurrent requests made to the Hub can be configured using:
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```bash
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sudo tljh-config set services.cull.concurrency <number-of-concurrent-hub-requests>
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sudo tljh-config reload
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```
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Because TLJH it's used for a small number of users, the cases that may require to
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modify the concurrency limit should be rare.
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## Disabling the idle culler
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The idle culling service is enabled by default. To disable it, use the following
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command:
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```bash
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sudo tljh-config set services.cull.enabled False
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sudo tljh-config reload
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```
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