Imagine Traefik is a very polite restaurant that's about to close for the night. It doesn't want to abruptly kick everyone out while they're still eating. The lifeCycle options help it manage this closing process gracefully.
lifeCycle.requestAcceptGraceTimeout: Letting New Customers Know We're Closing Soon
This is like the restaurant putting up a "Last Orders" sign for a certain period before it actually starts asking people to leave.
What it does: For the duration you set in requestAcceptGraceTimeout, Traefik will still accept new requests coming in. This is important because if you have other traffic managers (like load balancers) sending traffic to Traefik, this gives them time to realize Traefik is going down and stop sending new customers.
Why it's useful: It prevents new requests from being immediately dropped when Traefik starts its shutdown process. It gives your other systems a chance to adjust and send new traffic elsewhere.
Default: If you don't set it (or set it to 0s), Traefik will immediately stop accepting new requests when the shutdown process begins.
Concrete Example (requestAcceptGraceTimeout: 5s):
Let's say you tell Traefik to shut down. If requestAcceptGraceTimeout is set to 5s, Traefik will:
For the first 5 seconds after receiving the shutdown signal, it will still accept new incoming requests.
During this time, hopefully, your load balancers will notice Traefik is going down and stop sending it new traffic.
After these 5 seconds are up, Traefik will stop accepting any new requests and move to the next phase (graceTimeOut).
lifeCycle.graceTimeOut: Giving Current Customers Time to Finish Their Meals
This is like the restaurant saying, "Okay, no more new orders, but if you're already eating, please take your time to finish."
What it does: This option sets a time limit for how long Traefik will wait for active, ongoing requests to complete before it forcefully shuts down.
Why it's useful: It prevents Traefik from abruptly cutting off connections while a user is in the middle of downloading a file, submitting a form, or any other ongoing interaction with your application. This leads to a much smoother user experience during shutdowns.
Default: If you don't set it, it defaults to 10s.
Time Format: You can specify the duration in formats like 30s (30 seconds), 1m (1 minute), 2h30m (2 hours and 30 minutes), or just a number which will be interpreted as seconds (e.g., 60 means 60 seconds).
Concrete Example (graceTimeOut: 30s):
Let's say after the requestAcceptGraceTimeout (if set) expires, Traefik has some active requests still being processed. If graceTimeOut is set to 30s, Traefik will:
Wait for up to 30 seconds for these ongoing requests to finish their work.
If a request finishes within this 30-second window, Traefik will let it complete normally.
If a request is still running after 30 seconds, Traefik will forcefully terminate it and then shut down.
Putting it all together (Restaurant Closing Analogy)
Imagine the restaurant wants to close at 10:00 PM.
At 9:55 PM (requestAcceptGraceTimeout: 5m), the waiter starts telling new customers, "Sorry, last orders!" but still takes their orders.
At 10:00 PM, the waiter stops taking new orders.
From 10:00 PM to 10:10 PM (graceTimeOut: 10m), the restaurant allows the customers who are already eating to finish their meals.
At 10:10 PM, the lights go out, and anyone still eating is politely (or maybe not so politely) asked to leave.
In the Traefik world, these lifeCycle options ensure a more graceful shutdown, giving time for other systems to adjust and for ongoing user interactions to complete, leading to less disruption.
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