Loading new yaws configuration file while running yaws

Question

I am using YAWS to serve my remote application. When ever there is a change in yaws.conf file i am restarting the server to make these changes in effect. I don't want to do this, because my application might crash if server is down for more than certain time.

So is there a way to load the new configuration file with out stopping the server, like live code update?

In case you also need to reload your appmod modules, you might find the following command useful: `$ yaws --load your_appmod_module1 your_appmod_module2` — Ning, Aug 17 '13 at 07:34

score 8 · Accepted Answer · answered Aug 16 '13 at 21:05

8

You can use the following command from an interactive shell to reload the Yaws config file without restarting the server:

yaws --hup --id ID

where the --id ID portion is optional — if you're running multiple Yaws instances, it lets you identify which particular Yaws server you want to reload.

answered Aug 16 '13 at 21:05

Steve Vinoski

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Of course, "--hup" - what an obvious name for that option. ;-) – RichardC Aug 17 '13 at 10:51
Not totally obvious, I agree. The option is named after SIGHUP, which is traditionally sent to force UNIX daemons to re-read their configurations. The option is also explained if you run `yaws --help`. – Steve Vinoski Aug 20 '13 at 13:47
Hah. This actually *is* an obvious name, so obvious I wouldn't have guessed it (like when looking high and low for a "run" command and it turns out to be called... "run"). Now I'll never forget that. – zxq9 Dec 01 '14 at 08:37

score 1 · Answer 2 · answered Aug 16 '13 at 19:14

There's yaws_api:setconf(GC, SCList), mostly intended for running Yaws "embedded" (i.e., under one of your own supervisors instead of starting Yaws as a separate application). But when you do that, Yaws will still tear down all existing ports and connections in order to set up the new configuration. So the first question is: have you measured the time it takes to restart the whole Yaws application? It might be only slightly slower than reloading the configuration, in which case you would make your code more complicated without really gaining anything.

Loading new yaws configuration file while running yaws

2 Answers2