Actions are used with the
return(<action>) keyword, which returns
control from subroutines back to varnish. The action determines how
processing in varnish continues as shown in Varnish Processing States.
Common actions are documented here, while additional actions specific to only one or some subroutines are documented in Built-in subroutines as well as which action can be used from which built in subroutine.
common actions for the client and backend side¶
Transition to vcl_synth on the client side as for
return(synth(503, "VCL Failed")), but with any request state changes undone as if
std.rollback()was called and forcing a connection close.
Intended for fatal errors, for which only minimal error handling is possible.
common actions for the client side¶
synth(status code, reason)¶
Transition to vcl_synth with
resp.reasonbeing preset to the arguments of
Switch to pass mode, making the current request not use the cache and not putting its response into it. Control will eventually pass to vcl_pass.
Switch to pipe mode. Control will eventually pass to vcl_pipe.
Restart the transaction. Increases the
If the number of restarts is higher than the max_restarts parameter, control is passed to vcl_synth as for
return(synth(503, "Too many restarts"))
For a restart, all modifications to
reqattributes are preserved except for
req.xid, which need to change by design.
common actions for the backend side¶
Abandon the backend request. Unless the backend request was a background fetch, control is passed to vcl_synth on the client side with
resp.statuspreset to 503.