*`phase`: The default phase is `access`, if not specified. The valid phases are: `rewrite`, `access`,`Header_filer`, `body_filter`, `log` and `balancer`.
*`functions`: A list of functions that are specified to run is an array type, which can contain either one function or multiple functions, executed sequentially.
Note that only function is accepted here, not other types of Lua code. For example, anonymous functions are legal:
```
return function()
ngx.log(ngx.ERR, 'one')
end
```
Closure is also legal:
```
local count = 1
return function()
count = count + 1
ngx.say(count)
end
```
But code that is not a function type is illegal:
```
local count = 1
ngx.say(count)
```
### Example
#### enable plugin
Here's an example, enable the serverless plugin on the specified route:
```shell
curl -i http://127.0.0.1:9080/apisix/admin/routes/1 -X PUT -d '
{
"uri": "/index.html",
"plugins": {
"plugins": {
"serverless-pre-function": {
"phase": "rewrite",
"functions" : ["return function() ngx.log(ngx.ERR, 'serverless pre function'); end"]
}
},
},
"upstream": {
"type": "roundrobin",
"nodes": {
"39.97.63.215:80": 1
}
}
}'
```
#### test plugin
Use curl to access:
```shell
curl -i http://127.0.0.1:9080/index.html
```
Then you will find the message 'serverless pre-function' in the error.log,
which indicates that the specified function is in effect.
#### disable plugin
When you want to disable the serverless plugin, it is very simple,
you can delete the corresponding json configuration in the plugin configuration,
no need to restart the service, it will take effect immediately:
```shell
curl http://127.0.0.1:9080/apisix/admin/routes/1 -X PUT -d '
{
"methods": ["GET"],
"uri": "/index.html",
"upstream": {
"type": "roundrobin",
"nodes": {
"39.97.63.215:80": 1
}
}
}'
```
The serverless plugin has been disabled now. It works for other plugins.
