RFR: bot: modularize HTTP server

[Erik Helin]

Hi all,

please review this patch that modularizes the bot HTTP server. The HTTP server featured by the bot runner is currently only used to process webhooks, but I have coming patches that extends it with other functionality. This refactoring make the bot runner start the actual server and then handlers can be configured in a configuration file. A minimal configuration file looks like:


{
    "scratch": {
        "path": "/tmp/skara/scratch"
    },
    "storage": {
        "path": "/tmp/skara/storage"
    },
    "runner": {
        "interval": "PT10S",
        "watchdog": "PT30M",
        "concurrency": 2
    },
    "log": {
        "console": {
            "level": "FINER"
        }
    },
    "http-server": {
        "port": 8080,
        "/api": {
            "type": "webhook"
        }
   }
}


Using the above configuration stored in `config.json` the bot runner can then be started as:


$ make bots
$ ./bots/bin/bin/skara-bots $PWD/config.json


The HTTP server can be then be queried using e.g. `curl`:


$ curl --verbose --request POST --data '{"foo": "bar"}'  http://localhost:8080/api
Note: Unnecessary use of -X or --request, POST is already inferred.
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0*   Trying 127.0.0.1:8080...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8080 (#0)
> POST /api HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.68.0
> Accept: */*
> Content-Length: 14
> Content-Type: application/x-www-form-urlencoded
>
} [14 bytes data]
* upload completely sent off: 14 out of 14 bytes
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Wed, 12 May 2021 07:18:50 GMT
< Content-length: 2
<
{ [2 bytes data]
100    16  100     2  100    14     66    466 --:--:-- --:--:-- --:--:--   533
* Connection #0 to host localhost left intact
{}


I also updated the webhook handler to return `404` if the supplied data cannot be parsed as valid JSON.

Testing:
- [x] Tested manually on Linux x64

Thanks,
Erik

-------------

Commit messages:
 - bot: modularize HTTP server

Changes: https://git.openjdk.java.net/skara/pull/1149/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1149&range=00
  Stats: 128 lines in 3 files changed: 80 ins; 16 del; 32 mod
  Patch: https://git.openjdk.java.net/skara/pull/1149.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1149/head:pull/1149

PR: https://git.openjdk.java.net/skara/pull/1149