Questions[json](server)

running aws ec2 describe-instances will return a json text similar to the following:

{
    "Reservations": [
        {
            "Instances": [
                  "PublicDnsName": "ec2..."
                    "VpcId": "vpc-...",
                        ...
            "Instances": [

I know for each "Instance" I can extract the contents of a single field, for example PublicDnsName, using jq as follows: jq '.Reservations[].Instances[].PublicDnsName' which will list the dns names for my instances But how do I extract two or more fields and separate them by a space or comma or something? I want PublicDnsName and VpcId to be listed side-by-side for each Instance.

Specifically what I'm looking for is a list of instances where VpcId is null, undefined, or non-existent. In other words I'd like a list of my Classic instances and I need this through api so I can process the results.

I am getting the following Exception from time to time when my users are connecting with their Android devices to out JSON Rest Service:

java.io.IOException: Socket read failed
       at org.apache.coyote.ajp.AjpProcessor.read(AjpProcessor.java:313)
       at org.apache.coyote.ajp.AjpProcessor.readMessage(AjpProcessor.java:364)
       at org.apache.coyote.ajp.AjpProcessor.receive(AjpProcessor.java:331)
       at org.apache.coyote.ajp.AbstractAjpProcessor.refillReadBuffer(AbstractAjpProcessor.java:614)
       at org.apache.coyote.ajp.AbstractAjpProcessor$SocketInputBuffer.doRead(AbstractAjpProcessor.java:1065)
       at org.apache.coyote.Request.doRead(Request.java:422)
       at org.apache.catalina.connector.InputBuffer.realReadBytes(InputBuffer.java:290)
       at org.apache.tomcat.util.buf.ByteChunk.substract(ByteChunk.java:431)
       at org.apache.catalina.connector.InputBuffer.read(InputBuffer.java:315)
       at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:200)
       at org.codehaus.jackson.impl.ByteSourceBootstrapper.ensureLoaded(ByteSourceBootstrapper.java:340)
       at org.codehaus.jackson.impl.ByteSourceBootstrapper.detectEncoding(ByteSourceBootstrapper.java:137)
       at org.codehaus.jackson.impl.ByteSourceBootstrapper.constructParser(ByteSourceBootstrapper.java:197)
       at org.codehaus.jackson.JsonFactory._createJsonParser(JsonFactory.java:542)
       at org.codehaus.jackson.JsonFactory.createJsonParser(JsonFactory.java:389)
       at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1454)
       at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.readInternal(MappingJacksonHttpMessageConverter.java:124)
       at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:153)
       at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.readWithMessageConverters(HandlerMethodInvoker.java:641)
       at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveRequestBody(HandlerMethodInvoker.java:605)
       at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:354)
       at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171)
       at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:436)
       at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:424)
       at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
       at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
       at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
       at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789)

I am running

• Apache/2.2.20
• mod_jk 1.2.36
• Tomcat 7.0.27

Could this have something to do with a timeout? Like the client closes the connection and the server is not able to read from the socket anymore? Or is it more likely a problem of the server configuration?

UPDATE:

Doing some Apache log awk I found the following Apache log lines corresponding to those Tomcat log exceptions:

192.186.30.116 - - [25/Jun/2012:10:47:14 +0200] "POST /myapp/methodX HTTP/1.1" 400 145 "-" "clientApp BlackBerry9360/7.0.0.530 VendorID/168" 10012655 
192.186.30.120 - - [25/Jun/2012:10:53:13 +0200] "POST /myapp/methodY HTTP/1.1" 400 145 "-" "clientApp BlackBerry9800/6.0.0.668 VendorID/124" 10012164 
192.186.30.116 - - [25/Jun/2012:10:53:36 +0200] "POST /myapp/methodZ HTTP/1.1" 400 145 "-" "clientApp BlackBerry9360/7.0.0.530 VendorID/168" 10012677 
192.82.68.16 - - [25/Jun/2012:11:22:31 +0200] "POST /myapp/methodX HTTP/1.1" 400 145 "-" "clientApp BlackBerry9930/7.1.0.402 VendorID/104" 10012667 
192.82.68.16 - - [25/Jun/2012:11:23:21 +0200] "POST /myapp/methodZ HTTP/1.1" 400 145 "-" "clientApp BlackBerry9930/7.1.0.402 VendorID/104" 10012562 

You can see the status code 400 Bad Request sent to the clients for those requests.

The large numbers at the end of the line (e.g. 10012562) show the time the request was processed on the server in microseconds: 10012562 = about 10 seconds

Looks like the connection is somehow terminated after ten seconds? I looked into the AJP configuration but there is no timeout defined - 10 seconds would be the timeout for async requests which I am not using

I'm trying to figure out how to take all requests made to a particular directory and return a json string without a redirect, in nginx.

Example:

curl -i http://example.com/api/call1/

Expected result:

HTTP/1.1 200 OK
Accept-Ranges: bytes
Content-Type: application/json
Date: Fri, 13 Apr 2012 23:48:21 GMT
Last-Modified: Fri, 13 Apr 2012 22:58:56 GMT
Server: nginx
X-UA-Compatible: IE=Edge,chrome=1
Content-Length: 38
Connection: keep-alive

{"logout": true}

Here's what I have so far in my nginx conf:

location ~ ^/api/(.*)$ {
    index /api_logout.json;
    alias /path/to/file/api_logout.json;
    types { }
    default_type "application/json; charset=utf-8";
    break;
}

However, when I try to make the request the Content-Type doesn't stick:

$ curl -i http://example.com/api/call1/
HTTP/1.1 200 OK
Accept-Ranges: bytes
Content-Type: application/octet-stream
Date: Fri, 13 Apr 2012 23:48:21 GMT
Last-Modified: Fri, 13 Apr 2012 22:58:56 GMT
Server: nginx
X-UA-Compatible: IE=Edge,chrome=1
Content-Length: 38
Connection: keep-alive

{"logout": true}

Is there a better way to do this? How can I get the application/json type to stick?

EDIT: Solution!

I figured out you can just send manual strings in the return statement, so I did that instead of using aliases!

Final code I used:

location /api {
    types { }
    default_type "application/json";
    return 200 "{\"logout\" : true"}";
}

I want rsyslog to write log messages in JSON format, which requires to use double-quotes (") around strings.

Problem is that values sometime include double-quotes themselves, and those need to be escaped - but I can't figure out how to do that.

Currently my rsyslog.conf contains this format that I use (a bit simplified):

$template JsonFormat,"{\"msg\":\"%msg%\",\"app-name\":\"%app-name%\"}\n",sql

But when a msg arrives that contains double quotes, the JSON is broken, example:

user pid=21214 uid=0 auid=4294967295 msg='PAM setcred:
user="oracle" exe="/bin/su" (hostname=?, addr=?, terminal=?
result=Success)'

turns into:

{"msg":"user pid=21214 uid=0 auid=4294967295 msg='PAM setcred:
user="oracle" exe="/bin/su" (hostname=?, addr=?, terminal=?
result=Success)'","app-name":"user"}

but what I need it to become is:

{"msg":"user pid=21214 uid=0 auid=4294967295 msg='PAM setcred:
user=\"oracle\" exe=\"/bin/su\" (hostname=?, addr=?, terminal=?
result=Success)'","app-name":"user"}

I have an nginx server that logs POST $request_body to a file. When I post json to the server, it replaces quotes (") with \x22.

My config looks like this

server {
    server_name myServer;
    listen 8180;
    log_format logMyServer '$request_body';
    location /myServer {
        access_log  /var/log/nginx/request_bodies.log logMyServer;
        proxy_pass http://127.0.0.1:8000/;

        break;
    }
}

Here is how I'm generating the request:

curl -H "Content-Type: application/json" -X POST -d '{"some":{"foo":"bar"}}' localhost:8180/myServer/

My questions are:

• What kind of encoding is \x[number]?
• Is there a way I can configure the logging to include quotes instead of \x22?