Skip to content

Latest commit

 

History

History
114 lines (99 loc) · 5.11 KB

running.md

File metadata and controls

114 lines (99 loc) · 5.11 KB
Raw

Running the CRT Application

To run the application, it must be built and installed on a target system. For our purposes, the current execution environment is a Docker container. Specifically, the Docker container used as the reproducible build context in the Building the CRT Application guide.

  • Coming Soon: running the application as a Kubernetes Deployment

Help

The application has a help option (-h) to get you started. Most of the basics are covered in this context.

root@eb878eedb396:/usr/src/src# /usr/local/crt/bin/crt -h
NAME
	C++ REST Template (crt) Application 

SYNOPSIS:
	crt [OPTIONS]

OPTIONS:
	-d	enable the controller to run as a daemon process, default: disabled
	-r	enable the HTTP REST interface, default: disabled
	-p <port number>
		specify the port for the HTTP REST API server to listen on, default: 8092
	-l <logging level>
		set the desired level of log file output, default: notice
		the value specified for logging level may only be one of the following values:
		  fatal       - errors that cause the system to exit
		  critical    - errors that cause unexpected/unpredictable system behavior
		  error       - errors that are handled and allow the system to continue operating
		  warning     - indication of a condition that merit ongoing monitoring
		  notice      - general system condition notification, e.g. timer expiry
		  information - general operational output
		  debug       - verbose output for system troubleshooting
		  trace       - extremely verbose output for full system diagnostics

Basic Execution

To simply run the CRT Application execute the command:

root@eb878eedb396:/usr/src/src# /usr/local/crt/bin/crt -d -r

That's it. What's actually taken place here is that the crt application started up as a Linux daemon (-d) process, and is running the REST API Service (-r).

We can see this as follows:

root@eb878eedb396:/usr/src/src# ps -eaf
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 19:35 pts/0    00:00:00 bash
root       182     1  0 20:01 ?        00:00:00 /usr/local/crt/bin/crt -d -r

Logging

In the previous example the application was run with the default logging level: notice. As such, there weren't any events to see in the CRT log file.

Restart the application (after terminating the old one to avoid a port collision), with the logging level set to debug.

root@eb878eedb396:/usr/src/src# /usr/local/crt/bin/crt -d -r -l debug

Now inspect the logfile to view the debugging information output.

root@eb878eedb396:/usr/src/src# cat /var/log/crt/crt.log 
# Log file created/rotated Tuesday, 27 Feb 18 20:12:44 GMT
02-27-2018 20:12:44.238 | 199:0 | Information(6) | crt.cpp:575 | main(): REST API Initialized. |
02-27-2018 20:12:44.238 | 199:0 | Information(6) | crt.cpp:578 | main(): successful initialization, entering main event loop. |

Query the REST API

Now that the service is running in the background as a daemon process, and listening on the default port, we can begin querying the service. The debug logging remains enabled to show additional output. As noted in the Help section above, the default port is 8092.

Query the root endpoint (/) on the default port.

root@eb878eedb396:/usr/src/src# curl http://127.0.0.1:8092/                      
{
	"endpoints": [{
		"urn": "/v1",
		"supported_methods": ["GET"]
	}, {
		"urn": "/versions",
		"supported_methods": ["GET"]
	}, {
		"urn": "/health",
		"supported_methods": ["GET"]
	}]
}

Note: the returned JSON body has been externally formatted for readability (steps not shown).

Query the unversioned health check endpoint (/health).

root@eb878eedb396:/usr/src/src# curl http://127.0.0.1:8092/health
{ "type": "liveness" }

Query a versioned endpoint... etc... more to come when they're working...

Shutting Down

The daemon process gracefully handles shutdown requests from the Linux kill command.

root@eb878eedb396:/usr/src/src# ps aux | grep crt
root       199  0.0  0.4 276212  9136 ?        Sl   20:12   0:01 /usr/local/crt/bin/crt -d -r -l debug

root@eb878eedb396:/usr/src/src# kill 199

Logged Output

From the series of queries shown above, the following logging output is captured.

# cat /var/log/crt/crt.log 
# Log file created/rotated Tuesday, 27 Feb 18 20:12:44 GMT
02-27-2018 20:12:44.238 | 199:0 | Information(6) | crt.cpp:575 | main(): REST API Initialized. |
02-27-2018 20:12:44.238 | 199:0 | Information(6) | crt.cpp:578 | main(): successful initialization, entering main event loop. |
02-27-2018 20:21:15.040 | 199:2 | Information(6) | Router.cpp:87 | createRequestHandler(): request method: GET, URI: /, Query:  |
02-27-2018 20:25:39.251 | 199:2 | Information(6) | Router.cpp:87 | createRequestHandler(): request method: GET, URI: /health, Query:  |
02-27-2018 20:25:39.251 | 199:2 | Debug(7) | MonitorEndpoint.cpp:46 | MonitorEndpoint::handleRequest()) |
02-27-2018 20:34:36.943 | 199:0 | Information(6) | crt.cpp:125 | ::controller(): signaled quit/shutdown. |
02-27-2018 20:34:37.183 | 199:0 | Information(6) | crt.cpp:590 | main(): exiting. |