A Simple Service

A simple and configurable service that can, for example, be used for testing container orchestration setups (incl. health check endpoint).

Note that the versions of simpleservice, such as 0.4.0, used in the following refer to the tags used in the respective Docker images created. There are no tags or releases as such in this GitHub repo.

Contents:

• The HTTP API
• Running it
• Changing runtime behaviour
• Invoking it

The HTTP API

In addition to the endpoints listed here, see also the change the runtime behaviour section below.

/env [0.5.0+]

Principled response:

HTTP/1.1 200 OK
$HEADER_FIELDS
 {
     "env": "$DUMP_OF_ENVIRONMENT_VARS",
     "version": "$VERSION"
 }

Example response:

HTTP/1.1 200 OK                                                                                                                                                             [5/99]
Content-Length: 2471
Content-Type: application/json
Date: Mon, 24 Apr 2017 12:38:47 GMT
Etag: "5ccb76cf1545f01fd1e0df4257ff6f8da19678e9"
Server: TornadoServer/4.3

{
    "env": "{'USER': 'mhausenblas', ...}"
    "version": "0.5.0"
}    

/info [0.5.0+]

Principled response:

HTTP/1.1 200 OK
$HEADER_FIELDS
 {
     "from": "$REMOTE_IP",
     "host": ""$HOST:$PORT"",
     "version": "$VERSION"
 }

Example response:

HTTP/1.1 200 OK
Content-Length: 67
Content-Type: application/json
Date: Mon, 24 Apr 2017 12:36:37 GMT
Etag: "9d09b0a126f68a0fddfec0f494e56fcab29eac15"
Server: TornadoServer/4.3

{
    "from": "127.0.0.1",
    "host": "localhost:9876",
    "version": "0.5.0"
}

/health [0.4.0+]

Principled response:

HTTP/1.1 200 OK
$HEADER_FIELDS
 {
     "healthy": true
 }

Example response:

HTTP/1.1 200 OK
Content-Length: 17
Content-Type: application/json
Date: Tue, 11 Oct 2016 17:17:21 GMT
Etag: "b40026a9bea9f5096f4ef55d3d23d6730139ff5e"
Server: TornadoServer/4.3

{
    "healthy": true
}

/endpoint0 [0.3.0+]

Principled response:

HTTP/1.1 200 OK
$HEADER_FIELDS
{
    "host": "$HOST:$PORT",
    "result": "all is well",
    "version": "$VERSION"
}

Example response:

HTTP/1.1 200 OK
Content-Length: 71
Content-Type: application/json
Date: Tue, 11 Oct 2016 16:57:33 GMT
Etag: "ce18606c019e1d8c584b796d1fe7402d9767b9b6"
Server: TornadoServer/4.3

{
    "host": "localhost:9876",
    "result": "all is well",
    "version": "0.4.0"
}

Running it

For local execution, Python 2.7.9 is required. You can then run simpleservice like so:

# with defaults:
$ python simpleservice.py

# overwriting certain runtime settings:
$ HEALTH_MAX=200 VERSION=1.0 python simpleservice.py

If you fancy it you can run the containerized version of simpleservice on your local machine (requires Docker installed):

$ docker run -P mhausenblas/simpleservice:0.5.0

See also the container images.

Changing runtime behaviour

Through setting the following environment variables, you can change the runtime behaviour of simpleservice:

• PORT0 ... the port simpleservice is serving on
• VERSION ... the value of version returned in the JSON response of the /endpoint0 endpoint
• HEALTH_MIN and HEALTH_MAX ... the min. and max. delay in milliseconds that the /health endpoint responds

Invoking it

Once simpleservice is started you can invoke it like so (here is a local service execution shown):

$ http localhost:9876/endpoint0
HTTP/1.1 200 OK
Content-Length: 71
Content-Type: application/json
Date: Tue, 11 Oct 2016 16:57:33 GMT
Etag: "ce18606c019e1d8c584b796d1fe7402d9767b9b6"
Server: TornadoServer/4.3

{
    "host": "localhost:9876",
    "result": "all is well",
    "version": "0.4.0"
}

And the service logs would show something like:

~$ python simpleservice.py
This is a simple service in version v0.4.0 listening on port 9876
2016-10-11T05:57:33 INFO /endpoint0 serving from localhost:9876 has been invoked from 127.0.0.1 [at line 58]
2016-10-11T05:57:33 INFO 200 GET /endpoint0 (127.0.0.1) 1.10ms [at line 1946]

Note that the available endpoints depend on the version of simpleservice as defined in the first section of this docs (aka API).