error: Unable to create API: API creation failure: Unable to obtain API(s) from the API Gateway: "connect EHOSTUNREACH 172.20.189.80:9000"

Hi, trying to get this thing up and running via docker-compose for the first time. Spent a few hours and nothing works.

```
Installing apimgmt actions
ok: updated action apimgmt/getApi
ok: updated action apimgmt/createApi
ok: updated action apimgmt/deleteApi
waiting for the Whisk invoker to come up ...
... OK
creating the hello.js function ...
invoking the hello-world function ...
adding the function to whisk ...
ok: created action hello
invoking the function ...
invocation result: { "payload": "Hello, World!" }
{ "payload": "Hello, World!" }
creating an API from the hello function ...
ok: updated action hello
error: Unable to create API: API creation failure: Unable to obtain API(s) from the API Gateway: "connect EHOSTUNREACH 172.20.189.80:9000"
invoking:
curl: no URL specified!
curl: try 'curl --help' or 'curl --manual' for more information
Error invoking the web action
==> /root/tmp/openwhisk/invoker/logs/invoker-local_logs.log <==
...
make: *** [Makefile:417: hello-world] Error 1
```

I try `make destroy` then `make quick-start` but the same error.

I try `make docker-pull` and `make docker-build`, and then `docker-compose ps` to check the dockers. After that I run `make run` and `make hello-world` but the same error.

```bash
docker ps | grep whisk | grep 9000
```

```
37470161e446 openwhisk/apigateway:nightly "/usr/bin/dumb-init …" 5 minutes ago Up 5 minutes 0.0.0.0:80->80/tcp, 0.0.0.0:443->443/tcp, 0.0.0.0:9000->9000/tcp, 8423/tcp, 0.0.0.0:9090->8080/tcp openwhisk_apigateway_1
f8ea5e51b880 minio/minio:RELEASE.2018-07-13T00-09-07Z "/usr/bin/docker-ent…" 6 minutes ago Up 6 minutes (healthy) 0.0.0.0:9001->9000/tcp openwhisk_minio_1
```

```
http://172.20.189.80:9000/
```

```
404 Not Found
openresty/1.17.8.2
```

Iniziare da Makefile:417 e dalla configurazione docker-compose di API Gateway e invoker; esaminare /root/tmp/openwhisk/invoker/logs/invoker-local_logs.log insieme all'indirizzo EHOSTUNREACH segnalato. Riprodurre il problema con make run e make hello-world, quindi seguire la creazione dell'API fino a quando l'esempio hello-world viene completato senza l'errore di connessione al gateway.

Scritto dal modello di indicizzazione a partire dal testo della issue.