gocql + docker“未找到”

Question

I have a docker compose file set up like this:

version: "3"
services:
  web:
    image: myApp
    container_name: web
    environment:
      CASSANDRA_HOSTS: "db"
    ports:
      - "8080:8080"
    restart: unless-stopped
    depends_on:
      - cassandra
    links:
      - cassandra:db
  cassandra:
    image: cassandra
    restart: unless-stopped
    ports:
      - "9042:9042"
    expose:
      - "9042"
      - "7000"
      - "7001"
      - "9160"
    volumes:
      - "/private/cassandra_docker/:/var/lib/cassandra"

and when start the services up with docker-compose up -d 'web' logs:

2018/11/04 13:01:33 gocql: unable to create session: control: unable to connect to initial hosts: dial tcp 172.19.0.2:9042: connect: connection refused
2018/11/04 13:01:39 gocql: unable to dial control conn 172.19.0.2: dial tcp 172.19.0.2:9042: connect: connection refused
2018/11/04 13:01:39 could not open session with cassandra
2018/11/04 13:01:39 gocql: unable to create session: control: unable to connect to initial hosts: dial tcp 172.19.0.2:9042: connect: connection refused
2018/11/04 13:01:53 gocql: Session.handleNodeUp: 172.19.0.2:9042
2018/11/04 13:01:53 not found
2018/11/04 13:02:19 gocql: Session.handleNodeUp: 172.19.0.2:9042
2018/11/04 13:02:19 not found

when i then use docker inspect docker_cassandra_1 i see it having this ip address - so resolution works fine:

 "Networks": {
                "docker_default": {
                    "IPAMConfig": null,
                    "Links": null,
                    "Aliases": [
                        "101ae9d068ce",
                        "cassandra"
                    ],
                    "NetworkID": "9b416bdf21c152a7d751c264b9f42799534800f08b17ada6d90ee92d62c390bc",
                    "EndpointID": "bc2fe3cc3fb9967e0e056d24a98b97afbc856d54f7695f8e7cfb2583a397285a",
                    "Gateway": "172.19.0.1",
                    "IPAddress": "172.19.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "02:42:ac:13:00:02"
                }
            }

and in the logs of cassandra i see that the node knows what it's ip address is, and it is listening on the correct port too:

10:06:37,709 StorageService.java:2289 - Node /172.19.0.2 state jump to NORMAL cassandra_1 INFO [main] 2018-11-04 10:06:37,737 Gossiper.java:1692 - Waiting for gossip to settle... cassandra_1 INFO [main] 2018-11-04 10:06:45,745 Gossiper.java:1723 - No gossip backlog; proceeding cassandra_1 INFO [main] 2018-11-04 10:06:46,379 NativeTransportService.java:70 - Netty using native Epoll event loop cassandra_1 | INFO [main] 2018-11-04 10:06:46,496 ... Starting listening for CQL clients on /0.0.0.0:9042 (unencrypted)...

when docker inspect web i see that it has no IP Address and is stuck restarting (and cannot be stopped except by force removing the image:

"Networks": {
                "docker_default": {
                    "IPAMConfig": null,
                    "Links": [
                        "docker_cassandra_1_9415bd9be111:cassandra_1_9415bd9be111",
                        "docker_cassandra_1_9415bd9be111:db",
                        "docker_cassandra_1_9415bd9be111:docker_cassandra_1_9415bd9be111"
                    ],
                    "Aliases": [
                        "82f1f884ee5f",
                        "web"
                    ],
                    "NetworkID": "9b416bdf21c152a7d751c264b9f42799534800f08b17ada6d90ee92d62c390bc",
                    "EndpointID": "",
                    "Gateway": "",
                    "IPAddress": "",
                    "IPPrefixLen": 0,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "",
                    "DriverOpts": null
                }
            }

docker ps:

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                         PORTS                                                       NAMES
82f1f884ee5f        myApp               "/bin/bash -c '/runA…"   6 minutes ago       Restarting (1) 5 minutes ago                                                               web
b3713664e748        cassandra           "docker-entrypoint.s…"   6 minutes ago       Up 6 minutes                   7000-7001/tcp, 7199/tcp, 9160/tcp, 0.0.0.0:9042->9042/tcp   docker_cassandra_1

I also checked the system.local table in cassandra - all addresses are the correct one (the one docker dns resolves to)

what is the problem here?

EDIT.:

failed to mention: docker exec -it docker_cassandra_1 cqlsh lets me connect to the database - so it is obviously up

EDIT2:

i did some further testing and installed nmap on the myApp container (and changed it to run /bin/bash on startup instead of my entrypoint script)

this is run on the "web" container

Starting Nmap 7.60 ( https://nmap.org ) at 2018-11-04 14:13 UTC
Nmap scan report for db (172.19.0.2)
Host is up (0.000061s latency).
rDNS record for 172.19.0.2: docker_cassandra_1.docker_default

PORT     STATE SERVICE
9042/tcp open  unknown
MAC Address: 02:42:AC:13:00:02 (Unknown)

Nmap done: 1 IP address (1 host up) scanned in 0.47 seconds
root@028dcea32e53:/run.sh 
2018/11/04 14:14:01 gocql: Session.handleNodeUp: 172.19.0.2:9042
2018/11/04 14:14:01 not found

docker exec -it docker_cassandra_1 /bin/bash

lets me connect via the external IP

csqlsh 172.19.0.2
Connected to Test Cluster at 172.19.0.2:9042.
[cqlsh 5.0.1 | Cassandra 3.11.3 | CQL spec 3.4.4 | Native protocol v4]

This is the code I connect with:

cluster := gocql.NewCluster("db")
    cluster.Keyspace = "myApp"
    cluster.ProtoVersion = 4
    cluster.Consistency = gocql.One
    var err error
    DataSource.Client, err = cluster.CreateSession()

edit:

it also does not work when i start my app on the hosts and try to connect to 127.0.0.1, while port 9042 is exposed via -p 9042:9042

Answer 1

Open your terminal and first verify the port is already is use or not using the following command

sudo lsof -i :9042

if It is already used the you will get a list containing the process ID. You can kill the operation by using the following command

sudo kill <process ID>

After this check all the actively running docker containers by using the following command

docker ps -a

Now we can remove all the docker containers using the following command

docker rm -f $(docker ps -aq)

After all these operation use the docker compose up command that you used in your project.

docker-compose up -d

Hope it will work!