Access IP address of Couchbase container on Docker Swarm cluster

Question

Trying to run a Couchbase cluster on Docker Swarm cluster. After the cluster is started, I'd like to obtain the IP address of each Couchbase instance dynamically. docker inspect shows:

"NetworkSettings": {
        "Bridge": "",
        "SandboxID": "325807d55b552be3fe5b44b4d975c2486b3a56b320aa56fa0367e42348b82d64",
        "HairpinMode": false,
        "LinkLocalIPv6Address": "",
        "LinkLocalIPv6PrefixLen": 0,
        "Ports": {
            "11207/tcp": null,
            "11210/tcp": [
                {
                    "HostIp": "192.168.99.101",
                    "HostPort": "11210"
                }
            ],

Trying to access the IP address gives the error:

docker inspect --format '{{ .NetworkSettings.Ports.8091/tcp[0].HostIp }}' 922755302fef
Template parsing error: template: :1: unexpected ".8091" in operand; missing space?

What is the right format to access the IP address?

score 1 · Accepted Answer · edited May 23 '17 at 12:31

The property .NetworkSettings.Ports is a map, not a struct. You can use the index template function to access the map (and also slice) values:

$ docker inspect --format '{{ index .NetworkSettings.Ports "8091/tcp" 0 "HostIp" }}'

Note however, that this may not always return what you expect. If the container is configured to listen on all host interfaces, this will simply return 0.0.0.0. You could have a look at the networking feature that was introduced with Docker 1.9 for this without relying on looking up host IP addresses.

Access IP address of Couchbase container on Docker Swarm cluster

1 Answers1