Container running but cannot be visited in browser - docker

Question

I followed http://containertutorials.com/docker-compose/flask-compose.html and have a running container.
$ docker-compose up
Starting flaskcomposedockerexample_web_1
Attaching to flaskcomposedockerexample_web_1
web_1 | * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)
web_1 | * Restarting with stat
web_1 | * Debugger is active!
$ docker logs d66ca374c99a
* Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)
* Restarting with stat
* Debugger is active!
* Debugger PIN: 249-821-232
Going to browser or curl will not connect:
This site can’t be reached
127.0.0.1 refused to connect.
$ curl 127.0.0.1:5000
curl: (7) Failed to connect to 127.0.0.1 port 5000: Connection refused
Why would a container with no errors not be able to be visited?
$ netstat
Active Internet connections
Proto Recv-Q Send-Q Local Address Foreign Address (state)
tcp4 0 0 142.25.150.89.57766 stackoverflow.co.https ESTABLISHED
tcp4 0 0 142.25.150.89.56837 8.36.126.32.http ESTABLISHED
tcp4 0 0 localhost.56800 localhost.56800 ESTABLISHED
tcp4 0 0 localhost.56801 localhost.56801 ESTABLISHED
$ docker inspect d66ca374c99a
[
{
"Id": "d66ca374c99afb13a2bee56fa44fd73f4c39569edcf8c50f175bf5a124a57a73",
"Created": "2017-04-18T14:08:54.859932607Z",
"Path": "python",
"Args": [
"app.py"
],
"State": {
"Status": "running",
"Running": true,
"Paused": false,
"Restarting": false,
"OOMKilled": false,
"Dead": false,
"Pid": 14402,
"ExitCode": 0,
"Error": "",
"StartedAt": "2017-04-18T14:09:28.342011012Z",
"FinishedAt": "0001-01-01T00:00:00Z"
},
"Image": "sha256:1b3ceada8dd91e8a4403e7ee001b7a4832f72120162f8788651c3301f5ccfa89",
"ResolvConfPath": "/mnt/sda1/var/lib/docker/containers/d66ca374c99afb13a2bee56fa44fd73f4c39569edcf8c50f175bf5a124a57a73/resolv.conf",
"HostnamePath": "/mnt/sda1/var/lib/docker/containers/d66ca374c99afb13a2bee56fa44fd73f4c39569edcf8c50f175bf5a124a57a73/hostname",
"HostsPath": "/mnt/sda1/var/lib/docker/containers/d66ca374c99afb13a2bee56fa44fd73f4c39569edcf8c50f175bf5a124a57a73/hosts",
"LogPath": "/mnt/sda1/var/lib/docker/containers/d66ca374c99afb13a2bee56fa44fd73f4c39569edcf8c50f175bf5a124a57a73/d66ca374c99afb13a2bee56fa44fd73f4c39569edcf8c50f175bf5a124a57a73-json.log",
"Name": "/flaskcomposedockerexample_web_1",
"RestartCount": 0,
"Driver": "aufs",
"MountLabel": "",
"ProcessLabel": "",
"AppArmorProfile": "",
"ExecIDs": null,
"HostConfig": {
"Binds": [
"/Users/cchilders/flask_compose_docker_example:/code:rw"
],
"ContainerIDFile": "",
"LogConfig": {
"Type": "json-file",
"Config": {}
},
"NetworkMode": "default",
"PortBindings": {
"5000/tcp": [
{
"HostIp": "",
"HostPort": "5000"
}
]
},
"RestartPolicy": {
"Name": "",
"MaximumRetryCount": 0
},
"AutoRemove": false,
"VolumeDriver": "",
"VolumesFrom": [],
"CapAdd": null,
"CapDrop": null,
"Dns": null,
"DnsOptions": null,
"DnsSearch": null,
"ExtraHosts": null,
"GroupAdd": null,
"IpcMode": "",
"Cgroup": "",
"Links": null,
"OomScoreAdj": 0,
"PidMode": "",
"Privileged": false,
"PublishAllPorts": false,
"ReadonlyRootfs": false,
"SecurityOpt": null,
"UTSMode": "",
"UsernsMode": "",
"ShmSize": 67108864,
"Runtime": "runc",
"ConsoleSize": [
0,
0
],
"Isolation": "",
"CpuShares": 0,
"Memory": 0,
"NanoCpus": 0,
"CgroupParent": "",
"BlkioWeight": 0,
"BlkioWeightDevice": null,
"BlkioDeviceReadBps": null,
"BlkioDeviceWriteBps": null,
"BlkioDeviceReadIOps": null,
"BlkioDeviceWriteIOps": null,
"CpuPeriod": 0,
"CpuQuota": 0,
"CpuRealtimePeriod": 0,
"CpuRealtimeRuntime": 0,
"CpusetCpus": "",
"CpusetMems": "",
"Devices": null,
"DeviceCgroupRules": null,
"DiskQuota": 0,
"KernelMemory": 0,
"MemoryReservation": 0,
"MemorySwap": 0,
"MemorySwappiness": -1,
"OomKillDisable": false,
"PidsLimit": 0,
"Ulimits": null,
"CpuCount": 0,
"CpuPercent": 0,
"IOMaximumIOps": 0,
"IOMaximumBandwidth": 0
},
"GraphDriver": {
"Data": null,
"Name": "aufs"
},
"Mounts": [
{
"Type": "bind",
"Source": "/Users/cchilders/flask_compose_docker_example",
"Destination": "/code",
"Mode": "rw",
"RW": true,
"Propagation": ""
}
],
"Config": {
"Hostname": "d66ca374c99a",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"ExposedPorts": {
"5000/tcp": {}
},
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
"app.py"
],
"ArgsEscaped": true,
"Image": "flaskcomposedockerexample_web",
"Volumes": {
"/code": {}
},
"WorkingDir": "/app",
"Entrypoint": [
"python"
],
"OnBuild": null,
"Labels": {
"com.docker.compose.config-hash": "3c65c28cc5926f591068f82a4d028ae50573b14ac4059ebe17b196be2185995a",
"com.docker.compose.container-number": "1",
"com.docker.compose.oneoff": "False",
"com.docker.compose.project": "flaskcomposedockerexample",
"com.docker.compose.service": "web",
"com.docker.compose.version": "1.11.2"
}
},
"NetworkSettings": {
"Bridge": "",
"SandboxID": "6b4cd91f76cb21f70fc7b1b17e403f21ef790cc1e02fee5547740ac5192229fe",
"HairpinMode": false,
"LinkLocalIPv6Address": "",
"LinkLocalIPv6PrefixLen": 0,
"Ports": {
"5000/tcp": [
{
"HostIp": "0.0.0.0",
"HostPort": "5000"
}
]
},
"SandboxKey": "/var/run/docker/netns/6b4cd91f76cb",
"SecondaryIPAddresses": null,
"SecondaryIPv6Addresses": null,
"EndpointID": "e05d8bf26815734a146d6f4b1fb803b365629dfce732a2b21993970a33e54a80",
"Gateway": "162.16.0.1",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"IPAddress": "162.16.0.4",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"MacAddress": "02:42:bd:55:00:04",
"Networks": {
"bridge": {
"IPAMConfig": null,
"Links": null,
"Aliases": null,
"NetworkID": "2fd3c33ec08105cd00de10ab5555554572bac4548866239aa375e8df60ed3aa",
"EndpointID": "e05d8bf26815734a146d6f4b1fb80555559dfce732a2b21993970a33e54a80",
"Gateway": "162.16.0.1",
"IPAddress": "162.16.0.4",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:44:00:04"
}
}
}
}
]
$ netstat -tnlp
netstat: option requires an argument -- p
Usage: netstat [-AaLlnW] [-f address_family | -p protocol]
netstat [-gilns] [-f address_family]
netstat -i | -I interface [-w wait] [-abdgRtS]
netstat -s [-s] [-f address_family | -p protocol] [-w wait]
netstat -i | -I interface -s [-f address_family | -p protocol]
netstat -m [-m]
netstat -r [-Aaln] [-f address_family]
netstat -rs [-s]
$ netstat -tnpl
netstat: l: unknown or uninstrumented protocol

Answer 1

There are two problems. First the tutorial you are referring to has syntax error in the first line of app.py, it should be
from flask import Flask
Secondly, Docker works differently in Mac and Windows. Docker doesn't directly map the ports to the local host; instead of that Docker creates a very small Linux virtual machine which is approximately 24 mb in size and then run containers inside that this virtual machine which is also called docker machine. So instead of mapping the ports to localhost, Docker maps it to docker machine so your containers should be accessible to
http://docker_machine_ip:port_no
Instead of
http://localhost:port_no
The default docker machine IP address can be found using:
docker-machine ip dev