Docker container port 80 - "Connection refused"

Question

Docker file content -

[root@ansiblecontrolnode dockerbuild]# cat Dockerfile

FROM centos:latest
MAINTAINER [email protected]
RUN yum update -y && yum install httpd net-tools -y
CMD ["apachectl","-D","FOREGROUND"]
EXPOSE 80

Ansible playbook - To create a new docker image -

[root@ansiblecontrolnode dockerbuild]# cat build_docker_image.yml
---
        - name: Build a docker image
          hosts: localhost
          gather_facts: no
          tasks:
                - name: Build a CENTOS (latest) docker image with fully updated and Webservice installed
                  docker_image:
                        path: /root/ANSIBLE/ANSIBLEDOCKER/dockerbuild/
                        name: docker-image-created-by-ansible
                        tag: ansibleexample
...

Checking syntax

[root@ansiblecontrolnode dockerbuild]# ansible-playbook 
build_docker_image.yml --syntax-check

playbook: build_docker_image.yml

Building Docker image using ansible with http installed -

[root@ansiblecontrolnode dockerbuild]# ansible-playbook build_docker_image.yml

Post build - checking images

[root@ansiblecontrolnode dockerbuild]# docker images

REPOSITORY                        TAG                 IMAGE ID            CREATED             SIZE
docker-image-created-by-ansible   ansibleexample      622e72211b67        35 minutes ago      449MB
centos                            latest              e934aafc2206        6 weeks ago         199MB

Spinning-up 1st container from 622e72211b67 image -

[root@ansiblecontrolnode dockerbuild]# docker run -it --name httpimage 622e72211b67 bash

Container run status (with port 80 exposed) -

[root@ansiblecontrolnode dockerbuild]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
be452b97dda0        622e72211b67        "bash"              7 minutes ago       Up 7 minutes        80/tcp              httpimage

Getting container IP address -

[root@ansiblecontrolnode dockerbuild]# docker inspect --format '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}'  httpimage
172.17.0.2

[root@ansiblecontrolnode dockerbuild]# ping -c2 172.17.0.2

PING 172.17.0.2 (172.17.0.2) 56(84) bytes of data.
64 bytes from 172.17.0.2: icmp_seq=1 ttl=64 time=0.107 ms
64 bytes from 172.17.0.2: icmp_seq=2 ttl=64 time=0.058 ms

--- 172.17.0.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.058/0.082/0.107/0.026 ms

[root@ansiblecontrolnode dockerbuild]# telnet 172.17.0.2 80
Trying 172.17.0.2...

telnet: connect to address 172.17.0.2: Connection refused

[root@ansiblecontrolnode dockerbuild]# curl http://172.17.0.2:80

curl: (7) Failed connect to 172.17.0.2:80; Connection refused

Please suggest what is wrong here?

Thanks, Dhirendra

Answer 1

Notice the difference between your first output of docker ps:

[root@ansiblecontrolnode dockerbuild]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
be452b97dda0        622e72211b67        "bash"              7 minutes ago       Up 7 minutes        80/tcp              httpimage

And your second output of the same command:

[root@ansiblecontrolnode dockerbuild]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
bfe98153a77a        0f104cab653d        "apachectl -D FOREGR…"   41 seconds ago      Up 40 seconds       80/tcp              httpcontainer

On you first attempt you were starting the container with this command:

docker run -it --name httpimage 622e72211b67 bash

On the second you were using this command:

docker run -tid --name httpcontainer 0f104cab653d

The result: On the first run you were starting bash instead of apache. The container was running, but apache wasn't running, so you got Connection refused when you tried to access it with curl.