10.7. Communicating between containers using port mapping

Procedure

1. Run the unpublished container:

   # podman run -dt --name=web1 ubi10/httpd-24

2. Run the automatically published container:

   # podman run -dt --name=web2 -P ubi10/httpd-24

3. Run the manually published container and publish container port 8080:

   # podman run -dt --name=web3 -p 8888:8080 ubi10/httpd-24

4. List all containers:

   # podman ps
   
   CONTAINER ID  IMAGE                                            COMMAND               CREATED         STATUS         PORTS                                             NAMES
   db23e8dabc74  registry.access.redhat.com/ubi10/httpd-24:latest  /usr/bin/run-http...  23 seconds ago  Up 23 seconds  8080/tcp, 8443/tcp                                web1
   1824b8f0a64b  registry.access.redhat.com/ubi10/httpd-24:latest  /usr/bin/run-http...  18 seconds ago  Up 18 seconds  0.0.0.0:33127->8080/tcp, 0.0.0.0:37679->8443/tcp  web2
   39de784d917a  registry.access.redhat.com/ubi10/httpd-24:latest  /usr/bin/run-http...  5 seconds ago  Up 5 seconds  0.0.0.0:8888->8080/tcp, 8443/tcp                  web3

   You can see that:

   • Container web1 has no published ports and can be reached only by container network or a bridge.

   • Container web2 has automatically mapped ports 43595 and 42423 to publish the application ports 8080 and 8443, respectively.

     注意

     The automatic port mapping is possible because the registry.access.redhat.com/10/httpd-24 image has the EXPOSE 8080 and EXPOSE 8443 commands in the Containerfile.

   • Container web3 has a manually published port. The host port 8888 is mapped to the container port 8080.

5. Display the IP addresses of web1 and web3 containers:

   # podman inspect --format='{{.NetworkSettings.IPAddress}}' web1
   # podman inspect --format='{{.NetworkSettings.IPAddress}}' web3

6. Reach web1 container using <IP>:<port> notation:

   # curl 10.88.0.2:8080
   ...
   <title>Test Page for the HTTP Server on Red Hat Enterprise Linux</title>
   ...

7. Reach web2 container using localhost:<port> notation:

   # curl localhost:43595
   ...
   <title>Test Page for the HTTP Server on Red Hat Enterprise Linux</title>
   ...

8. Reach web3 container using <IP>:<port> notation:

   # curl 10.88.0.4:8080
   ...
   <title>Test Page for the HTTP Server on Red Hat Enterprise Linux</title>
   ...