How to access a port exposed from a docker container? - linux

Question

$ docker container ls --format "table {{.ID}}\t{{.Names}}\t{{.Ports}}" -a
CONTAINER ID NAMES PORTS
ae87d83af7d3 hopeful_engelbart
d13e260c4dec unruffled_bouman
db2c482de210 jenkinsci 0.0.0.0:8080->8080/tcp, 50000/tcp
cd201cbd413e xyz 0.0.0.0:5000->5000/tcp
c64c32ac68b8 pqr
$ docker container ls -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ae87d83af7d3 442c97a73937 "/bin/bash" 11 minutes ago Exited (0) 9 minutes ago hopeful_engelbart
d13e260c4dec 442c97a73937 "/bin/bash" 27 minutes ago Exited (0) 24 minutes ago unruffled_bouman
db2c482de210 jenkins/jenkins:lts "/sbin/tini -- /usr/…" 3 days ago Up 41 minutes 0.0.0.0:8080->8080/tcp, 50000/tcp jenkinsci
cd201cbd413e 442c97a73937 "bash" 3 days ago Up 7 minutes 0.0.0.0:5000->5000/tcp xyz
c64c32ac68b8 442c97a73937 "bash" 3 days ago Exited (0) 2 days ago pqr
Above outputs show that the port 5000 has been exposed (I hope).
docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' xyz
172.17.0.3
Now when I do from the host machine:
wget -c 172.17.0.3:5000
--2019-12-30 16:26:44-- http://172.17.0.3:5000/
Connecting to 172.17.0.3:5000... failed: Connection refused.
What is the way to access that port since it is exposed and the container is running?
$ wget -c localhost:5000
--2019-12-30 16:41:57-- http://localhost:5000/
Resolving localhost (localhost)... 127.0.0.1
Connecting to localhost (localhost)|127.0.0.1|:5000... connected.
HTTP request sent, awaiting response... Read error (Connection reset by peer) in headers.
Retrying.
--2019-12-30 16:41:58-- (try: 2) http://localhost:5000/
Connecting to localhost (localhost)|127.0.0.1|:5000... connected.
HTTP request sent, awaiting response... Read error (Connection reset by peer) in headers.
Retrying.

Answer 1

First of all, check if you have an application, listening to the port inside your container. Just try to connect to it from your container:
docker exec xyz wget 127.0.0.1:5000
If it'll work then you have a problem with port exposing, otherwise, there is no web server running inside your container.
And the error you get
Read error (Connection reset by peer) in headers.
seems to point to the problem in your web server rather then connectivity issues.

Answer 2

I had this problem running one Quarkus application with Docker.
I found this topic on forum.dockers talking about a similar issue.
In this topic is said:
I was using flask, by default it binds to localhost & 5000, so you have to specify:
app.run(host=“0.0.0.0”)
So, in my case I guess the problem was on my application and not on Docker network.
I added this property on the Java command to start my application on my Dockerfile and everything worked fine:
-Dquarkus.http.host=0.0.0.0