Could not resolve host: gogs-repo

问题

I have a running container:

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
3825fa57b1ae        repo:0.1.0          "/app/gogs/docker/st…"   29 minutes ago      Up 29 minutes       22/tcp, 3000/tcp    gogs-repo

and tried to curl it from another container as follows:

docker run --rm curlimages/curl:7.69.1 -L -v http://gogs-repo:3000
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0* Could not resolve host: gogs-repo

I've started the gogs-repo container as follows:

docker run --rm --name gogs-repo repo:0.1.0
usermod: no changes
Apr 26 10:37:56 syslogd started: BusyBox v1.31.1
2020/04/26 10:37:56 [TRACE] Log mode: File (Info)
Apr 26 10:37:57 sshd[36]: Server listening on :: port 22.
Apr 26 10:37:57 sshd[36]: Server listening on 0.0.0.0 port 22.

and as you can see, it is up and running. Why curl can the reach http://gogs-repo:3000?

回答1:

Assuming that your service is running on port 3000 inside container gogs-repo(because I am not sure after looking at the container logs), you should make the following changes in the existing setup.

First thing first. The two containers - gogs-repo and another container (from where you are trying to access the service) are not connected to each other. Hence the host gogs-repo is not resolved.

To fix this, you need to run both the containers in single network.

You can perform the following steps to achieve the desired result.

Create a private bridge network.

docker network create --driver bridge mynetwork

Now start your application containers along with the --network mynetwork added to your docker run command.

Finally, the updated docker run command looks like the following:

docker run --network mynetwork --rm --name gogs-repo repo:0.1.0

docker run --rm curlimages/curl:7.69.1 -L -v http://gogs-repo:3000

With the following changes, you are good to access http://gogs-repo:3000

Good read

Here is one more approach (easy but not recommended) to achieve the desired result.

Using Docker links

As mentioned here:

Links allow containers to discover each other and securely transfer information about one container to another container. When you set up a link, you create a conduit between a source container and a recipient container.

We can link the container from which we want to access the service using --link argument.

docker run --link gogs-repo:gogs-repo --rm curlimages/curl:7.69.1 -L -v http://gogs-repo:3000

What --link does is that it creates a secure tunnel between the containers that don’t need to expose any ports externally on the container.

来源：https://stackoverflow.com/questions/61439710/could-not-resolve-host-gogs-repo

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Docker