How docker checks network status

In Docker, the network is a very important part. Because each container needs to be connected to the Internet to complete various functions and interactions. However, network status problems are common, such as being unable to connect to the external network, excessive network latency, etc. Therefore, it is very necessary for Docker users to understand how to query and solve network problems.

In this article, we will discuss how to query the Docker network status and how to solve common network problems.

1. Query the Docker network status

We can use Docker’s own tools or third-party tools to query the network status. Let’s introduce them separately below.

1. Docker comes with tools

Docker provides some built-in commands to query network status. These commands can quickly query Docker network configuration, network topology, network connections and Network traffic and other information.

1) Query Docker network configuration

We can use the following command to query Docker network configuration information:

docker network ls

This command will list all available Docker networks, including their Name, ID, driver type, subnet, gateway, etc.

2) Query the Docker network topology

We can use the following command to view the Docker network topology:

docker network inspect

This command will return a network topology in JSON format, which contains All connections between containers and the network.

3) Query the Docker network connection

We can use the docker network connect command to connect the container and the network. Use the following command to query the connection between the container and the network:

docker network inspect <network_name>

This command will return a network topology in JSON format, which has a "Containers" field, which lists All containers connected to this network.

4) Query Docker network traffic

We can use the docker stats command to query the resource usage of the Docker container, which contains network traffic information:

docker stats <container_name>

This command will output the real-time resource usage of the specified container, including CPU, memory, network traffic, disk, etc.

2. Third-party tools

In addition to the tools that come with Docker, third-party tools are also a good choice. The following are some commonly used third-party tools:

1) netstat

netstat is a common network diagnostic tool that can be used to view network connection status, process information, etc. wait. We can use this command to query the network connection status of the Docker container.

netstat -antp | grep <container_id>

This command will return all network connection information and corresponding process information of the specified container.

2) tcptraceroute

tcptraceroute can diagnose the TCP connection path and network delay and other information. If we want to test the network conditions between the Docker container and the target server, we can use this tool to diagnose.

tcptraceroute <destination_ip>

This command will output information such as the path from the Docker container to the target server and network delay.

3) iperf

iperf is a network bandwidth testing tool that can be used to test network bandwidth, delay and other information. If we want to test the network bandwidth between the Docker container and the target server, we can use this tool to test.

iperf -c <destination_ip>

This command will output the network bandwidth information from the Docker container to the target server.

2. Solve common network problems

During the Docker network configuration process, we may encounter some common network problems. Let's solve these problems below.

1. The container cannot connect to the external network

This is the most common network problem. We need to check the following points:

1) Check the host Is the DNS configuration correct?

2) Check whether the Docker network configuration is correct. Incorrect Docker network configuration may cause the container to be unable to connect to the external network.

3) Check whether the container’s network connection is normal.

2. The network delay is too high

The network delay is too high. It may be that the network delay between the container and the target server is too large. We can solve it by the following methods:

1) Increase bandwidth and improve network transmission speed.

2) Adjust the distance between the container and the target server to shorten the network delay as much as possible.

3) Optimize the program code in the container to reduce network latency.

3. Containers cannot access each other

It is also a common problem that containers cannot access each other. We need to check the following points:

1) Check whether the Docker network configuration is correct.

2) Check whether the port of the container is correct.

3) Check whether the IPv4 address of the container is correct.

4) Check whether the container ID of the container is correct.

Summary

Network status problems are very common, and in Docker we need to carefully check the network configuration and solve network problems. Through the introduction of this article, we can know how to query the Docker network status and solve common network problems. I believe these tips will definitely help you solve network problems when using Docker.

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