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What is a bridge network?

DockerMiddle~1 min read
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bridge is a virtual network that Docker creates on the host to connect containers with each other. It works like an internal router: each container gets its own private IP, and Docker automatically sets up routes and a built-in DNS.

How bridge works:

  • when a container starts, Docker connects it to the bridge network and assigns it an IP (for example, 172.17.0.2);
  • containers in this network can reach each other by IP or by container/service name;
  • access to the outside world goes through NAT on the host;
  • from the outside, the container is unreachable until ports are published.

When bridge is used:

  • for local development;
  • for small projects on a single host;
  • for scenarios where services need to see each other but stay hidden from the outside network.

Example:

bash
docker run -d --name app nginx docker run -d --name db mysql

Both containers end up in the bridge network and can communicate, for example: mysql://db:3306.

Key features of bridge:

PropertyDescription
Isolated from the hostContainers are in their own private network
Has DNSContainers see each other by name
NAT outwardContainers have internet access
Ports required for inbound access-p 8080:80

Summary: bridge is a local private Docker network for containers on a single host to interact, isolated from the outside network with a convenient internal DNS.

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