ローカルの Ubuntu システムで次のコマンドを実行して Docker イメージをビルドしているときに、DNS 解決の問題が発生しました。Dockerfile で GoProxy を使用してアリババクラウドのプロキシを指定しましたが、ビルド時に DNS を解決できませんでした。
sudo docker compose -f ./compose-dev.yaml build
[+] Building 2.0s (9/14)
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 1.27kB 0.0s
=> [internal] load metadata for docker.io/library/golang:1.20-buster 1.5s
=> [builder 1/7] FROM docker.io/library/golang:1.20-buster@sha256:73c225bc5e2353f20dbe0466819b70a51a114a93bfe4af035a3bb9e1ecdd4107 0.0s
=> [internal] load build context 0.0s
=> => transferring context: 812.84kB 0.0s
=> CACHED [builder 2/7] RUN mkdir -p /app 0.0s
=> CACHED [builder 3/7] WORKDIR /app 0.0s
=> [builder 4/7] COPY . /app 0.0s
=> ERROR [builder 5/7] RUN go env -w GOPROXY=https://mirrors.aliyun.com/goproxy/,direct && go get -d -v ./... 0.3s
------
> [builder 5/7] RUN go env -w GOPROXY=https://mirrors.aliyun.com/goproxy/,direct && go get -d -v ./...:
#0 0.313 go: github.com/BurntSushi/toml@v0.3.1: Get "https://mirrors.aliyun.com/goproxy/github.com/%21burnt%21sushi/toml/@v/v0.3.1.mod": dial tcp: lookup mirrors.aliyun.com on [240e:d:0:100::6]:53: dial udp [240e:d:0:100::6]:53: connect: cannot assign requested address
------
failed to solve: process "/bin/sh -c go env -w GOPROXY=https://mirrors.aliyun.com/goproxy/,direct && go get -d -v ./..." did not complete successfully: exit code: 1
解決方法は /etc/docker/daemon.json に DNS を設定することです。例えば：
{
"dns": ["8.8.8.8", "8.8.4.4"],
"log-driver": "json-file",
"log-opts": {
"max-size": "50m",
"max-file": "3"
}
}