pull镜像wordpress下来，但是出现如下错误：
# docker pull wordpress:latest
Error response from daemon: Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaitin headers)
查看日志，发现出现如下错误：
#tailf /var/log/messages
Aug 19 16:46:29 docker02 dockerd: time="2019-08-19T16:46:29.157861585+08:00" level=warning msg="Error getting v2 registry: Get https://registry.docker-cn.com/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)"
Aug 19 16:46:29 docker02 dockerd: time="2019-08-19T16:46:29.157965774+08:00" level=info msg="Attempting next endpoint for pull after error: Get https://registry.docker-cn.com/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)"
Aug 19 16:46:44 docker02 dockerd: time="2019-08-19T16:46:44.158651847+08:00" level=warning msg="Error getting v2 registry: Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)"
Aug 19 16:46:44 docker02 dockerd: time="2019-08-19T16:46:44.158907684+08:00" level=info msg="Attempting next endpoint for pull after error: Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)"
Aug 19 16:46:44 docker02 dockerd: time="2019-08-19T16:46:44.159189201+08:00" level=error msg="Handler for POST /v1.40/images/create returned error: Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)"
发现是因为docker加速器超时导致pull不下来
查看加速器：/etc/docker/daemon.json
# cat /etc/docker/daemon.json
{
"registry-mirrors": ["https://registry.docker-cn.com"],
"insecure-registries": ["10.0.0.12:5000"]
}
导致此问题产生，主要是因为国家把docker国外镜像hub封掉了，导致镜像pull不下来，为此，改用国内的镜像
# cat /etc/docker/daemon.json
{
"registry-mirrors": ["https://docker.mirrors.ustc.edu.cn/","https://hub-mirror.c.163.com","https://registry.docker-cn.com"],
"insecure-registries": ["10.0.0.12:5000"]
}
#systemctl restart docker
# docker pull wordpress:latest
latest: Pulling from library/wordpress
1ab2bdfe9778: Pulling fs layer
1448c64389e0: Pulling fs layer
4b8a4e62b444: Pulling fs layer
9eb9d1e8e241: Pulling fs layer
d20b2d19292c: Pull complete
023060ea5930: Pull complete
a7fa99bc84ac: Pull complete
138ec8da18f2: Pull complete
cd4dae5ac262: Pull complete
c90eff48869a: Pull complete
1bc49f4d3a43: Pull complete
e3bb2b10f58d: Pull complete
fd7b454ec570: Pull complete
6096f23889f4: Pull complete
81072ed817d5: Pull complete
ecce7df16ad3: Pull complete
f4475635015e: Pull complete
bad34b7324ad: Pull complete
890f49d5ad8a: Pull complete
7e4ee285d305: Pull complete
Digest: sha256:6566a68d0c613304aa11255d98aba6e29c5fa8cd8497064639343956a4c7d2b1
Status: Downloaded newer image for wordpress:latest
docker.io/library/wordpress:latest
可以正常Pull下来了。