access docker daemon remote api in contanier - docker

Question

I use official version of docker-ce at centos7, start a docker daemon in container:
[root#5cae7be526b4 /]# rpm -qa docker-ce
docker-ce-17.09.0.ce-1.el7.centos.x86_64
Here is my daemon config
{
"hosts": ["unix:///var/run/docker.sock", "tcp://0.0.0.0:5555"],
"live-restore": true,
"insecure-registries": ["172.17.0.6:9980"]
}
Without changing config, docker daemon can start and restart in container:
[root#5cae7be526b4 /]# docker info
Containers: 0
Running: 0
Paused: 0
Stopped: 0
Images: 0
Server Version: 17.09.0-ce
Storage Driver: vfs
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge host macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 06b9cb35161009dcb7123345749fef02f7cea8e0
runc version: 3f2f8b84a77f73d38244dd690525642a72156c64
init version: 949e6fa
Security Options:
seccomp
Profile: default
Kernel Version: 3.10.0-514.el7.x86_64
Operating System: CentOS Linux 7 (Core) (containerized)
OSType: linux
Architecture: x86_64
CPUs: 16
Total Memory: 31.26GiB
Name: 5cae7be526b4
ID: N3Y4:VTIJ:WCHK:AQL3:MU3F:DNHE:BIXO:7ISI:4D4V:Q4IG:VYIT:FOH3
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled
But change the config, it failed:
[root#5cae7be526b4 /]# systemctl restart docker
Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
[root#5cae7be526b4 /]# systemctl status docker -l
● docker.service - Docker Application Container Engine
Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
Active: failed (Result: start-limit) since Thu 2017-11-02 05:51:02 UTC; 2s ago
Docs: https://docs.docker.com
Process: 260 ExecStart=/usr/bin/dockerd (code=exited, status=1/FAILURE)
Main PID: 260 (code=exited, status=1/FAILURE)
Nov 02 05:51:02 5cae7be526b4 systemd[1]: Failed to start Docker Application Container Engine.
Nov 02 05:51:02 5cae7be526b4 systemd[1]: Unit docker.service entered failed state.
Nov 02 05:51:02 5cae7be526b4 systemd[1]: docker.service failed.
Nov 02 05:51:02 5cae7be526b4 systemd[1]: docker.service holdoff time over, scheduling restart.
Nov 02 05:51:02 5cae7be526b4 systemd[1]: start request repeated too quickly for docker.service
Nov 02 05:51:02 5cae7be526b4 systemd[1]: Failed to start Docker Application Container Engine.
Nov 02 05:51:02 5cae7be526b4 systemd[1]: Unit docker.service entered failed state.
Nov 02 05:51:02 5cae7be526b4 systemd[1]: docker.service failed.
Of course, this daemon config can run at host.
I has start container with --privileged and -v /sys/fs/cgroup:/sys/fs/cgroup to enable use systemctl in container.
The root cause is "hosts": ["unix:///var/run/docker.sock", "tcp://0.0.0.0:5555"], i do not know how to fix it but i need to set host indeed.
I want to make this container as a repo and start other container to do docker action like pull from this docker daemon.
How can i enable it?

Answer 1

I share my solution here, please tell me if wrong or has a better way.
First, check docker version, only new official version can run in container. For centos, it means docker-ce, refer to https://docs.docker.com/engine/installation/linux/docker-ce/centos/
Second, check the host port doesn't be set as -p when start container. docker daemon can listen it and specify with -p would make conflicts.
Third, start docker daemon in container should assign a volume for storage. If not, the storage option only can be vfs.