Starting Docker Daemon on CentOS

Q

How to start Docker Daemon, "dockerd", on CentOS systems?

✍: FYIcenter.com

A

If you have installed Docker on your CentOS system, you follow these steps to start the Docker Daemon, "dockerd".

1. Verify Docker installation path.

fyicenter$ which dockerd
  /usr/bin/dockerd

2. Start Docker Daemon using the "dockerd" command. But it needs "root" permission. It still fails to start Container Daemon.

fyicenter$ dockerd
  INFO[09:51:59.778175452+08:00] Starting up
  dockerd needs to be started with root.
  To see how to run dockerd in rootless mode with unprivileged user,
  see the documentation

fyicenter$ sudo dockerd &
INFO[...] Starting up
WARN[...] could not change group /var/run/docker.sock to docker: group docker not found
INFO[...] parsed scheme: "unix"                         module=grpc
INFO[...] scheme "unix" not registered, fallback to default scheme  module=grpc
INFO[...] ClientConn switching balancer to "pick_first"  module=grpc
WARN[...] grpc: addrConn.createTransport failed to connect
  to {unix:///run/containerd/containerd.sock <nil> 0 <nil>}.
  Err :connection error: desc = "transport: Error while dialing
  dial unix /run/containerd/containerd.sock: connect: connection refused".
  Reconnecting...  module=grpc

3. Log in as "root" and start Docker Daemon again.

fyicenter# dockerd &

INFO[...] Starting up
WARN[...] could not change group /var/run/docker.sock to docker: group docker not found
INFO[...] libcontainerd: started new containerd process  pid=3145420
INFO[...] parsed scheme: "unix"                         module=grpc
INFO[...] scheme "unix" not registered, fallback to default scheme  module=grpc
INFO[...] ClientConn switching balancer to "pick_first"  module=grpc
INFO[...] starting containerd version=v1.4.6
INFO[...] loading plugin "io.containerd.content.v1.content"...  type=io.containerd.content.v1
INFO[...] loading plugin "io.containerd.snapshotter.v1.aufs"...  type=io.containerd.snapshotter.v1
INFO[...] serving... address=/var/run/docker/containerd/containerd-debug.sock
INFO[...] serving... address=/var/run/docker/containerd/containerd.sock.ttrpc
INFO[...] serving... address=/var/run/docker/containerd/containerd.sock
INFO[...] containerd successfully booted in 0.023700s
INFO[...] using prior storage driver: overlay2
WARN[...] Your kernel does not support cgroup blkio weight
WARN[...] Your kernel does not support cgroup blkio weight_device
INFO[...] Loading containers: start.
INFO[...] Firewalld: docker zone already exists, returning
INFO[...] Firewalld: interface docker0 already part of docker zone, returning
INFO[...] Firewalld: interface docker0 already part of docker zone, returning
INFO[...] Default bridge (docker0) is assigned with an IP address 172.17.0.0/16. Daemon option --bip can be used to set a preferred IP address
INFO[...] Firewalld: interface docker0 already part of docker zone, returning
INFO[...] Loading containers: done.
INFO[...] Docker daemon commit=b0f5bc3 graphdriver(s)=overlay2 version=20.10.7
INFO[...] Daemon has completed initialization
INFO[...] API listen on /var/run/docker.sock

4. Verify Docker Daemon.

fyicenter$ sudo ps -efl | grep docker
  - 264001 -     12:24 pts/14   00:00:00 dockerd
  - 275268 -     12:24 ?        00:00:00 containerd --config \
    /var/run/docker/containerd/containerd.toml --log-level info

fyicenter$ sudo docker info
  Client:
   Context:    default
   Debug Mode: false

  Server:
   Containers: 0
    Running: 0
    Paused: 0
    Stopped: 0
   Images: 0
   Server Version: 20.10.7
   Storage Driver: overlay2
    Backing Filesystem: xfs
  ...

5. Possible issue when starting the Docker binary package is the $PATH access to the "containerd" command. You need to add the "./docker" directory to $PATH.

fyicenter$ su

fyicenter# ./docker/dockerd
  INFO[09:53:51.388587173+08:00] Starting up
  failed to start containerd: exec: "containerd":
    executable file not found in $PATH

fyicenter# export PATH=/home/fyicenter/docker:$PATH

fyicenter# ./docker/dockerd
  ...
  INFO[...] starting containerd version=v1.4.6
  INFO[...] containerd successfully booted in 0.023700s
  INFO[...] Docker daemon commit=b0f5bc3 graphdriver(s)=overlay2 version=20.10.7
  INFO[...] Daemon has completed initialization
  INFO[...] API listen on /var/run/docker.sock

 

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2023-03-17, 3533🔥, 0💬