Docker daemon已运行但无法连接，拉取镜像失败求助

It looks like your Docker client is trying to connect to a Docker daemon running on a virtual machine at tcp://192.168.99.102:2376—this is typical if you’re using Docker Toolbox (which relies on a VirtualBox VM) instead of Docker Desktop’s native local daemon. Let’s walk through targeted fixes since you’ve already tried basic steps like restarting the service and using sudo:

Step 1: Check Docker Machine VM Status #

First, confirm the underlying VM is running and accessible:

• List your Docker Machine instances to verify the VM state:

  docker-machine ls
  

• Look for the VM linked to 192.168.99.102 (usually named default). If its status shows Stopped, start it with:

  docker-machine start default
  

• Load the required environment variables to point your Docker client to this VM:

  eval $(docker-machine env default)
  

  This sets DOCKER_HOST, DOCKER_TLS_VERIFY, and DOCKER_CERT_PATH to the correct values for the VM.

Step 2: Clear Stale Environment Variables (If Using Docker Desktop) #

If you switched from Docker Toolbox to Docker Desktop, leftover environment variables might force the client to connect to the wrong daemon:

• Clear the conflicting variables:

  unset DOCKER_HOST DOCKER_TLS_VERIFY DOCKER_CERT_PATH
  

• Close and reopen your terminal to apply the change, then try the docker pull command again.

Step 3: Validate TLS Certificates #

Port 2376 uses TLS encryption, so missing or corrupted certificates can block connections:

• Check if your certificate path is correctly configured:

  echo $DOCKER_CERT_PATH
  

  It should point to a path like ~/.docker/machine/machines/default.
• If certificates are missing or corrupted, regenerate them:

  docker-machine regenerate-certs default
  

• Reload the environment variables again with eval $(docker-machine env default) and test the pull command.

Step 4: Test Direct Connection with Manual TLS Params #

If the above steps fail, manually specify the daemon address and certificates to rule out environment issues:

docker -H tcp://192.168.99.102:2376 \
  --tlsverify \
  --tlscacert=~/.docker/machine/machines/default/ca.pem \
  --tlscert=~/.docker/machine/machines/default/cert.pem \
  --tlskey=~/.docker/machine/machines/default/key.pem \
  pull osixia/phpldapadmin:latest

Step 5: Check Network/Firewall Blockages #

• Verify you can ping the VM IP to confirm network connectivity:

  ping 192.168.99.102
  

  If ping fails, restart the VM with docker-machine restart default or check VirtualBox’s network settings for the VM.
• Temporarily disable your local firewall (e.g., sudo ufw disable on Ubuntu) to rule out port blocking, then test the pull command again. Remember to re-enable the firewall afterward.

内容的提问来源于stack exchange，提问作者Juan David Porras Palencia