Last week Docker Community Edition 19.03.0 Beta 1 was announced and release notes went public here.Under this release, there were numerous exciting features which were introduced for the first time. Some of the notable features include – fast context switching, rootless docker, sysctl support for Swarm services, device support for Microsoft Windows.
Not only this, there were numerous enhancement around Docker Swarm, Docker Engine API, networking, Docker client, security & Buildkit. Below are the list of features and direct links to GitHub.
- Fast context switch: commands. docker/cli#1501
- Allow running dockerd as a non-root user (Rootless mode). moby/moby#380050
- Add sysctl support for services. docker/cli#1754
- Add –device support for Windows. docker/cli#1606
- Add support for maximum replicas per node without stack. docker/cli#1612
- Added support for maximum replicas per node. moby/moby#37940
- Add support for sysctl options in services. moby/moby#37701
- add SSH agent socket forwarder (
docker build --ssh $SSHMOUNTID=$SSH_AUTH_SOCK) docker/cli#1419 - Windows: Experimental: ContainerD runtime. moby/moby#38541
- LCOW: Add support for memory and CPU limits. moby/moby#37296
- Enable checkpoint/restore of containers with TTY. moby/moby#38405
- Add support for filtering on node labels. moby/moby#37650
Let’s talk about Context Switching..
A context is essentially the configuration that you use to access a particular cluster. Say, for example, in my particular case, I have 4 different clusters – mix of Swarm and Kubernetes running locally and remotely. Assume that I have a default cluster running on my Desktop machine , 2 node Swarm Cluster running on Google Cloud Platform, 5-Node Cluster running on Play with Docker playground and a single-node Kubernetes cluster running on Minikube and that I need to access pretty regularly. Using docker context CLI I can easily switch from one cluster(which could be my development cluster) to test to production cluster in seconds.
Under this blog post, I will focus on fast context switching feature which was introduced for the first time. Let’s get started:
Tested Infrastructure:
- A Node with Docker 19.03.0 Beta1 installed on Ubuntu 18.10
- 2 Docker Swarm Node Cluster(swarm-node1 and swarm-node2) setup on installed on Ubuntu 18.10
- 5-Node Swarm Cluster running on Play with Docker Platform
- Create 3 Node Kubernetes Cluster using GKE
Installing a Node with Docker 19.03.0 Beta 1 Test Build on Ubuntu 18.10
Method:I
Downloading the static binary archive. Go to https://download.docker.com/linux/static/stable/ (or change stable to nightly or test), choose your hardware platform, and download the .tgz file relating to the version of Docker CE you want to install.
Captain'sBay==>wget https://download.docker.com/linux/static/test/x86_64/docker-19.03.0-beta1.tgz
--2019-04-10 09:20:01-- https://download.docker.com/linux/static/test/x86_64/docker-19.03.0-beta1.tgz
Resolving download.docker.com (download.docker.com)... 54.230.75.15, 54.230.75.117, 54.230.75.202, ...
Connecting to download.docker.com (download.docker.com)|54.230.75.15|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 62701372 (60M) [application/x-tar]
Saving to: ‘docker-19.03.0-beta1.tgz’
docker-19.03.0-beta1.tgz 100%[=====================================>] 59.80M 10.7MB/s in 7.1s
2019-04-10 09:20:09 (8.38 MB/s) - ‘docker-19.03.0-beta1.tgz’ saved [62701372/62701372]
Extract the archive
You can use the tar utility. The dockerd and docker binaries are extracted.
Extract the tar file
Captain'sBay==>tar xzvf docker-19.03.0-beta1.tgz
docker/
docker/ctr
docker/containerd-shim
docker/dockerd
docker/docker-proxy
docker/runc
docker/containerd
docker/docker-init
docker/docker
Captain'sBay==>
Move the binaries to executable path
Move the binaries to a directory on your executable path It could be such as /usr/bin/. If you skip this step, you must provide the path to the executable when you invoke docker or dockerd commands.
Captain'sBay==>sudo cp -rf docker/* /usr/local/bin/
Start the Docker daemon:
$ sudo dockerd &
Client: Docker Engine - Community
Version: 19.03.0-beta1
API version: 1.40
Go version: go1.12.1
Git commit: 62240a9
Built: Thu Apr 4 19:15:07 2019
OS/Arch: linux/amd64
Experimental: false
Server: Docker Engine - Community
Engine:
Version: 19.03.0-beta1
API version: 1.40 (minimum version 1.12)
Go version: go1.12.1
Git commit: 62240a9
Built: Thu Apr 4 19:22:34 2019
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: v1.2.5
GitCommit: bb71b10fd8f58240ca47fbb579b9d1028eea7c84
runc:
Version: 1.0.0-rc6+dev
GitCommit: 2b18fe1d885ee5083ef9f0838fee39b62d653e30
docker-init:
Version: 0.18.0
GitCommit: fec3683
Captain'sBay==>
Testing with hello-world
Captain'sBay==>sudo docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
1b930d010525: Pull complete
Digest: sha256:2557e3c07ed1e38f26e389462d03ed943586f744621577a99efb77324b0fe535
Status: Downloaded newer image for hello-world:latest
INFO[2019-04-10T09:26:23.338596029Z] shim containerd-shim started address="/containerd-shim/m
oby/5b23a7045ca683d888c9d1026451af743b7bf4005c6b8dd92b9e95e125e68134/shim.sock" debug=false pid=2953
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
## Verifying the new `docker context` command
Method:II
If you have less time and want a single liner command to handle this, check this out –
root@DebianBuster:~# curl https://get.docker.com | CHANNEL=test sh
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 13063 100 13063 0 0 2305 0 0:00:05 0:00:05 --:--:-- 2971
# Executing docker install script, commit: 2f4ae48
+ sh -c apt-get update -qq >/dev/null
+ sh -c apt-get install -y -qq apt-transport-https ca-certificates curl >/dev/null
+ sh -c curl -fsSL "https://download.docker.com/linux/debian/gpg" | apt-key add -qq - >/dev/null
Warning: apt-key output should not be parsed (stdout is not a terminal)
+ sh -c echo "deb [arch=amd64] https://download.docker.com/linux/debian buster test" > /etc/apt/sources.list.d/docker.list
+ sh -c apt-get update -qq >/dev/null
+ [ -n ]
+ sh -c apt-get install -y -qq --no-install-recommends docker-ce >/dev/null
+ sh -c docker version
Client:
Version: 19.03.0-beta1
API version: 1.40
Go version: go1.11.5
Git commit: 62240a9
Built: Thu Apr 4 19:18:53 2019
OS/Arch: linux/amd64
Experimental: false
Server:
Engine:
Version: 19.03.0-beta1
API version: 1.40 (minimum version 1.12)
Go version: go1.11.5
Git commit: 62240a9
Built: Thu Apr 4 19:17:35 2019
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.2.5
GitCommit: bb71b10fd8f58240ca47fbb579b9d1028eea7c84
runc:
Version: 1.0.0-rc6+dev
GitCommit: 2b18fe1d885ee5083ef9f0838fee39b62d653e30
docker-init:
Version: 0.18.0
GitCommit: fec3683
If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:
sudo usermod -aG docker your-user
Remember that you will have to log out and back in for this to take effect!
WARNING: Adding a user to the "docker" group will grant the ability to run
containers which can be used to obtain root privileges on the
docker host.
Refer to https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface
for more information.
root@DebianBuster:~#
Verifying Docker version
root@DebianBuster:~# docker version
Client:
Version: 19.03.0-beta1
API version: 1.40
Go version: go1.11.5
Git commit: 62240a9
Built: Thu Apr 4 19:18:53 2019
OS/Arch: linux/amd64
Experimental: false
Server:
Engine:
Version: 19.03.0-beta1
API version: 1.40 (minimum version 1.12)
Go version: go1.11.5
Git commit: 62240a9
Built: Thu Apr 4 19:17:35 2019
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.2.5
GitCommit: bb71b10fd8f58240ca47fbb579b9d1028eea7c84
runc:
Version: 1.0.0-rc6+dev
GitCommit: 2b18fe1d885ee5083ef9f0838fee39b62d653e30
docker-init:
Version: 0.18.0
GitCommit: fec3683
root@DebianBuster:~#
Verifying docker context CLI
$ sudo docker context --help
Usage: docker context COMMAND
Manage contexts
Commands:
create Create a context
export Export a context to a tar or kubeconfig file
import Import a context from a tar file
inspect Display detailed information on one or more contexts
ls List contexts
rm Remove one or more contexts
update Update a context
use Set the current docker context
Run 'docker context COMMAND --help' for more information on a command.
Creating a 2 Node Swarm Cluster
Install Docker 19.03.0 Beta 1 on both the nodes(using the same method discussed above). You can use GCP Free Tier account to create 2-Node Swarm Cluster.
Configuring remote access with systemd unit file
Use the command sudo systemctl edit docker.service to open an override file for docker.service in a text editor.
Add or modify the following lines, substituting your own values.
Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H unix:///var/run/docker.sock -H tcp://10.140.0.6:2375
Save the file.
Reload the systemctl configuration
$ sudo systemctl daemon-reload Restart Docker.
$ sudo systemctl restart docker.serviceRepeat it for other nodes which you are planning to include for building Swarm Mode cluster.
swarm-node-1:~$ sudo docker swarm init --advertise-addr 10.140.0.6 --listen-addr 10.140.0
.6:2377
Swarm initialized: current node (c78wm1g99q1a1g2sxiuawqyps) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-1bc88158q1v4b4gdof8k0u532bxzdvrgxfztwgj2r443337mja-cmhuu258lu0327
e32l0g4pl47 10.140.0.6:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
Run the below command on worker node:
swarm-node2:~$ sudo docker swarm join --token SWMTKN-1-1bc88158q1v4b4gdof8k0u532bxzdvrgxf
ztwgj2r443337mja-cmhuu258lu0327e32l0g4pl47 10.140.0.6:2377
This node joined a swarm as a worker.
Listing the Swarm Mode CLuster
root@swarm-node-1:~# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
0v5r9xmpbxzqpy72u41ihfck0 swarm-node2 Ready Active 19.03.0-beta1
xwmay5i48xxbzlp7is7a3uord * swarm-node-1 Ready Active Leader 19.03.0-beta1
Switching the Context
Listing the Context
node-1:~$ sudo docker context ls
NAME DESCRIPTION DOCKER ENDPOINT KUBERNETES E
NDPOINT ORCHESTRATOR
default * Current DOCKER_HOST based configuration unix:///var/run/docker.sock
swarm
Adding the new Context
docker context create --docker host=tcp://10.140.0.6:2375 swarm-context1
Using the new context for Swarm
docker context use swarm-context1
Listing the Swarm Mode Cluster
sudo docker context ls
NAME DESCRIPTION DOCKER ENDPOINT KUBERNETES E
NDPOINT ORCHESTRATOR
default Current DOCKER_HOST based configuration unix:///var/run/docker.sock
swarm
swarm-context1 * tcp://10.140.0.6:2375
sudo docker context ls --format '{{json .}}' | jq .
{
"Current": true,
"Description": "Current DOCKER_HOST based configuration",
"DockerEndpoint": "unix:///var/run/docker.sock",
"KubernetesEndpoint": "",
"Name": "default",
"StackOrchestrator": "swarm"
}
{
"Current": false,
"Description": "",
"DockerEndpoint": "tcp://10.140.0.6:2375",
"KubernetesEndpoint": "",
"Name": "swarm-context1",
"StackOrchestrator": ""
}
$ sudo docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS
ENGINE VERSION
xwmay5i48xxbzlp7is7a3uord * swarm-node-1 Ready Active Leader
19.03.0-beta1
$ sudo docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
0v5r9xmpbxzqpy72u41ihfck0 swarm-node2 Ready Active 19.03.0-beta1
xwmay5i48xxbzlp7is7a3uord * swarm-node-1 Ready Active Leader 19.03.0-beta1
tanvirkour1985@sys1:~$ Context Switching to remotely running Play with Docker(PWD) Platform
This is one of the most exciting part of this blog. I simply love PWD platform as I find it perfect playground for test driving Docker Swarm cluster. Just a click and you get 5-Node Docker Swarm Cluster in just 5 seconds.
Just click on 3-Manager and 2 workers and you get 5-Node Docker Swarm cluster for FREE.
Let us try to access this PWD cluster using docker context CLI.
Say, by default we have just 1 context for local Docker Host.
[:)Captain'sBay=>sudo docker context ls
NAME DESCRIPTION DOCKER ENDPOINT KUBERNETES ENDPOINT ORCHESTRATOR
default * Current DOCKER_HOST based configuration unix:///var/run/docker.sock https://127.0.0.1:16443 (default) swarm
swarm-context1 tcp://10.140.0.6:2375
Let us go ahead and add PWD context. As shown below, you need to pick up the FQDN name but remember to remove “@” and replace it with “.”(dot)
[:)Captain'sBay=>sudo docker context create --docker host=tcp://ip172-18-0-5-biosq9o6chi000as1470.direct.labs.play-with-docker.com:2375 pwd-clu
ster1
pwd-cluster1
Successfully created context "pwd-cluster1"
This creates a context by name “pwd-cluster1”. You can verify it by listing out the current contexts available.
[:)Captain'sBay=>sudo docker context ls
NAME DESCRIPTION DOCKER ENDPOINT K
UBERNETES ENDPOINT ORCHESTRATOR
default * Current DOCKER_HOST based configuration unix:///var/run/docker.sock h
ttps://127.0.0.1:16443 (default) swarm
pwd-cluster1 tcp://ip172-18-0-5-biosq9o6chi000as1470.direct.labs.play-with-docker.com:2375
swarm-context1 tcp://10.140.0.6:2375
[:)Captain'sBay=>
Let us switch to pwd-cluster1 by simply typing docker context use CLI.
[:)Captain'sBay=>sudo docker context use pwd-cluster1
pwd-cluster1
Current context is now "pwd-cluster1"
Listing out the context and verifying if it points to right PWD cluster.
[:)Captain'sBay=>sudo docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
wnrz5fks5drzs9agkyl8z3ffi * manager1 Ready Active Leader 18.09.4
dcweon0icoolfs3kirj0p3qgg manager2 Ready Active Reachable 18.09.4
f78bkvfbzot2jkr2n6cen7240 manager3 Ready Active Reachable 18.09.4
xla6nb5ql5i6pkjruyxpc1hzk worker1 Ready Active 18.09.4
45nk1t94ympplgaasiryunwvk worker2 Ready Active 18.09.4
[:)Captain'sBay=>
In my next blog post, I will showcase how to switch to Kubernetes cluster running on Minikube and GKE using compose on Kubernetes.
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