What is Docker Swarm?
- Compare the Docker
The Docker can understand as we introduce before is one of our service independent operation of the container, so in practice, our systems may be a micro service application, system according to the business is divided into several modules, can understand a module corresponding to a set of running the same mirror Docker container, this is a single Docker, Swarm is the orchestration tool that manages routing, load balancing, service discovery, container scaling, logs and configuration files among all containers in the system.
- Compare the Docker – Compose
Docker-compose is similar to our daily housekeeper in that it only manages all the containers on a host and can start multiple containers at once. Docker-swarm can manage multiple containers across hosts, and when a container state is abnormal, it can quickly start containers on other machines, to ensure high availability of service!
- Contrast Kubernetes
Kubernetes itself has the same role positioning as Docker Swarm, that is to say, they are responsible for the same part of the container field, they are a cross-host container management platform, of course, there are some different characteristics. K8s is a container management platform developed by Google based on its own years of experience in operation and maintenance. Docker Swarm was developed by Docker. Kubernetes encapsulates a layer of concepts on top of Docker, so Swarm is more powerful than Docker, but more complex to operate, and easier to use.
Docker is a container, docker-compose is a single-host scheduling tool, docker-swarm is a multi-host scheduling tool!
- Swarm architecture composition
- Docker Api is based on Docker to manage containers
- Swarm Manage CLi is the Swarm management Api
- Leadership is the HA provided by Swarm
- Scheduler is Swarm’s scheduling policy and filtering rule management
- The Discovery Service manages the registration and Discovery of services for each container
- How does Swarm work? Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker Docker But only one management node can be the Leader. The work node is the task execution node.
- Manager nodes:
- Handle cluster management tasks
- Maintaining Cluster Status
- The scheduler
- Swarm provides an external callable API interface
- Worker node: Docker container that actually performs our service
- Manager nodes:
Docker Swarm command
- Initializing a Cluster
$docker swarm init --advertise-addr 192.168.99.121
Swarm initialized: current node (bvz81updecsj6wjz393c09vti) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join \
--token SWMTKN-1-3pu6hszjas19xyp7ghgosyx9k8atbfcr8p2is99znpy26u2lkl-1awxwuwd3z9j1z3puu7rcgdbx \
172.17.0.2:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
Copy the code- To join the cluster
# to join the worker
$ docker swarm join-token worker
To add a worker to this swarm, run the following command:
docker swarm join \
--token SWMTKN-1-3pu6hszjas19xyp7ghgosyx9k8atbfcr8p2is99znpy26u2lkl-1awxwuwd3z9j1z3puu7rcgdbx \
172.17.0.2:2377
# to join manager
$ docker swarm join-token manager
To add a manager to this swarm, run the following command:
docker swarm join \
--token SWMTKN-1-3pu6hszjas19xyp7ghgosyx9k8atbfcr8p2is99znpy26u2lkl-7p73s1dx5in4tatdymyhg9hu2 \
172.17.0.2:2377
Copy the code- Leave the cluster
# --force / -f Force leave
$ docker swarm leave -f
Node left the default swarm.
Copy the code- Query cluster node information
docker@manager:~$ docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
Alz0od3rbkg552mkicfuezhkn * manager Ready Active Leader 19.03.12
Ready Active 19.03.12 jxf5u2hnurrgz90vnd9ay3y7p node - 1
Ready Active 19.03.12 lldvm2slseyodo0t7ath5tzne node - 2
Copy the code- Swarm Created a service in the cluster
Docker service create --name redis redis:3.0.6
dmu1ept4cxcfe8k8lhtux3ro3
$docker service create --mode global --name redis2 redis:3.0.6
a8q9dasaafudfs8q8w32udass
$ docker service ls
ID NAME MODE REPLICAS IMAGE
Dmu1ept4cxcf Redis Replicated 1/1 Redis :3.0.6
A8q9dasaafud redis2 Global 1/1 Redis :3.0.6
Copy the code- Example View swarm cluster service information
$ docker service inspect redis
Copy the code- View service logs
$ docker service logs -f redis
Copy the code- View start all services
$ docker service ls
ID NAME MODE REPLICAS IMAGE
c8wgl7q4ndfd frontend replicated 5/5 nginx:alpine
Dmu1ept4cxcf Redis Replicated 3/3 Redis :3.0.6
Iwe3278osahj Mongo Global 7/7 Mongo :3.3
hh08h9uu8uwr job replicated-job 1/1 (3/5 completed) nginx:latest
Copy the code- View the specific container in which the service is started
$ docker service ps redis
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
0qihejybwf1x redis.1 redis:3.0.5 manager1 Running Running 8 seconds
Bk658fpbex0d redis.2 redis:3.0.5 worker2 Running Running 9 seconds
5LS5S5FLDAqg redis.3 redis:3.0.5 worker1 Running 9 seconds
Copy the code- Remove the service
$ docker service rm redis
redis
$ docker service ls
ID NAME MODE REPLICAS IMAGE
Copy the code- Swarm-cluster service (you can dynamically add service providers to a swarm node cluster.)
docker service create --mode global ... : Start the service 🈯️ set --mode global cannot use this command. Global creates a service and starts one on each node
Expand the frontend service by 50 nodes
$ docker service scale frontend=50
frontend scaled to 50
Copy the code- Specify parameters to update specific references
https://docs.docker.com/engine/reference/commandline/service_update/
Swarm combat drill
Create three VMS using dcoker-machine
1. Create three hosts
docker-machine create --driver=virtualbox manager
docker-machine create --driver=virtualbox node-1
docker-machine create --driver=virtualbox node-2
[root@docker ~]# docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS
Manager - virtualbox Running TCP: / / 192.168.99.100:2376 v19.03.12
Node - 1 - virtualbox Running TCP: / / 192.168.99.103:2376 v19.03.12
Node - 2 - virtualbox Running TCP: / / 192.168.99.102:2376 v19.03.12
Copy the code2. After creating hosts, initialize the Swarm Manager node
[root@docker ~]# docker-machine ssh manager
( '>')
/) TC (\ Core is distributed with ABSOLUTELY NO WARRANTY.
(/-_--_-\) www.tinycorelinux.net
--advertise-addr Specifies the IP address of the manager
docker@manager:~$docker swarm init --advertise-addr 192.168.99.100
Swarm initialized: current node (alz0od3rbkg552mkicfuezhkn) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-4mocuep5w9jhd05bww7h0rzwhd1ayd1o3i2lncwkk2cw1rv9d2-9ed4ny56zt7ygw69dok39id8w 192.168.99.100:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
Copy the codeSo that’s how you initialize the manager isn’t that easy?
3. Switch to Node-1 and Node-2 and add them to the cluster
Swarm swarm # node-1 joined swarm
[root@docker ~]# docker-machine ssh node-1
( '>')
/) TC (\ Core is distributed with ABSOLUTELY NO WARRANTY.
(/-_--_-\) www.tinycorelinux.net
docker@node-1:~$ docker swarm join --token SWMTKN mocuep5w9jhd05bww7h0rzwhd1ayd1o3i2lncwkk2cw1rv9d2-9-1-4 ed4ny56zt7ygw69dok39id8w 192.168.99.100:2377
This node joined a swarm as a worker.
#node-2 joined the swarm
[root@docker ~]# docker-machine ssh node-2
( '>')
/) TC (\ Core is distributed with ABSOLUTELY NO WARRANTY.
(/-_--_-\) www.tinycorelinux.net
docker@node-2:~$ docker swarm join --token SWMTKN mocuep5w9jhd05bww7h0rzwhd1ayd1o3i2lncwkk2cw1rv9d2-9-1-4 ed4ny56zt7ygw69dok39id8w 192.168.99.100:2377
This node joined a swarm as a worker
Copy the code- Check the cluster node status in manager
docker@manager:~$ docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
Alz0od3rbkg552mkicfuezhkn * manager Ready Active Leader 19.03.12
Ready Active 19.03.12 jxf5u2hnurrgz90vnd9ay3y7p node - 1
Ready Active 19.03.12 lldvm2slseyodo0t7ath5tzne node - 2
Copy the code- Create an Nginx service that contains three copies
--replicas specifies the number of replicas
docker@manager:~$ docker service create --name test-nginx --publish 8080:80 --replicas=3 nginx
ya3q60llnj62w141aaekggyl2
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
docker@manager:~$ docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
ya3q60llnj62 test-nginx replicated 3/3 nginx:latest *:8080->80/tcp
Copy the codeNginx services can be accessed randomly from any nginx service as long as the manager IP address is 8080.
# send multiple requests to nginx service
The curl 192.168.99.100:8080
# check log
docker@manager:~$ docker service logs -f ya3q60llnj62
test-nginx.1.h50ridnlpsim@node-2 | /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
test-nginx.1.h50ridnlpsim@node-2 | /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
test-nginx.1.h50ridnlpsim@node-2 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
test-nginx.1.h50ridnlpsim@node-2 | 10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
test-nginx.1.h50ridnlpsim@node-2 | 10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
test-nginx.1.h50ridnlpsim@node-2 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
test-nginx.1.h50ridnlpsim@node-2 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
test-nginx.1.h50ridnlpsim@node-2 | /docker-entrypoint.sh: Configuration complete; ready for start up
test- nginx. H50ridnlpsim @ node - 2 | 10.0.0.2 - [25 / Mar 2021:14:59:30 + 0000]"The GET/HTTP / 1.1"200, 612,"-" "Curl / 7.29.0" "-"
test- nginx. H50ridnlpsim @ node - 2 | 10.0.0.2 - [25 / Mar 2021:14:59:33 + 0000]"The GET/HTTP / 1.1"200, 612,"-" "Curl / 7.29.0" "-"
test-nginx.3.mw75ab00bfs1@node-1 | /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
test-nginx.3.mw75ab00bfs1@node-1 | /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
test-nginx.3.mw75ab00bfs1@node-1 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
test-nginx.3.mw75ab00bfs1@node-1 | 10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
test-nginx.3.mw75ab00bfs1@node-1 | 10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
test-nginx.3.mw75ab00bfs1@node-1 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
test-nginx.3.mw75ab00bfs1@node-1 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
test-nginx.3.mw75ab00bfs1@node-1 | /docker-entrypoint.sh: Configuration complete; ready for start up
test- nginx. | 3. Mw75ab00bfs1 @ node - 1 10.0.0.2 - [25 / Mar 2021:14:59:28 + 0000]"The GET/HTTP / 1.1"200, 612,"-" "Curl / 7.29.0" "-"
test- nginx. | 3. Mw75ab00bfs1 @ node - 1 10.0.0.2 - [25 / Mar 2021:14:59:31 + 0000]"The GET/HTTP / 1.1"200, 612,"-" "Curl / 7.29.0" "-"
test- nginx. | 3. Mw75ab00bfs1 @ node - 1 10.0.0.2 - [25 / Mar 2021:14:59:34 + 0000]"The GET/HTTP / 1.1"200, 612,"-" "Curl / 7.29.0" "-"
test-nginx.2.drsv2s4cnf9y@manager | /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
test-nginx.2.drsv2s4cnf9y@manager | /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
test-nginx.2.drsv2s4cnf9y@manager | /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
test-nginx.2.drsv2s4cnf9y@manager | 10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
test-nginx.2.drsv2s4cnf9y@manager | 10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
test-nginx.2.drsv2s4cnf9y@manager | /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
test-nginx.2.drsv2s4cnf9y@manager | /docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
test-nginx.2.drsv2s4cnf9y@manager | /docker-entrypoint.sh: Configuration complete; ready for start up
test- nginx. 2. Drsv2s4cnf9y @ manager | 10.0.0.2 - [25 / Mar 2021:14:59:29 + 0000]"The GET/HTTP / 1.1"200, 612,"-" "Curl / 7.29.0" "-"
test- nginx. 2. Drsv2s4cnf9y @ manager | 10.0.0.2 - [25 / Mar 2021:14:59:32 + 0000]"The GET/HTTP / 1.1"200, 612,"-" "Curl / 7.29.0" "-"
Copy the codeAt this point all requests are loaded onto the three back-end Nginx services.
The end of the
How swarm can replace the functions of microservices!
Qq group: 869215239 Search: coding on the way to focus on the public number!