Docker part 4
High Availability: more than one server
why: if one server got deleted then other server will gives the app
(docker swarm one container copy multiple servers manage the worker node)
DOCKER SWARM:
- its an orchestration tool for containers.
- used to manage multiple containers on multiple servers.
- here we create a cluster (group of servers).
- in that cluster, we can create same container on multiple servers.
- here we have the manager node and worker node.
- manager node will create & distribute the container to worker nodes.
- worker node's main purpose is to maintain the container.
- without docker engine we cant create the cluster.
- Port: 2377
- worker node will join on cluster by using a token.
- manager node will give the token.
manager node we have create container ,it will distribute worker nodes, worker node to connect token required ,all worker node open the port 2377 then only it will work
Step1: We have create three servers, all servers need to install docker
Step2: Docker installation
root@dockerhost:~/docker#apt install docker.io -y
root@dockerhost:~/docker# docker --version
Docker version 27.5.1, build 27.5.1-0ubuntu3~24.04.2
Worker1:
root@ip-10-0-2-60:~# docker --version
Docker version 27.5.1, build 27.5.1-0ubuntu3~24.04.2
Worker2:
root@ip-10-0-2-62:~# docker --version
Docker version 27.5.1, build 27.5.1-0ubuntu3~24.04.2
Step2: in manger server run the command Docker swarm , get the token copy the token to all worker node ,it will manage all worker nodes
root@dockerhost:~/docker# docker swarm init
Swarm initialized: current node (8jt0pszkvuxlj24a0aatlmz8o) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-1b6ovsg5p0s5ceudu18596rj1yrcy3q82xeiilgovwwytzleiz-4x0nxqdzrp2yvzqv02qokiaba 10.0.2.61:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
Worker node1 :
root@ip-10-0-2-60:~# docker swarm join --token SWMTKN-1-1b6ovsg5p0s5ceudu18596rj1yrcy3q82xeiilgovwwytzleiz-4x0nxqdzrp2yvzqv02qokiaba 10.0.2.61:2377
This node joined a swarm as a worker.
Worker node2 :
root@ip-10-0-2-62:~# docker swarm join --token SWMTKN-1-1b6ovsg5p0s5ceudu18596rj1yrcy3q82xeiilgovwwytzleiz-4x0nxqdzrp2yvzqv02qokiaba 10.0.2.61:2377
This node joined a swarm as a worker.
After added token in workernode ,automatically active the worker node in manager node
root@dockerhost:~/docker# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
8jt0pszkvuxlj24a0aatlmz8o * dockerhost Ready Active Leader 27.5.1
gpmbxxqougicd8i0aob627ykf ip-10-0-2-60 Ready Active 27.5.1
8flw0oqw6xjzw9ot8y612s8k3 ip-10-0-2-62 Ready Active 27.5.1
Step3:
root@dockerhost:~/docker# docker run -itd --name container1 -p 81:80 vakatisubbu/movies:latest
0388dee24ec4b6533b9a533f2c0c8bae13e3d4cee33122e90e5f3d6ccef2da9b
Step4: when every create container in manage server automatically worker node created container
for that you need create first service
Note: individual containers are not going to replicate.
if we create a service then only containers will be distributed.
SERVICE: it's a way of exposing and managing multiple containers.
in service we can create copy of conatiners.
that container copies will be distributed to all the nodes.
service -- > containers -- > distributed to nodes
step5: remove the existing container
root@dockerhost:~/docker# docker rm 0388dee24ec4
0388dee24ec4
root@dockerhost:~/docker# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
Step6: Create service
root@dockerhost:~/docker# docker service create --name movies --replicas 3 -p 81:80 vakatisubbu/movies:latest
zrs0y900dk4pf2cptavq7jv1m
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service zrs0y900dk4pf2cptavq7jv1m converged
Automatically came to all worker nodes
Worker node 1
root@ip-10-0-2-60:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
9ddfec38443f vakatisubbu/movies:latest "/usr/sbin/apachectl…" 25 seconds ago Up 24 seconds movies.1.zrt2pageb1yawgsu3ikd54q21
Worker node 2
root@ip-10-0-2-62:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
882a20decb78 vakatisubbu/movies:latest "/usr/sbin/apachectl…" 54 seconds ago Up 53 seconds movies.2.n3se13cdty5jjtvt8dsw4s1xl
Step6:See now same application running all servers this is called high availability
Step7: docker service commands , it will work in manager node only
root@dockerhost:~/docker# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
vis3a3ilm480 gracious_taussig replicated 0/1 movies:latest
zrs0y900dk4p movies replicated 3/3 vakatisubbu/movies:latest *:81->80/tcp
root@dockerhost:~/docker# docker service inspect movies
root@dockerhost:~/docker# docker service ps movies
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
zrt2pageb1ya movies.1 vakatisubbu/movies:latest ip-10-0-2-60 Running Running 6 minutes ago
n3se13cdty5j movies.2 vakatisubbu/movies:latest ip-10-0-2-62 Running Running 6 minutes ago
t3z17nhvws8c movies.3 vakatisubbu/movies:latest dockerhost Running Running 6 minutes ago
For practice :
docker service scale movies=10 : to scale in the containers
docker service scale movies=3 : to scale out the containers
docker service rollback movies : to go previous state
docker service logs movies : to see the logs
If you are remove service automatically container removed in worker nodes also
docker service rm movies : to delete the services.
Step8:
Manager node :
root@dockerhost:~/docker# docker service create --name movies --replicas 3 -p 81:80 vakatisubbu/movies:latest
khzwkp7bezihktyo844qe7gmo
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service khzwkp7bezihktyo844qe7gmo converged
Step9: swarm is self healing , we will try to kill container in worker2
root@ip-10-0-2-62:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
62928f113c25 vakatisubbu/movies:latest "/usr/sbin/apachectl…" About a minute ago Up About a minute movies.3.9pr1bum3hjrfw9dpot3m5yq1k
root@ip-10-0-2-62:~# docker kill 62928f113c25
62928f113c25
root@ip-10-0-2-62:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
6c2a01a5299e vakatisubbu/movies:latest "/usr/sbin/apachectl…" 5 seconds ago Created movies.3.gszek2kff5ln97tbpsgr0la2m
62928f113c25 vakatisubbu/movies:latest "/usr/sbin/apachectl…" 2 minutes ago Exited (137) 5 seconds ago movies.3.9pr1bum3hjrfw9dpot3m5yq1k
Step10: but application still working
Step11: if kill also automatically immediately ,manager create new container .that is self healing
But We will use Kubernates , realtime not using much
Step12: commands for docker service
root@dockerhost:~# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
khzwkp7bezih movies replicated 3/3 vakatisubbu/movies:latest *:81->80/tcp
Node all work node information
root@dockerhost:~# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
8jt0pszkvuxlj24a0aatlmz8o * dockerhost Ready Active Leader 27.5.1
gpmbxxqougicd8i0aob627ykf ip-10-0-2-60 Ready Active 27.5.1
8flw0oqw6xjzw9ot8y612s8k3 ip-10-0-2-62 Ready Active 27.5.1
Particular node informration
root@dockerhost:~# docker inspect gpmbxxqougicd8i0aob627ykf
[
{
"ID": "gpmbxxqougicd8i0aob627ykf",
"Version": {
Step13: Need to remove node , first need down the worker node
worker1 you need entry this command
root@ip-10-0-2-60:~# docker swarm leave
Node left the swarm.
Manager need check the status of nodes ,See now down
root@dockerhost:~# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
8jt0pszkvuxlj24a0aatlmz8o * dockerhost Ready Active Leader 27.5.1
gpmbxxqougicd8i0aob627ykf ip-10-0-2-60 Down Active 27.5.1
8flw0oqw6xjzw9ot8y612s8k3 ip-10-0-2-62 Ready Active 27.5.1
After down you using rm command remove the node
root@dockerhost:~# docker node rm gpmbxxqougicd8i0aob627ykf
gpmbxxqougicd8i0aob627ykf
Run 'docker node COMMAND --help' for more information on a command.
root@dockerhost:~# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
8jt0pszkvuxlj24a0aatlmz8o * dockerhost Ready Active Leader 27.5.1
8flw0oqw6xjzw9ot8y612s8k3 ip-10-0-2-62 Ready Active 27.5.1
Step14: if want re add the node , just enter the command join token again in worknode,it will add automatically
Worker node
root@ip-10-0-2-60:~# docker swarm join --token SWMTKN-1-1b6ovsg5p0s5ceudu18596rj1yrcy3q82xeiilgovwwytzleiz-4x0nxqdzrp2yvzqv02qokiaba 10.0.2.61:2377
This node joined a swarm as a worker.
Manager node see readded
root@dockerhost:~# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
8jt0pszkvuxlj24a0aatlmz8o * dockerhost Ready Active Leader 27.5.1
fbpsc3hjqsh3sntv9g17c88jq ip-10-0-2-60 Ready Active 27.5.1
8flw0oqw6xjzw9ot8y612s8k3 ip-10-0-2-62 Ready Active 27.5.1
Purpose: Communicating two servers ,now not using kubertes
there is no autoscaling,load balancing not exist in docker swarm
DOCKER NETWORKING:
Docker networks are used to make communication between the multiple containers that are running on same or different docker hosts.
We have different types of docker networks.
Bridge Network : SAME HOST
Overlay network : DIFFERENT HOST
Host Network
None network
BRIDGE NETWORK: It is a default network that container will communicate with each other within the same host.(Two container communicating each other we use Bridge network same host)
OVERLAY NETWORK: Used to communicate containers with each other across the multiple docker hosts. (Two host servers ,communicate two different containers overlaynetwork)
HOST NETWORK: When you Want your container IP and ec2 instance IP same then you use host network
NONE NETWORK: When you don’t Want The container to get exposed to the world, we use none network. It will not provide any network to our container.
root@dockerhost:~# docker network ls
NETWORK ID NAME DRIVER SCOPE
38a9eb42edc7 bridge bridge local
bc0d91e098f7 docker_gwbridge bridge local
8797cf25d831 host host local
5fj7zbvzq7ft ingress overlay swarm
7fbb54dd8455 none null local
root@dockerhost:~#
Step1: Creating customize network
root@dockerhost:~# docker network create vakatisubbu
fefe5c82ecc3952a05fcf2795d4cc9218b206dcdd27531a7338a851c08dfbeaf
See her vakatisubbu own network create
root@dockerhost:~# docker network ls
NETWORK ID NAME DRIVER SCOPE
38a9eb42edc7 bridge bridge local
bc0d91e098f7 docker_gwbridge bridge local
8797cf25d831 host host local
5fj7zbvzq7ft ingress overlay swarm
7fbb54dd8455 none null local
fefe5c82ecc3 vakatisubbu bridge local
Details about network type , if any network default network type coming as bridge
root@dockerhost:~# docker service inspect vakatisubbu
[]
Status: Error: no such service: vakatisubbu, Code: 1
root@dockerhost:~# docker network inspect vakatisubbu
Step1: To change the bridge network default to custom network
Sample created one container
root@dockerhost:~# docker run -itd --name container1 ubuntu
Unable to find image 'ubuntu:latest' locally
latest: Pulling from library/ubuntu
32f112e3802c: Already exists
Digest: sha256:a08e551cb33850e4740772b38217fc1796a66da2506d312abe51acda354ff061
Status: Downloaded newer image for ubuntu:latest
13f93d4dd337b5dff463281118fff525fab8202e76361ab1725c97fac85ab4ea
root@dockerhost:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
13f93d4dd337 ubuntu "/bin/bash" 7 seconds ago Up 6 seconds container1
2767ee65764a vakatisubbu/movies:latest "/usr/sbin/apachectl…" 45 minutes ago Up 44 minutes movies.1.ddh2ltx74sct0zogr23dk3vdf
root@dockerhost:~# docker run -itd --name container2 ubuntu
6ecfa2faaef621a7e857b600fef7a34063bdf73e0ab5c4916d2a1a448c795b2a
root@dockerhost:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
6ecfa2faaef6 ubuntu "/bin/bash" 4 seconds ago Up 3 seconds container2
13f93d4dd337 ubuntu "/bin/bash" About a minute ago Up 59 seconds container1
2767ee65764a vakatisubbu/movies:latest "/usr/sbin/apachectl…" 45 minutes ago Up 45 minutes movies.1.ddh2ltx74sct0zogr23dk3vdf
Step2:
See by default network type Bridge, adding this into vakatisubbu bridge
root@dockerhost:~# docker inspect 6ecfa2faaef6
"NetworkSettings": {
"Bridge": "",
"SandboxID": "4dda7e27fff8832bdfc3700dc2d0ab388e90a3b136d7ba1869470e791eeb4dcc",
"SandboxKey": "/var/run/docker/netns/4dda7e27fff8",
"Ports": {},
root@dockerhost:~# docker network connect vakatisubbu container1
See now container added to network
root@dockerhost:~# docker network inspect vakatisubbu
"ConfigOnly": false,
"Containers": {
"13f93d4dd337b5dff463281118fff525fab8202e76361ab1725c97fac85ab4ea": {
"Name": "container1",
"EndpointID": "75fcb0f196865f7b9de577c9dff039777f9b829f802c0fbe71fc04bd57f2c242",
"MacAddress": "02:42:ac:13:00:02",
"IPv4Address": "172.19.0.2/16",
"IPv6Address": ""
}
},
"Options": {},
"Labels": {}
}
]
Step3: Now two container in same network
root@dockerhost:~# docker network connect vakatisubbu container2
root@dockerhost:~# docker network inspect vakatisubbu
"ConfigOnly": false,
"Containers": {
"13f93d4dd337b5dff463281118fff525fab8202e76361ab1725c97fac85ab4ea": {
"Name": "container1",
"EndpointID": "75fcb0f196865f7b9de577c9dff039777f9b829f802c0fbe71fc04bd57f2c242",
"MacAddress": "02:42:ac:13:00:02",
"IPv4Address": "172.19.0.2/16",
"IPv6Address": ""
},
"6ecfa2faaef621a7e857b600fef7a34063bdf73e0ab5c4916d2a1a448c795b2a": {
"Name": "container2",
"EndpointID": "18ad6846b64edeb8ae78b5943a18a2f48de7886e41331118f314cdbdfd878e2d",
"MacAddress": "02:42:ac:13:00:03",
"IPv4Address": "172.19.0.3/16",
"IPv6Address": ""
}
},
"Options": {},
"Labels": {}
}
]
Step4: Jenkins installation in docker , software get form the docker register hub
INSTALLING MULTIPLE TOOLS
docker run -it --name jenkins -p 8080:8080 jenkins/jenkins:lts
docker run -it --name prometheus-container -e TZ=UTC -p 9090:9090 prom/prometheus
docker run -d --name grafana -p 3000:3000 grafana/grafana
Below is the Docker architecture :
We have three component docker client ,docker host and docker registry
docker client(docker pull,docker push...), we will ask image client , if image not exist ,it will ask host ,if host not exist it will get the registry for the image os
Daemon is control all containers ,services and images
DATABASE SETUP
docker run -itd --name dbcont -e MYSQL_ROOT_PASSWORD=test123 mysql:8.0
docker exec -it dbcont bash
mysql -u root -p
--Database installed successfully.
bash-5.1# mysql --version
mysql Ver 8.0.43 for Linux on x86_64 (MySQL Community Server - GPL)
--Thanks
