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Example of Swarm Mode: Testing Simple Web Application
Raw
gistfile1.txt
Setup:
ajeetsraina81@ucp-1:~$ sudo docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS
8szgdxh310tkad373ourepch8 worker5 Ready Active
e2xjlg4610mmyym98sk91qu43 worker1 Ready Active
is52hxuxlrcclwd6hbujvflao worker2 Ready Active
nnnofsbqqbprgp4m4tw2oh2z1 worker4 Ready Active
sv2uuuy3spbh9oriue0mnyx83 * ucp-1 Ready Active Leader
sx1c598mlz6r6hg6zrbamrpsn worker3 Ready Active
Frontend: SimpleWeb
Backend: Redis
================================================
Example: Demonstrating How Load Balancing Works?
==master==>sudo docker network create -d overlay collabnet
j5ioa811szddvo1qo27lq76o7
==master==>sudo docker service create --name backend-db --network collabnet redis
ywmmezbehzj23nxid061p3w2g
==master==>sudo docker service ls
ID NAME MODE REPLICAS IMAGE
ywmmezbehzj2 backend-db replicated 0/1 redis:latest
==master==>sudo docker service ls
ID NAME MODE REPLICAS IMAGE
ywmmezbehzj2 backend-db replicated 1/1 redis:latest
==master==>sudo docker service create --name frontend --network collabnet --publish 80:80/tcp yeasy/simple-web
58nm866cjhw7oudw8b7tu0ryc
==master==>sudo docker service ls
ID NAME MODE REPLICAS IMAGE
58nm866cjhw7 frontend replicated 0/1 yeasy/simple-web:latest
ywmmezbehzj2 backend-db replicated 1/1 redis:latest
==master==>sudo docker service ls
ID NAME MODE REPLICAS IMAGE
58nm866cjhw7 frontend replicated 0/1 yeasy/simple-web:latest
ywmmezbehzj2 backend-db replicated 1/1 redis:latest
==master==>sudo docker service ls
ID NAME MODE REPLICAS IMAGE
58nm866cjhw7 frontend replicated 0/1 yeasy/simple-web:latest
ywmmezbehzj2 backend-db replicated 1/1 redis:latest
==master==>sudo docker service ls
ID NAME MODE REPLICAS IMAGE
58nm866cjhw7 frontend replicated 1/1 yeasy/simple-web:latest
ywmmezbehzj2 backend-db replicated 1/1 redis:latest
==master==>sudo curl http://localhost
<!DOCTYPE html> <html> <body><center><h1><font color="blue" face="Georgia, Arial" size=8><em>Real</em></font> Visit
Results</h1></center><p style="font-size:150%" >#2016-12-24 11:06:11: <font color="red">1</font> requests from &lt
<font color="blue">10.255.0.7</font>&gt to WebServer &lt<font color="blue">10.0.0.5</font>&gt</p><p style="font-siz
e:150%" >#2016-12-24 11:06:11: <font color="red">1</font> requests from &lt<font color="blue">LOCAL: 10.255.0.3</fo
nt>&gt to WebServer &lt<font color="blue">10.0.0.5</font>&gt</p></body> </html>==master==>
==master==>sudo docker system df
TYPE TOTAL ACTIVE SIZE RECLAIMABLE
Images 1 1 676.2 MB 0 B (0%)
Containers 1 1 47.98 kB 0 B (0%)
Local Volumes 0 0 0 B 0 B
==master==>sudo docker system df -v
Images space usage:
REPOSITORY TAG IMAGE ID CREATED SIZE SHARED SIZE
UNIQUE SIZE CONTAINERS
<none> <none> 46e5f91fc9a9 36 hours ago 676.2 MB 0 B
676.2 MB 1
Containers space usage:
CONTAINER ID IMAGE COMM
AND LOCAL VOLUMES SIZE CREATED STATUS NAMES
deef3d8af6b8 yeasy/simple-web@sha256:806adeaf8f5a5cf1ae7ff01493f556dfc24865e6efd4d52fad6e9b7437c0f169 "/bi
n/sh -c 'pytho..." 0 48 kB 4 minutes ago Up 4 minutes frontend.1.9ec
d3fj5gtmfxrrf2i5uqd5mj
Local Volumes space usage:
VOLUME NAME LINKS SIZE
==master==>
Example:3>
Frontend : Wordpress
Backend: MYSQL
======================================
Example:4>
Frontend:
Backend: MongoDB Sharding
Sharding is a method for distributing data across multiple machines. MongoDB uses sharding to support deployments with very large data sets and high throughput operations.
1 Master node
5 worker nodes
Master Node:
docker network create --driver overlay --opt encrypted mongoshard
sudo mkdir -p /opt/mongoshard/db-data
sudo chmod 777 /opt/mongoshard/db-data
Pull the mongodb.conf template from https://github.com/mongodb/mongo/blob/master/rpm/mongod.conf
File: mongodb.conf
=======================
# network interfaces
net:
port: 27017
# bindIp: 127.0.0.1 # Listen to local interface only, comment to listen on all interfaces.
#security:
#operationProfiling:
#replication:
sharding:
clusterRole: configsvr
## Enterprise-Only Options
...
=====================
We want one mongocfg on the main node (The main node will be the one that runs mongos).
$sudo docker service create -constraint "node.id==sv2uuuy3spbh9oriue0mnyx83" --mount type=bi
nd,src=/opt/mongoshard/db-data/,dst=/var/lib/mongodb/ --mount type=bind,src=/opt/mongoshard/mongodb.conf,dst=/etc/m
ongodb.conf --network mongoshard --name mongocfg1 --restart-condition on-failure --restart-max-attempts 3 --endpoin
t-mode dnsrr mongo:latest --config /etc/mongodb.conf
To try:
Now, from server1 (swarm leader) we can check nodes ids with the following command:
´´´
# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS
3ebujl8qci0pk2oiuww8p5us4 server3 Ready Active
7dt8zo3zrhj0m9tyvwq5yes5r server2 Ready Active
e4wiamxehzk4ramu1l9nntf9d * server1 Ready Active Leader
´´´
We want one mongocfg on the main node (The main node will be the one that runs mongos).
# docker service create --constraint "node.id==e4wiamxehzk4ramu1l9nntf9d" --mount type=bind,src=/opt/mongoshard/db-data/,dst=/var/lib/mongodb/ --mount type=bind,src=/opt/mongoshard/mongodb.conf,dst=/etc/mongodb.conf --network mongoshard --name mongocfg1 --restart-condition on-failure --restart-max-attempts 3 --endpoint-mode dnsrr mongo:latest --config /etc/mongodb.conf
9kpdd7bj445d3rh0g83ajm5j4
Now we need to create mongos. mongos is a service to redirect the queries to the different mongo shards.
It ships in the same docker package as mongodb, but it is a seperate executable.
We create a file called mongos with the following content:
´´´
FROM mongo:latest
ENTRYPOINT ["mongos"]
´´´
Then we create an image:
´´´
docker build -f mongos -t crimsonglory/mongos .
´´´
And we push it to our docker hub account:
´´´
docker login
´´´
Browse to hub.docker.com, login and create a repository.
´´´
docker push crimsonglory/mongos
´´´
We only have to do this once. or zero, you can use my crimsonglory/mongos hub.
# docker service create --constraint "node.id==e4wiamxehzk4ramu1l9nntf9d" --network mongoshard --name mongos1 --restart-condition on-failure --restart-max-attempts 3 -p 27017:27017 crimsonglory/mongos --configdb mongocfg1:27017
We use only 1 config server because Docker Swarm increases latency and using more config servers will only decrease performance.
(this last command may fail if you already have Mongo installed on the main node host. That's because the container can't bind to 27017 because its on use. You may want to change the 27017:27017 to 27018:27017 or something.)
Now the shards:
On each host that will be used for shards do:
´´´
mkdir /opt/mongoshard/db-shard/; chmod 777 /opt/mongoshard/db-shard
´´´
´´´
# docker service create --constraint "node.id==7dt8zo3zrhj0m9tyvwq5yes5r" --network mongoshard --name mongosh1 --restart-condition on-failure --restart-max-attempts 3 --mount type=bind,src=/opt/mongoshard/db-shard,dst=/var/lib/mongodb --mount type=bind,src=/opt/mongoshard/mongo-sh.conf,dst=/etc/mongod.conf --endpoint-mode dnsrr mongo:latest --config /etc/mongod.conf
1l6yx68fvvjy7x7713tlwgsy3
# docker service create --constraint "node.id==3ebujl8qci0pk2oiuww8p5us4" --network mongoshard --name mongosh2 --restart-condition on-failure --restart-max-attempts 3 --mount type=bind,src=/opt/mongoshard/db-shard,dst=/var/lib/mongodb --mount type=bind,src=/opt/mongoshard/mongo-sh.conf,dst=/etc/mongod.conf --endpoint-mode dnsrr mongo:latest --config /etc/mongod.conf
d0xxgmihl4u2ff23awbu90brt
´´´
Now tell mongos about the shards. We should be able to connect to mongos from outside the Docker container (because we map the port)
´´´
mongo 127.0.0.1:27017/admin
MongoDB shell version: 3.2.8
connecting to: 127.0.0.1:27017/admin
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
http://docs.mongodb.org/
Questions? Try the support group
http://groups.google.com/group/mongodb-user
Server has startup warnings:
2016-09-06T03:16:02.582+0000 I CONTROL [main] ** WARNING: You are running this process as the root user, which is not recommended.
2016-09-06T03:16:02.582+0000 I CONTROL [main]
mongos> sh.addShard("mongosh1")
{ "shardAdded" : "shard0000", "ok" : 1 }
mongos> sh.addShard("mongosh2")
{ "shardAdded" : "shard0001", "ok" : 1 }
mongos>
db.runCommand({"enablesharding": "DB_files"})
mongos> db.runCommand({"shardCollection": "DB_files.fs.chunks", "key": {"files_id": 1, "n": 1}, "numInitialChunks": 1000})
{ "collectionsharded" : "DB_files.fs.chunks", "ok" : 1 }
´´´
Not everything is perfect. With docker swarm mode (as 2016-10-05) we can't pass ulimit to the service. It's a pendding issue on docker repo.
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