Create Swarm Service Locally

docker swarm init
Swarm initialized: current node (sj85xz6gexk9kkso65fptppjv) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-03w64skgdjczcl7dcmqsilyb8eaqvvhpkhqnmc0pvykstru5xa-8qo1i3qc7hw789y7appol2kni 192.168.65.2:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

• What we have now is a single node swarm with all the built-in functionality out of the box

What just happened? (docker swarm init)

• Lots of PKI and security automation

  • Root Signing Certificate created for our Swarm

  • Certificate is issued for first Manager node

  • Join tokens are created

• Raft Consensus database created to store root CA, configs and secrets

  • Encrypted by default on disk (1.13+)

  • No need for another key/value system to hold orchestration/secrets

  • Replicates logs amongst Managers via mutual TLS in "control plane"

Let's explore

~> docker node ls
ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS
sj85xz6gexk9kkso65fptppjv *   moby                Ready               Active              Leader

• Let's create a service

~> docker service create alpine ping 8.8.8.8
mxtjxv23zdmn7xtduhuci9ckz

~> docker service ls
ID                  NAME                MODE                REPLICAS            IMAGE               PORTS
mxtjxv23zdmn        confident_mclean    replicated          1/1                 alpine:latest

~>  docker service ps mxtjxv23zdmn   # this shows us containers
ID                  NAME                 IMAGE               NODE                DESIRED STATE       CURRENT STATE                 ERROR               PORTS
05ecxpe99oif        confident_mclean.1   alpine:latest       moby                Running             Running about a minute ago

~> docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS   NAMES
dba6938ae565        alpine:latest       "ping 8.8.8.8"      2 minutes ago       Up 2 minutes                confident_mclean.1.05ecxpe99oifzy3pmh94s3csa

• Let's scale our service

~> docker service update mxtjxv23zdmn --replicas 3
mxtjxv23zdmn

~> docker service ls
ID                  NAME                MODE                REPLICAS            IMAGE               PORTS
mxtjxv23zdmn        confident_mclean    replicated          3/3                 alpine:latest

docker service ps mxtjxv23zdmn
ID                  NAME                 IMAGE               NODE                DESIRED STATE       CURRENT STATE            ERROR               PORTS
05ecxpe99oif        confident_mclean.1   alpine:latest       moby                Running             Running 6 minutes ago
zkivho70qhy9        confident_mclean.2   alpine:latest       moby                Running             Running 2 minutes ago
ud0isohnx5vy        confident_mclean.3   alpine:latest       moby                Running             Running 2 minutes ago

• We now have running 3 tasks

• Let's remove/kill one of the running containers and see what happens

~> docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS   NAMES
2288215be2ae        alpine:latest       "ping 8.8.8.8"      5 minutes ago       Up 5 minutes                confident_mclean.3.ud0isohnx5vy50eomjjhad9yo
b6f1bf35be1e        alpine:latest       "ping 8.8.8.8"      5 minutes ago       Up 5 minutes                confident_mclean.2.zkivho70qhy9t4mg6d7kf94ue
dba6938ae565        alpine:latest       "ping 8.8.8.8"      9 minutes ago       Up 9 minutes                confident_mclean.1.05ecxpe99oifzy3pmh94s3csa

~> docker container rm -f 2288215be2ae
2288215be2ae

~> docker service ls
ID                  NAME                MODE                REPLICAS            IMAGE               PORTS
mxtjxv23zdmn        confident_mclean    replicated          2/3                 alpine:latest

~> docker service ls
ID                  NAME                MODE                REPLICAS            IMAGE               PORTS
mxtjxv23zdmn        confident_mclean    replicated          3/3                 alpine:latest

~> docker service ps mxtjxv23zdmn
ID                  NAME                     IMAGE               NODE                DESIRED STATE       CURRENT STATE                ERROR                         PORTS
ccfz80x50ztb        confident_mclean.1       alpine:latest       moby                Running             Running 41 seconds ago
05ecxpe99oif         \_ confident_mclean.1   alpine:latest       moby                Shutdown            Failed 48 seconds ago        "task: non-zero exit (137)"
zkivho70qhy9        confident_mclean.2       alpine:latest       moby                Running             Running 8 minutes ago
sohismj9iukc        confident_mclean.3       alpine:latest       moby                Running             Running 8 minutes ago

• docker service restarted the killed container and it keeps history of crashes in ps output

• now let's remove our service

~> docker service rm confident_mclean
confident_mclean

~> docker service ls
ID                  NAME                MODE                REPLICAS            IMAGE               PORTS

~> docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS   NAMES

~> docker container ls -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS   NAMES

External links

• Deploy services to a swarm