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4-Container-Group-Scaling-and-Recoverability.md

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Lab 4: Container Group Scaling and Recoverability

Difficulty: Intermediate

Time: 20 minutes

Tasks:

Prerequisites

Prior to running this lab, you must have completed the pre-reqs.

Task 1: Upload Docker Image to Bluemix

  1. Use the Container namespace in subsequent tasks.
  $ export CONTAINER_NAMESPACE=$(cf ic namespace get)
  1. Upload the Docker image from the Docker public registry to Bluemix as we did earlier using the following command.
  $ cf ic cpi ragsns/spring-boot registry.ng.bluemix.net/$CONTAINER_NAMESPACE/spring-boot
Sending build context to Docker daemon 2.048 kB
Step 0 : FROM ragsns/spring-boot
---> d8dc5ff8d27b
Successfully built d8dc5ff8d27b
The push refers to a repository [registry.ng.bluemix.net/ragsns/spring-boot] (len: 1)
d8dc5ff8d27b: Image already exists 
3565bce48566: Image already exists 
bc1666c40f44: Image already exists 
b6ac4efa6931: Image already exists 
d7c80008ad18: Image already exists 
de4a13c84f53: Image already exists 
97424a07faef: Image already exists 
f9194a57b559: Image already exists 
48a0ef800175: Image already exists 
3a7cffa50930: Image already exists 
0c24696b360d: Image already exists 
696be707a6b0: Image already exists 
2c00a767497d: Image already exists 
dc921aeac8d0: Image already exists 
4c0cc976b7bb: Image already exists 
1d6f63d023f5: Image already exists 
ef2704e74ecc: Image already exists 
Digest: sha256:8a450a05521481b3df8c052f84c1888a7bc1406b0ee2b4ab0146d4dede043c0c

Task 2: Create a Container Recovery Group

  1. Create a Container Recovery Group with 3 (at least greater than 1) instances and port 8080 exposed with the following command.
$ cf ic group create  -p 8080 --name spring-boot --hostname spring-boot-$CONTAINER_NAMESPACE --domain mybluemix.net --memory 512 --max 3 --desired 3 --auto registry.ng.bluemix.net/$CONTAINER_NAMESPACE/spring-boot
Create group in progress
Created group spring-boot (id: 123dbe80-8ae8-434c-ba79-33a64aa82636)
Minimum container instances: 0
Maximum container instances: 3
Desired container instances: 3
  1. Verify the group was created with the following command. Eventually the status will show CREATE_COMPLETE.
$ cf ic group list
Group Id                             Name                                Status                              Created                             Updated                             Port
123dbe80-8ae8-434c-ba79-33a64aa82636 spring-boot                         CREATE_COMPLETE                     2015-11-20T16:38:33Z                                                    8080
  1. Inspect the group with the following command.
$ cf ic group inspect spring-boot
{
  "Autorecovery": "true", 
  "Cmd": [], 
  "Creation_time": "2015-12-14T16:39:12Z", 
  "Env": [
      "sgroup_name=spring-boot", 
      "metrics_target=logmet.opvis.bluemix.net:9095", 
      "logging_password=", 
      "tagseparator=_", 
      "tenant_id=49911e9c-cf3e-4913-9e20-ff52ed6d34e3", 
      "space_id=49911e9c-cf3e-4913-9e20-ff52ed6d34e3", 
      "logstash_target=logmet.opvis.bluemix.net:9091", 
      "sgroup_id=241262d9-90a4-4764-bf0a-c48ef8e13b36", 
      "tagformat=tenant_id group_id uuid", 
      "group_id=241262d9-90a4-4764-bf0a-c48ef8e13b36", 
      "metadata_hidden_hostname=instance-00122559"
  ], 
  "Id": "241262d9-90a4-4764-bf0a-c48ef8e13b36", 
  "Image": "6128feda-2f27-442c-a962-8859a43ee69e", 
  "Memory": 512, 
  "Name": "spring-boot", 
  "NumberInstances": {
      "CurrentSize": 3, 
      "Desired": 3, 
      "Max": 3, 
      "Min": 0
  }, 
  "Port": 8080, 
  "Route_Status": {
      "in_progress": false, 
      "message": "registered route successfully", 
      "successful": true
  }, 
  "Routes": [
      "spring-boot-ragsns.mybluemix.net"
  ], 
  "Status": "CREATE_COMPLETE", 
  "Updated_time": null
}

Task 3: Verify Scalability

There is a web service endpoint /env that we will invoke now as below.

  1. List all the environment variables associated with the application using the following command.
$ curl -L spring-boot-$CONTAINER_NAMESPACE.mybluemix.net/env
Environment : 
tenant_id = 49911e9c-cf3e-4913-9e20-ff52ed6d34e3
PATH = /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
DOCKER_WAITFORNET = true
sgroup_id = 241262d9-90a4-4764-bf0a-c48ef8e13b36
logstash_target = logmet.opvis.bluemix.net:9091
logging_password = 
tagformat = tenant_id group_id uuid
CA_CERTIFICATES_JAVA_VERSION = 20140324
TERM = xterm
LANG = C.UTF-8
uuid = 66ad3b7c-de2d-4707-a7a8-f894302e52e7
metrics_target = logmet.opvis.bluemix.net:9095
sgroup_name = spring-boot
HOSTNAME = instance-0010b64e
JAVA_DEBIAN_VERSION = 8u66-b17-1~bpo8+1
group_id = 241262d9-90a4-4764-bf0a-c48ef8e13b36
tagseparator = _
PWD = /
JAVA_VERSION = 8u66
space_id = 49911e9c-cf3e-4913-9e20-ff52ed6d34e3
HOME = /root
  1. We are primarily interested in the HOSTNAME. A container recovery group automatically creates a load balancer and load balances amongst these different instances. If you invoke the command repeatedly you must see as many different instances as the size of the container recovery group and no more (in this case three).
$ curl -L spring-boot-$CONTAINER_NAMESPACE.mybluemix.net/env | grep HOSTNAME
HOSTNAME = instance-000abaec

$ curl -L spring-boot-$CONTAINER_NAMESPACE.mybluemix.net/env | grep HOSTNAME
HOSTNAME = instance-00122559

```

$ curl -L spring-boot-$CONTAINER_NAMESPACE.mybluemix.net/env | grep HOSTNAME HOSTNAME = instance-0010b64e

You will start to see the same instances recycle after a while depending on how the load balancer balances the load.

$ curl -L spring-boot-$CONTAINER_NAMESPACE.mybluemix.net/env | grep HOSTNAME HOSTNAME = instance-00122559


## Task 4: Verify Recoverability

1. Verify that the instances are still running with the following command.

$ cf ic group instances spring-boot Container Id Name Group Image Created Updated State Private IP Port 1dc25949-b438-475b-8a63-40fab21b2700 sp-hwuf-wqvsqk7ywu3v-xs6i2dvhrutr-server-nh33si6nzus7 spring-boot registry.ng.bluemix.net/ragsns/spring-boot:latest 2016-02-03 10:05:16 -0500 EST Running 172.30.0.222 8080 b140192a-620c-4ba0-9d82-53822cb56f21 sp-hwuf-rbnbi734lsw7-4qukjqwpvfaf-server-34z3y46o3o6t spring-boot registry.ng.bluemix.net/ragsns/spring-boot:latest 2016-02-01 10:22:32 -0500 EST Running 172.30.0.173 8080 66ad3b7c-de2d-4707-a7a8-f894302e52e7 sp-hwuf-gdh2kugrqbez-6g3x7aumtnk5-server-aj2czsn3ntak spring-boot registry.ng.bluemix.net/ragsns/spring-boot:latest 2016-01-23 00:35:17 -0500 EST Running 172.30.0.167 8080


2. We will stop one of the containers either using the container Id or by issuing a command as below which will extract the container ID of the last container.

$ cf ic rm --force $(cf ic group instances spring-boot | tail -1 | awk '{print $1}') 66ad3b7c-de2d-4707-a7a8-f894302e52e7


3. Invoking the command immediately after deleting an instance should show that there is an instance (which is about to be recovered) that is not running or showing status as `DELETED`.

cf ic group instances spring-boot Container Id Name Group Image Created Updated State Private IP Port 1dc25949-b438-475b-8a63-40fab21b2700 sp-hwuf-wqvsqk7ywu3v-xs6i2dvhrutr-server-nh33si6nzus7 spring-boot registry.ng.bluemix.net/ragsns/spring-boot:latest 2016-02-03 10:05:16 -0500 EST Running 172.30.0.222 8080 b140192a-620c-4ba0-9d82-53822cb56f21 sp-hwuf-rbnbi734lsw7-4qukjqwpvfaf-server-34z3y46o3o6t spring-boot registry.ng.bluemix.net/ragsns/spring-boot:latest 2016-02-01 10:22:32 -0500 EST Running 172.30.0.173 8080 66ad3b7c-de2d-4707-a7a8-f894302e52e7 sp-hwuf-gdh2kugrqbez-6g3x7aumtnk5-server-aj2czsn3ntak spring-boot registry.ng.bluemix.net/ragsns/spring-boot:latest 2016-01-23 00:35:17 -0500 EST Deleted 8080

Running the command again should show that the instance has been deleted.

cf ic group instances spring-boot
Container Id Name Group Image Created Updated State Private IP Port 1dc25949-b438-475b-8a63-40fab21b2700 sp-hwuf-wqvsqk7ywu3v-xs6i2dvhrutr-server-nh33si6nzus7 spring-boot registry.ng.bluemix.net/ragsns/spring-boot:latest 2016-02-03 10:05:16 -0500 EST Running 172.30.0.222 8080 b140192a-620c-4ba0-9d82-53822cb56f21 sp-hwuf-rbnbi734lsw7-4qukjqwpvfaf-server-34z3y46o3o6t spring-boot registry.ng.bluemix.net/ragsns/spring-boot:latest 2016-02-01 10:22:32 -0500 EST Running 172.30.0.173 8080



4. After a while, you will notice that a container was just restarted (as in 13 minutes ago) compared with the other containers (that were started a day or more ago).

$ cf ic ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

1dc25949-b43 registry.ng.bluemix.net/ragsns/spring-boot:latest "" 13 minutes ago Running 13 minutes ago 8080/tcp sp-hwuf-wqvsqk7ywu3v-xs6i2dvhrutr-server-nh33si6nzus7 b140192a-620 registry.ng.bluemix.net/ragsns/spring-boot:latest "" 47 hours ago Running a day ago 8080/tcp sp-hwuf-rbnbi734lsw7-4qukjqwpvfaf-server-34z3y46o3o6t b5676e3f-c42 registry.ng.bluemix.net/ragsns/spring-boot:latest "" 11 days ago Running 11 days ago 8080/tcp sp-hwuf-gdh2kugrqbez-6g3x7aumtnk5-server-aj2czsn3ntak


5. If you re-run the command to get the `HOSTNAME` of the container, it now cycles between three container IDs but with a new instance ID (`instance-0012673b`) as below.

$ curl -L spring-boot-$CONTAINER_NAMESPACE.mybluemix.net/env | grep HOSTNAME HOSTNAME = instance-0012673b

$ curl -L spring-boot-$CONTAINER_NAMESPACE.mybluemix.net/env | grep HOSTNAME HOSTNAME = instance-00122559

  ```
$ curl -L spring-boot-$CONTAINER_NAMESPACE.mybluemix.net/env | grep HOSTNAME
HOSTNAME = instance-0010b64e

Cleanup

To continue with another lab, you need to clean up your container group. This can be done through the UI and the DELETE button on each container, or you can do this through the CLI with the following command

$ cf ic group rm -f spring-boot

##Congratulations!!! You have successfully accomplished Lab 4.

####Let's recap what you've accomplished thus far in this lab:

  • Created a Container Group
  • Verified scalability and load balancing of the container instances in the group
  • Verified recoverability by forcibly deleting an instance and noticing that another instance gets recreated.

##If you are still feeling ambitious, you can test zero downtime upgrades to a Cloud Foundry app.