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Finalize instructions

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Finalize the instructions in README.md

Signed-off-by: Scott Lowe <scott.lowe@scottlowe.org>
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Scott Lowe 2017-06-01 13:49:14 -06:00
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centos-atomic/docker-cloudinit/README.md
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# Instructions
# Using cloud-init to Customize Docker on CentOS Atomic Host
1. Capture the VPC ID of your default VPC using this command:
These files show an example of how to use `cloud-init` on a public cloud provider (AWS is used in this example) to customize the configuration and behavior of the Docker daemon on a CentOS Atomic Host instance.
VPC_ID=$(aws --output text ec2 describe-vpcs \
--filters Name=isDefault,Values="true" \
--query 'Vpcs[0].VpcId')
## Contents
2. Capture the subnet ID of one of the subnets (the first, by default) in the default VPC using this command (step 1 must be completed first):
* **cloud-config.yml**: This is the `cloud-init` configuration file that does the configuration of the Docker daemon on the instance. No modifications to this file should be necessary.
SN_ID=$(aws --output text ec2 describe-subnets \
--filters Name=vpc-id,Values="$VPC_ID" \
--query 'sort_by(Images,&AvailabilityZone)[0].SubnetId')
* **launch.sh**: This Bash shell script uses the AWS CLI to gather information from AWS and then launch an instance in your default VPC.
3. Capture the security group ID of a security group in the default VPC with the name "default" (it is assumed that this security group exists and allows SSH access to the instance; if this is not the case, you must fix this outside of this process):
* **README.md**: The file you're currently reading.
SG_ID=$(aws --output text ec2 describe-security-groups \
--filters Name=group-name,Values="default" \
Name=vpc-id,Values="$VPC_ID" \
--query 'SecurityGroups[0].GroupId')
## Prerequisites
4. Finally, capture the image ID of the latest version of the CentOS 7 Atomic Host AMI using this command:
Before you can use this environment, there are a few things you'll need to do:
IMAGE_ID=$(aws --output text ec2 describe-images \
--owners 410186602215 --filter Name=name,Values="*CentOS Atomic*" \
--query 'sort_by(Images,&CreationDate)[-1].ImageId')
1. You'll need to install **and** configure the AWS CLI. The launch script provided in this environment assumes that the AWS CLI is installed, configured, and working as expected.
5. Make sure you have an SSH key available to use with the instance and make note of the name of the SSH key.
2. In your default VPC, you'll need to either a) modify the default security group to allow inbound SSH; or b) create a security group called "default" that allows inbound SSH. If you prefer to use a name other than "default", you'll need to modify `launch.sh` with the updated name of the security group to use.
6. Launch an AWS instance using this command:
3. You'll need to have a working SSH keypair in AWS.
aws ec2 run-instances --image-id $IMAGE_ID --instance-type t2.micro \
--key-name keyname --user-data file://cloud-config.yml \
--subnet-id $SN_ID --security-group-ids $SG_ID
## Instructions
7. Connect to the instance using SSH.
1. If you are using a security group other than one named "default" (as described in the "Prerequisites" section), edit `launch.sh` and modify the command that looks up the security group ID accordingly.
8. Verify that the Docker daemon is listening over a network socket (not the default configuration) by running `ss -lnt` and/or running `docker` commands against the network socket (via `-H tcp://127.0.0.1:2375`).
2. Edit `launch.sh` to specify the correct AWS keypair to use when launching the instance.
3. Launch the instance using `./launch.sh`. This launch script assumes that the AWS CLI is working, and that the `cloud-config.yml` file is in the same directory.
4. Using the AWS CLI or the AWS Console, determine the public IP address assigned to the instance you just created.
5. Use SSH to connect to the instance (use the username "centos" to connect). Once logged into the instance, use `systemctl status docker.service` to verify that the Docker daemon is running and that the systemd drop-in located in `/etc/systemd/system/docker.service.d` has been loaded.
6. While logged into the instance, use `ss -lnt` to show that a process (the Docker daemon) is listening on TCP port 2375.
7. Verify the Docker daemon is working across the network by running `sudo docker -H tcp://127.0.0.1:2375 ps`.
Enjoy!
## License
This content is licensed under the MIT License.