Upgrade Concourse with BOSH

Upgrading Concourse involves following these steps:

Download the latest supported Concourse release
Upload it to your BOSH environment
Create a new deployment manifest
Use BOSH to deploy this new manifest in place of your existing Concourse deployment

This step-by-step tutorial includes details for checking out sample manifest and supporting files for the desired deployment version from the concourse-bosh-deployment repository. These can be used as a template for customizing your release.

The guide below is written to provide necessary details for someone starting this process from scratch on a new workstation. You can skip certain steps if you have deployed from concourse-bosh-deployment before and already have a working directory, credentials, and/or cloud configuration variables.

If you have not backed up your current Concourse deployment, follow the steps in Back up Concourse before proceeding.

Set up the concourse-bosh-deployment Directory on Your Local Machine

Skip step 1 if you already have concourse-bosh-deployment cloned to a local directory.

Clone the concourse-bosh-deployment repository to your workstation by running the following command:
```
git clone https://github.com/concourse/concourse-bosh-deployment.git
```
Navigate to the concourse-bosh-deployment directory by running the following command:
```
cd concourse-bosh-deployment
```
All the paths used in this guide are relative to this directory.
VMware recommends checking your Git status whenever you enter the concourse-bosh-deployment directory. Do so by running the following command:
```
 git status
 
```
If you encounter unstaged files that can be overwritten by checking out the new release branch, `git stash` your changes, check out the release, and then `git stash pop` and resolve any merge conflicts.

Check out the concourse-bosh-deployment Git tag that corresponds to your desired upgrade version. For example, with the latest v6.7.3 release:

git checkout v6.7.3

Run git tag to see a list of the different releases.

Checking out a release, rather than a branch, produces the following output:

Note: checking out RELEASE.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, use `-b` with the checkout command again. For example:

  git checkout -b <new-branch-name>

HEAD is now at HASH COMMIT-MESSAGE

Where:

RELEASE is the release version number.

HASH is the hash key of the most recent commit.

COMMIT-MESSAGE is the most recent commit message.

Set up Certificates, Log in, and Alias your BOSH Environment

If you already have your CA certificate and have already logged in to and aliased your BOSH environment, you can skip this section.

Get a CA certificate for your BOSH Director.
1. If you created your BOSH Director manually, retrieve the credentials that were created during setup.
  
  If you are working with an Operations Manager-deployed BOSH Director, log in to Operations Manager and access the following endpoint in your Tanzu Operations Manager domain:
```
https://OPS-MANAGER-DOMAIN/download_root_ca_cert
```
  Where OPS-MANAGER-DOMAIN is the Operations Manager domain.
  
  This will create a file in your downloads folder called root_ca_certificate.
2. Copy and rename the root_ca_certificate file into the working directory. For example, on OSX:
```
mv ~/Downloads/root_ca_certificate ./ca-cert.crt
```
This certificate file can be used whenever a CLI command asks for a --ca-cert flag and value.
Ensure you are logged in to your BOSH environment with the appropriate BOSH Director credentials. For example, if you saved your CA certificate as ca-cert.crt, run the following command:
```
bosh -e BOSH-ENVIRONMENT-IP login --ca-cert=ca-cert.crt
```
Where BOSH-ENVIRONMENT-IP is your BOSH environment IP address.

If you set up a BOSH Director directly, the director credentials were returned as a file after the setup process finished.

If you have an Operations Manager-deployed BOSH Director, you can find the director credentials in the Operations Manager credentials tab or at the following endpoint in your Operations Manager domain:
```
http://OPS-MANAGER-DOMAIN/api/v0/deployed/director/credentials/director_credentials
```
Where OPS-MANAGER-DOMAIN is your Operations Manager domain.
Give your environment an alias by running the following command:
```
bosh -e BOSH-ENVIRONMENT-IP alias-env ALIAS --ca-cert=ca-cert.crt
```
Where:
- BOSH-ENVIRONMENT-IP is your BOSH environment IP address
- ALIAS is the alias you're creating BOSH environment
Using an alias for your BOSH environment substantially reduces the keystrokes needed for commands in future. You can use this alias whenever you target this environment by using the -e flag in a BOSH command.

BOSH and Concourse Variables

Deploying with BOSH requires setting some variables to fill in details in your manifest. These are written as placeholders in the following format: ((placeholder)).

You can do this in a number of ways, but VMware recommends creating a file to define a key-value pair for each required variable, and checking it into version control so that it can be maintained and tracked over time. Follow the steps below to do so.

The following steps describe setting variables that are necessary for deployment in a YAML file. If you prefer to set them on the command line when you run bosh deploy, you can pass them in at that time with the --var KEY=VALUE flag and syntax. For more information, see Deploy in the BOSH documentation.

To find the values needed to fill out each of the variables in the next step, check the currently deployed Concourse manifest. Use the following command to tell BOSH to fetch the manifest and put it in a deployed-manifest.yml file:
```
bosh \
-e BOSH-ENVIRONMENT-ALIAS \
-d CONCOURSE-DEPLOYMENT-NAME \
manifest > deployed-manifest.yml
```
Where:
- BOSH-ENVIRONMENT-ALIAS is your BOSH environment alias
- CONCOURSE-DEPLOYMENT-NAME is your Concourse deployment name.
This command produces a file that contains a value for each of the variables that you define in the next step.

Sending the response to a file is a security precaution that ensures that any included keys are not echoed to your terminal session history. Destroy this file after you are done with this upgrade process.
Create a file to store your Concourse- and BOSH-related environment variables, if you do not already have one from a previous deployment. For example, the following command uses Vim to create a file called variables.yml:
```
vim variables.yml
```
This file holds all the variables that BOSH needs to interpolate into references in the manifest file. The manifest file then serves as a recipe for the new deployment.

The benefit to creating a file for these variables is that you can check this file into your version control, track changes over time, and more easily document and share this information with others in your org. It also saves you the trouble of looking up configuration details every time you need to change your Concourse deployment.
Add the key-value pairs shown in the snippet below into the file.
```
---
local_user:
  username: USERNAME
  password: PASSWORD

deployment_name: DEPLOYMENT-NAME
db_persistent_disk_type: PERSISTENT-DISK-TYPE
db_vm_type: VM-TYPE
external_url: EXTERNAL-URL
network_name: NETWORK-NAME
postgres_password: POSTGRESQL-PASSWORD
web_ip: WEB-IP
web_network_name: WEB-NETWORK-NAME
web_vm_type: WEB-VM-TYPE
worker_vm_type: WORKER-VM-TYPE
azs: AVAILABILITY-ZONES
```
Where:

DEPLOYMENT-NAME is your deployment name

PERSISTENT-DISK-TYPE is the persistent disk type for the database

VM-TYPE is the VM type for the database instance

EXTERNAL-URL is the external URL

NETWORK-NAME is the name subproperty of the network property in your deployed manifest

POSTGRESQL-PASSWORD is the password subproperty of the PostgreSQL property in your deployed manifest

WEB-IP is your web IP

WEB-NETWORK-NAME is your web network name

WEB-VM-TYPE is the VM type for the web instance

WORKER-VM-TYPE is the VM type for the worker instance

AVAILABILITY-ZONES is the name of one of the azs in your cloud-config.yml file
Replace each value placeholder with the appropriate properties in the deployed-manifest.yml file that you created earlier.
(Optional): If Concourse is deployed with a component such as CredHub, these variables might be automatically interpolated. You can check if this is the case by running the following command:
```
 bosh \
 -e BOSH-ENVIRONMENT-ALIAS \
 -d TARGET-CONCOURSE-DEPLOYMENT \
 manifest | grep “(("
 
```
If the search returns any values, CredHub or a similar component might be involved. In this case, investigate your current deployment, or get in touch with whoever has the necessary context, before proceeding further.
Save and close your variables file.

Confirm your Availability Zones

Your deployed manifest, located at ./cluster/concourse.yml, has some defaults set for availability zones (AZs). Often these must be customized to suit a given environment. To ensure these are set correctly, follow these steps:

Check the AZ names in your currently deployed manifest.

To find these, you can reference the deployed-manifest.yml file we created in the last section, or run the bosh manifest command to re-create it:
```
bosh \
-e BOSH-ENVIRONMENT-ALIAS \
-d CONCOURSE-DEPLOYMENT-NAME \
manifest > deployed-manifest.yml
```
Open the Concourse manifest file of the concourse-bosh-deployment repository cluster by running the following command:
```
vim ./cluster/concourse.yml
```
Change each of the three az properties in the manifest file so that they match the AZs in your deployed-manifest.yml file. For example, if your AZ is default, your manifest file looks like this:
```
...
instance_groups:
- name: web
  ...
  azs: [default]
  ...

- name: db
  ...
  azs: [default]
  ...

- name: worker
  ...
  azs: [default]
  ...
...
```
You can use a find-and-replace operation in a text editor to change all these values simultaneously.
Save and close the ./cluster/concourse.yml file.

"bosh deploy" Concourse to your Cloud Environment

If you have many pipelines with many containers, pause your pipelines before you start the upgrade. Then, after you finish the upgrade, wait for all of your workers to be ready and then turn on your pipelines one by one. VMware recommends doing this to prevent your pipelines from overwhelming the first workers that come online, which could cause a crash.

To deploy your new Concourse version, you need the following information:

Your new concourse manifest, such as ./cluster/concourse.yml
Your versions file, such as -l versions.yml
Your environment variables, such as -l variables.yml
Any required operations files for your environment or Concourse setup
A --vars-store flag with the name of a file in which BOSH can store your cluster credentials, such as --vars-store cluster-creds.yml

BOSH creates the cluster-creds.yml file file for you if it does not already exist. If this is the case, you still need to specify a filename for BOSH to use. In the case that you already have a cluster-creds.yml file, specify it here so that BOSH does not re-create it. If you specify a file that does not exist, and BOSH re-creates this file for you, it also re-creates things such as passwords and secrets that exist in the file.

When you are ready, navigate to your terminal and run the following bosh deploy command:

bosh deploy \
-e BOSH-ENVIRONMENT-ALIAS \
-d CONCOURSE-DEPLOYMENT-NAME ./cluster/concourse.yml \
-l versions.yml \
-l variables.yml \
-o ./cluster/operations/backup-atc.yml \
-o ./cluster/operations/basic-auth.yml \
-o ./cluster/operations/privileged-http.yml \
-o ./cluster/operations/static-web.yml \
--vars-store cluster-creds.yml

Different Concourse deployments require different environment variables and operations files. If you encounter an error, check the error message for clues about additional variables that need to be set. For more information, see the Concourse documentation.