postgres-release-training-exercice

README

postgres-release

---

This is a BOSH release for PostgreSQL.

Contents

• Deploying
• Customizing
• Contributing
• Known Limitation
• Upgrading

Deploying

In order to deploy the postgres-release you must follow the standard steps for deploying software with BOSH.

1. Deploy and run a BOSH director. Please refer to BOSH documentation for instructions on how to do that. Bosh-lite specific instructions can be found here.

2. Install the BOSH command line Interface (CLI) v2+. Please refer to BOSH CLI documentation. Use the CLI to target your director.

3. Upload the desired stemcell directly to bosh. bosh.io provides a resource to find and download stemcells.

   # Example for bosh-lite
   bosh upload-stemcell https://bosh.io/d/stemcells/bosh-warden-boshlite-ubuntu-xenial-go_agent
   

4. Upload the latest release from bosh.io:

   bosh upload-release https://bosh.io/d/github.com/cloudfoundry/postgres-release
   

   or create and upload a development release:

   cd ~/workspace/postgres-release
   bosh -n create-release --force && bosh -n upload-release
   

5. Generate the manifest. You can provide in input an operation file to customize the manifest:

   ~/workspace/postgres-release/scripts/generate-deployment-manifest \
   -o OPERATION-FILE-PATH > OUTPUT_MANIFEST_PATH
   

   You can use the operation file to specify postgres job properties or to override the configuration if your BOSH director cloud-config is not compatible.

   This example operation file is a great starting point. Note: when using this operation file, you will need to inject pgadmin_database_password at bosh deploy-time, which is a good pattern for keeping credentials out of manifests.

   You are also provided with options to enable TLS in the PostgreSQL server or to use static ips.

6. Deploy:

   bosh -d DEPLOYMENT_NAME deploy OUTPUT_MANIFEST_PATH
   

   Example, injecting the pgadmin_database_password variable:

   bosh -d DEPLOYMENT_NAME deploy -v pgadmin_database_password=foobarbaz OUTPUT_MANIFEST_PATH
   

Customizing

The table below shows the most significant properties you can use to customize your PostgreSQL installation. The complete list of available properties can be found in the spec.

Property	Description
databases.port	The database port. Default: 5432
databases.databases	A list of databases and associated properties to create when Postgres starts
databases.databases[n].name	Database name
databases.databases[n].citext	If true the citext extension is created for the db
databases.roles	A list of database roles and associated properties to create
databases.roles[n].name	Role name
databases.roles[n].password	Login password for the role. If not provided, TLS certificate authentication is assumed for the user.
databases.roles[n].common_name	The cn attribute of the certificate for the user. It only applies to TLS certificate authentication.
databases.roles[n].permissions	A list of attributes for the role. For the complete list of attributes, refer to ALTER ROLE command options.
databases.tls.certificate	PEM-encoded certificate for secure TLS communication
databases.tls.private_key	PEM-encoded key for secure TLS communication
databases.tls.ca	PEM-encoded certification authority for secure TLS communication. Only needed to let users authenticate with TLS certificate.
databases.max_connections	Maximum number of database connections
databases.log_line_prefix	The postgres printf style string that is output at the beginning of each log line. Default: %m:
databases.collect_statement_statistics	Enable the pg_stat_statements extension and collect statement execution statistics. Default: false
databases.additional_config	A map of additional key/value pairs to include as extra configuration properties
databases.monit_timeout	Monit timout in seconds for the postgres job start. Default: 90.
databases.trust_local_connection	Whether or not postgres must trust local connections. vcap is always trusted. It defaults to true.
databases.skip_data_copy_in_minor	Whether or not a copy of the data directory is created during PostgreSQL minor upgrades. A copy is created by default.
databases.hooks.timeout	Time limit in seconds for the hook script. By default, it's set to 0 that means no time limit.
databases.hooks.pre-start	Script to run before starting PostgreSQL.
databases.hooks.post-start	Script to run after PostgreSQL has started.
databases.hooks.pre-stop	Script to run before stopping PostgreSQL.
databases.hooks.post-stop	Script to run after PostgreSQL has stopped.
janitor.script	If specified, this script would be run periodically. This would be useful for running house-keeping tasks.
janitor.interval	Interval in seconds between two invocations of the janitor script. By default it's set to 1 day.
janitor.timeout	Time limit in seconds for the janitor script. By default it's set to 0 that means no time limit.

Note

• Removing a database from databases.databases list and deploying again does not trigger a physical deletion of the database in PostgreSQL.
• Removing a role from databases.roles list and deploying again does not trigger a physical deletion of the role in PostgreSQL.

Enabling TLS on the PostgreSQL server

PostgreSQL has native support for using TLS connections to encrypt client/server communications for increased security. You can enable it by setting the databases.tls.certificate and the databases.tls.private_key properties.

A script is provided that creates a CA, generates a key pair, and signs it with the CA:

./scripts/generate-postgres-certs -n HOSTNAME_OR_IP_ADDRESS

The common name for the server certificate must be set to the DNS hostname if any or to the ip address of the PostgreSQL server. This because in TLS mode verify-full, the hostname is matched against the common-name. Refer to PostgreSQL documentation for more details.

You can also use BOSH variables to generate the certificates. See by way of example the operation file used by the manifest generation script.

~/workspace/postgres-release/scripts/generate-deployment-manifest \
   -s -h HOSTNAME_OR_IP_ADDRESS \
   -o OPERATION-FILE-PATH > OUTPUT_MANIFEST_PATH

Enabling TLS certificate authentication

In order to perform authentication using TLS client certificates, you must not specify a user password and you must configure the following properties:

• databases.tls.certificate
• databases.tls.private_key
• databases.tls.ca

The cn (Common Name) attribute of the certificate will be compared to the requested database user name, and if they match the login will be allowed.

Optionally you can map the common_name to a different database user by specifying property databases.roles[n].common_name.

A script is provided that creates a client certificates:

./scripts/generate-postgres-client-certs --ca-cert <PATH-TO-CA-CERT> --ca-key <PATH-TO-CA-KEY> --client-name <USER_NAME>

Hooks

You can run custom code before or after PostgreSQL starts or stops or periodically. For details, see hooks documentation.

Backup and Restore

You can enable backup and restore through bbr by adding the bbr-postgres-db job with the postgres job and by setting its release_level_backup option to true. If enabled, a backup is collected using pg_dump for each database specified in the databases.databases property.

If you don't colocate the bbr-postgres-db with postgres then you must specify in the postgres.dbuser property a database user with enough permissions to run backup and restore.

If your PostgreSQL is configured with TLS, by default backup and restore are run with sslmode=verify-full. You can change it to sslmode=verify-ca by setting postgres.ssl_verify_hostname to false.

Caveats:

• Restore does not drop the database, the extensions, or the schema; therefore the schema of the restored and existing databases must be the same.
• If a backup is not present for one of the configured databases in the databases.databases property, the restore issues a message and continues.

Contributing

Contributor License Agreement

Contributors must sign the Contributor License Agreement before their contributions can be merged. Follow the directions here to complete that process.

Developer Workflow

1. Fork the repository and make a local clone

2. Create a feature branch from the development branch

   cd postgres-release
   git checkout develop
   git checkout -b feature-branch
   

3. Make changes on your branch

4. Test your changes by running acceptance tests

5. Push to your fork (git push origin feature-branch) and submit a pull request selecting develop as the target branch. PRs submitted against other branches will need to be resubmitted with the correct branch targeted.

Known Limitations

The postgres-release does not directly support high availability. Even if you deploy more instances, no replication is configured.

Upgrading

Refer to versions.yml in order to assess if a postgres-release version upgrades the PostgreSQL version.

Upgrade Test Policy

The maintainers of the postgres-release test the following upgrade paths:

• From the previous postgres-release
• From the latest postgres-release that bumps the previous PostgreSQL version
• From the latest cf-deployment that bumps the previous PostgreSQL version

Considerations before deploying

1. A copy of the database is made for the upgrade, you may need to adjust the persistent disk capacity of the postgres job.
   • For major upgrades the copy is always created
   • For minor upgrades the copy is created unless the databases.skip_data_copy_in_minor is set to true.
2. The upgrade happens as part of the pre-start and its duration may vary basing on your env.
   • In case of a PostgreSQL minor upgrade a simple copy of the old data directory is made.
   • In case of a PostgreSQL major upgrade the pg_upgrade utility is used.
3. Postgres will be unavailable during this upgrade.

Considerations after a successful deployment

In case a copy of the old database is kept (see considerations above), the old database is moved to /var/vcap/store/postgres/postgres-previous. The postgres-previous directory will be kept until the next postgres upgrade is performed in the future. You are free to remove this if you have verified the new database works and you want to reclaim the space.

Recovering a failure during deployment

In case of a long upgrade, the deployment may time out; anyway, bosh would not stop the actual upgrade process. In this case you can just wait for the upgrade to complete and, only when postgres is up and running, rerun the bosh deploy.

If the upgrade fails:

• The old data directory is still available at /var/vcap/store/postgres/postgres-x.x.x where x.x.x is the old PostgreSQL version
• The new data directory is at /var/vcap/store/postgres/postgres-y.y.y where y.y.y is the new PostgreSQL version
• If the upgrade is a PostgreSQL major upgrade:
  • A marker file is kept at /var/vcap/store/postgres/POSTGRES_UPGRADE_LOCK to prevent the upgrade from happening again.
  • pg_upgrade logs that may have details of why the migration failed can be found in /var/vcap/sys/log/postgres/postgres_ctl.log

If you want to attempt the upgrade again or to roll back to the previous release, you should remove the new data directory and, if present, the marker file.