245 lines
10 KiB
Markdown
245 lines
10 KiB
Markdown
# Upgrading PostgreSQL for Auto DevOps
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Auto DevOps provides an [in-cluster PostgreSQL database](customize.md#postgresql-database-support)
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for your application.
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The version of the chart used to provision PostgreSQL:
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- Is 0.7.1 in GitLab 12.8 and earlier.
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- Can be set to from 0.7.1 to 8.2.1 in GitLab 12.9 and later.
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GitLab encourages users to migrate their database to the newer PostgreSQL chart.
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This guide provides instructions on how to migrate your PostgreSQL database, which
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involves:
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1. Taking a database dump of your data.
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1. Installing a new PostgreSQL database using the newer version 8.2.1 of the chart
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and removing the old PostgreSQL installation.
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1. Restoring the database dump into the new PostgreSQL.
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## Prerequisites
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1. Install
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[`kubectl`](https://kubernetes.io/docs/tasks/tools/install-kubectl/).
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1. Ensure that you can access your Kubernetes cluster using `kubectl`.
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This varies based on Kubernetes providers.
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1. Prepare for downtime. The steps below include taking the application offline
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so that the in-cluster database does not get modified after the database dump is created.
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1. Ensure you have not set `POSTGRES_ENABLED` to `false`, as this setting deletes
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any existing channel 1 database. For more information, see
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[Detected an existing PostgreSQL database](index.md#detected-an-existing-postgresql-database).
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TIP: **Tip:**
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If you have configured Auto DevOps to have staging,
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consider trying out the backup and restore steps on staging first, or
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trying this out on a review app.
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## Take your application offline
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If required, take your application offline to prevent the database from
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being modified after the database dump is created.
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1. Get the Kubernetes namespace for the environment. It typically looks like `<project-name>-<project-id>-<environment>`.
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In our example, the namespace is called `minimal-ruby-app-4349298-production`.
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```shell
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$ kubectl get ns
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NAME STATUS AGE
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minimal-ruby-app-4349298-production Active 7d14h
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```
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1. For ease of use, export the namespace name:
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```shell
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export APP_NAMESPACE=minimal-ruby-app-4349298-production
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```
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1. Get the deployment name for your application with the following command. In our example, the deployment name is `production`.
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```shell
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$ kubectl get deployment --namespace "$APP_NAMESPACE"
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NAME READY UP-TO-DATE AVAILABLE AGE
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production 2/2 2 2 7d21h
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production-postgres 1/1 1 1 7d21h
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```
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1. To prevent the database from being modified, set replicas to 0 for the deployment with the following command.
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We use the deployment name from the previous step (`deployments/<DEPLOYMENT_NAME>`).
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```shell
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$ kubectl scale --replicas=0 deployments/production --namespace "$APP_NAMESPACE"
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deployment.extensions/production scaled
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```
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1. You also will need to set replicas to zero for workers if you have any.
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## Backup
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1. Get the service name for PostgreSQL. The name of the service should end with `-postgres`. In our example the service name is `production-postgres`.
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```shell
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$ kubectl get svc --namespace "$APP_NAMESPACE"
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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production-auto-deploy ClusterIP 10.30.13.90 <none> 5000/TCP 7d14h
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production-postgres ClusterIP 10.30.4.57 <none> 5432/TCP 7d14h
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```
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1. Get the pod name for PostgreSQL with the following command. In our example, the pod name is `production-postgres-5db86568d7-qxlxv`.
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```shell
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$ kubectl get pod --namespace "$APP_NAMESPACE" -l app=production-postgres
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NAME READY STATUS RESTARTS AGE
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production-postgres-5db86568d7-qxlxv 1/1 Running 0 7d14h
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```
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1. Connect to the pod with:
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```shell
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kubectl exec -it production-postgres-5db86568d7-qxlxv --namespace "$APP_NAMESPACE" bash
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```
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1. Once, connected, create a dump file with the following command.
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- `SERVICE_NAME` is the service name obtained in a previous step.
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- `USERNAME` is the username you have configured for PostgreSQL. The default is `user`.
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- `DATABASE_NAME` is usually the environment name.
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- You will be asked for the database password, the default is `testing-password`.
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```shell
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## Format is:
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# pg_dump -h SERVICE_NAME -U USERNAME DATABASE_NAME > /tmp/backup.sql
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pg_dump -h production-postgres -U user production > /tmp/backup.sql
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```
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1. Once the backup dump is complete, exit the Kubernetes exec process with `Control-D` or `exit`.
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1. Download the dump file with the following command:
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```shell
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kubectl cp --namespace "$APP_NAMESPACE" production-postgres-5db86568d7-qxlxv:/tmp/backup.sql backup.sql
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```
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## Retain persistent volumes
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By default the [persistent
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volumes](https://kubernetes.io/docs/concepts/storage/persistent-volumes/)
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used to store the underlying data for PostgreSQL is marked as `Delete`
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when the pods and pod claims that use the volume is deleted.
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This is significant as, when you opt into the newer 8.2.1 PostgreSQL, the older 0.7.1 PostgreSQL is
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deleted causing the persistent volumes to be deleted as well.
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You can verify this by using the following command:
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```shell
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$ kubectl get pv
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NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
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pvc-0da80c08-5239-11ea-9c8d-42010a8e0096 8Gi RWO Delete Bound minimal-ruby-app-4349298-staging/staging-postgres standard 7d22h
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pvc-9085e3d3-5239-11ea-9c8d-42010a8e0096 8Gi RWO Delete Bound minimal-ruby-app-4349298-production/production-postgres standard 7d22h
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```
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To retain the persistent volume, even when the older 0.7.1 PostgreSQL is
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deleted, we can change the retention policy to `Retain`. In this example, we find
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the persistent volume names by looking at the claims names. As we are
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interested in keeping the volumes for the staging and production of the
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`minimal-ruby-app-4349298` application, the volume names here are
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`pvc-0da80c08-5239-11ea-9c8d-42010a8e0096` and `pvc-9085e3d3-5239-11ea-9c8d-42010a8e0096`:
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```shell
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$ kubectl patch pv pvc-0da80c08-5239-11ea-9c8d-42010a8e0096 -p '{"spec":{"persistentVolumeReclaimPolicy":"Retain"}}'
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persistentvolume/pvc-0da80c08-5239-11ea-9c8d-42010a8e0096 patched
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$ kubectl patch pv pvc-9085e3d3-5239-11ea-9c8d-42010a8e0096 -p '{"spec":{"persistentVolumeReclaimPolicy":"Retain"}}'
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persistentvolume/pvc-9085e3d3-5239-11ea-9c8d-42010a8e0096 patched
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$ kubectl get pv
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NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
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pvc-0da80c08-5239-11ea-9c8d-42010a8e0096 8Gi RWO Retain Bound minimal-ruby-app-4349298-staging/staging-postgres standard 7d22h
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pvc-9085e3d3-5239-11ea-9c8d-42010a8e0096 8Gi RWO Retain Bound minimal-ruby-app-4349298-production/production-postgres standard 7d22h
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```
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## Install new PostgreSQL
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CAUTION: **Caution:**
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Using the newer version of PostgreSQL will delete
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the older 0.7.1 PostgreSQL. To prevent the underlying data from being
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deleted, you can choose to retain the [persistent volume](#retain-persistent-volumes).
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TIP: **Tip:**
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You can also
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[scope](../../ci/environments/index.md#scoping-environments-with-specs) the
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`AUTO_DEVOPS_POSTGRES_CHANNEL`, `AUTO_DEVOPS_POSTGRES_DELETE_V1` and
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`POSTGRES_VERSION` variables to specific environments, e.g. `staging`.
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1. Set `AUTO_DEVOPS_POSTGRES_CHANNEL` to `2`. This opts into using the
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newer 8.2.1-based PostgreSQL, and removes the older 0.7.1-based
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PostgreSQL.
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1. Set `AUTO_DEVOPS_POSTGRES_DELETE_V1` to a non-empty value. This flag is a
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safeguard to prevent accidental deletion of databases.
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1. Set `POSTGRES_VERSION` to `11.7`. This is the minimum PostgreSQL
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version supported.
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1. Set `PRODUCTION_REPLICAS` to `0`. For other environments, use
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`REPLICAS` with an [environment scope](../../ci/environments/index.md#scoping-environments-with-specs).
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1. If you have set the `DB_INITIALIZE` or `DB_MIGRATE` variables, either
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remove the variables, or rename the variables temporarily to
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`XDB_INITIALIZE` or the `XDB_MIGRATE` to effectively disable them.
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1. Run a new CI pipeline for the branch. In this case, we run a new CI
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pipeline for `master`.
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1. Once the pipeline is successful, your application will now be upgraded
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with the new PostgreSQL installed. There will also be zero replicas
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which means no traffic will be served for your application (to prevent
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new data from coming in).
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## Restore
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1. Get the pod name for the new PostgreSQL, in our example, the pod name is
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`production-postgresql-0`:
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```shell
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$ kubectl get pod --namespace "$APP_NAMESPACE" -l app=postgresql
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NAME READY STATUS RESTARTS AGE
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production-postgresql-0 1/1 Running 0 19m
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````
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1. Copy the dump file from the backup steps to the pod:
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```shell
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kubectl cp --namespace "$APP_NAMESPACE" backup.sql production-postgresql-0:/tmp/backup.sql
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```
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1. Connect to the pod:
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```shell
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kubectl exec -it production-postgresql-0 --namespace "$APP_NAMESPACE" bash
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```
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1. Once connected to the pod, run the following command to restore the database.
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- You will be asked for the database password, the default is `testing-password`.
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- `USERNAME` is the username you have configured for PostgreSQL. The default is `user`.
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- `DATABASE_NAME` is usually the environment name.
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```shell
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## Format is:
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# psql -U USERNAME -d DATABASE_NAME < /tmp/backup.sql
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psql -U user -d production < /tmp/backup.sql
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```
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1. You can now check that your data restored correctly after the restore
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is complete. You can perform spot checks of your data by using the
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`psql`.
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## Reinstate your application
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Once you are satisfied the database has been restored, run the following
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steps to reinstate your application:
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1. Restore the `DB_INITIALIZE` and `DB_MIGRATE` variables, if previously
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removed or disabled.
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1. Restore the `PRODUCTION_REPLICAS` or `REPLICAS` variable to its original value.
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1. Run a new CI pipeline for the branch. In this case, we run a new CI
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pipeline for `master`. After the pipeline is successful, your
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application should be serving traffic as before.
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