# GitLab CI template for OpenShift

This project implements a GitLab CI/CD template to deploy your application to an [OpenShift](https://www.openshift.com/) platform.

## Usage

In order to include this template in your project, add the following to your `gitlab-ci.yml`:

```yaml
include:
  - project: 'to-be-continuous/openshift'
    ref: '3.1.0'
    file: '/templates/gitlab-ci-openshift.yml'
```

## Understand

This chapter introduces key notions and principle to understand how this template works.

### Managed deployment environments

This template implements continuous delivery/continuous deployment for projects hosted on OpenShift platforms.

#### Review environments

The template supports **review** environments: those are dynamic and ephemeral environments to deploy your
_ongoing developments_ (a.k.a. _feature_ or _topic_ branches).

When enabled, it deploys the result from upstream build stages to a dedicated and temporary environment.
It is only active for non-production, non-integration branches.

It is a strict equivalent of GitLab's [Review Apps](https://docs.gitlab.com/ee/ci/review_apps/) feature.

It also comes with a _cleanup_ job (accessible either from the _environments_ page, or from the pipeline view).

#### Integration environment

If you're using a Git Workflow with an integration branch (such as [Gitflow](https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow)),
the template supports an **integration** environment.

When enabled, it deploys the result from upstream build stages to a dedicated environment.
It is only active for your integration branch (`develop` by default).

#### Production environments

Lastly, the template supports 2 environments associated to your production branch (`master` by default):

* a **staging** environment (an iso-prod environment meant for testing and validation purpose),
* the **production** environment.

You're free to enable whichever or both, and you can also choose your deployment-to-production policy:

* **continuous deployment**: automatic deployment to production (when the upstream pipeline is successful),
* **continuous delivery**: deployment to production can be triggered manually (when the upstream pipeline is successful).

### Supported authentication methods

This template supports token authentication only.
Tokens associated with OpenShift user accounts are only valid for 24 hours.
To generate a token that never expires you need to create a new [service account](https://docs.openshift.com/container-platform/latest/authentication/understanding-and-creating-service-accounts.html).

Follow these steps:

```bash
oc create serviceaccount cicd
oc policy add-role-to-user <role_name> system:serviceaccount:<your_project_name>:cicd -n <your_project_name>
oc serviceaccounts get-token cicd
```

:warning: don't forget to replace `<your_project_name>` with your OpenShift project name and `<role_name>` with the appropriate role (ask your OpenShift support).

### Deployment context variables

In order to manage the various deployment environments, this template provides a couple of **dynamic variables**
that you might use in your hook scripts, deployment manifests and other deployment resources:

* `${environment_type}`: the current deployment environment type (`review`, `integration`, `staging` or `production`)
* `${environment_name}`: a generated application name to use for the current deployment environment (ex: `myproject-review-fix-bug-12` or `myproject-staging`) - _details below_
* `${environment_name_ssc}`: the above application name in [SCREAMING_SNAKE_CASE](https://en.wikipedia.org/wiki/Snake_case) format
    (ex: `MYPROJECT_REVIEW_FIX_BUG_12` or `MYPROJECT_STAGING`)

#### Generated environment name

The `${environment_name}` variable is generated to designate each deployment environment with a unique and meaningful application name.
By construction, it is suitable for inclusion in DNS, URLs, Kubernetes labels...
It is built from:

* the application _base name_ (defaults to `$CI_PROJECT_NAME` but can be overridden globally and/or per deployment environment - _see configuration variables_)
* GitLab predefined `$CI_ENVIRONMENT_SLUG` variable ([sluggified](https://en.wikipedia.org/wiki/Clean_URL#Slug) name, truncated to 24 characters)

The `${environment_name}` variable is then evaluated as:

* `<app base name>` for the production environment
* `<app base name>-$CI_ENVIRONMENT_SLUG` for all other deployment environments
* :bulb: `${environment_name}` can also be overriden per environment with the appropriate configuration variable

Examples (with an application's base name `myapp`):

| `$environment_type` | Branch        | `$CI_ENVIRONMENT_SLUG`  | `$environment_name` |
|---------------------|---------------|-------------------------|---------------------|
| `review`            | `feat/blabla` | `review-feat-bla-xmuzs6`| `myapp-review-feat-bla-xmuzs6` |
| `integration`       | `develop`     | `integration`           | `myapp-integration` |
| `staging`           | `main`        | `staging`               | `myapp-staging` |
| `production`        | `main`        | `production`            | `myapp` |

### Supported deployment methods

The OpenShift template supports two ways of deploying your code:

1. script-based deployment,
2. template-based deployment.

#### 1: script-based deployment

In this mode, you only have to provide a shell script that fully implements the deployment using the [`oc` CLI](https://docs.openshift.com/container-platform/latest/cli_reference/openshift_cli/developer-cli-commands.html).

The deployment script is searched as follows:

1. look for a specific `os-deploy-$environment_type.sh` in the `$OS_SCRIPTS_DIR` directory in your project (e.g. `os-deploy-staging.sh` for staging environment),
2. if not found: look for a default `os-deploy.sh` in the `$OS_SCRIPTS_DIR` directory in your project,
3. if not found: the GitLab CI template assumes you're using the template-based deployment policy.

#### 2: template-based deployment

In this mode, you have to provide a [OpenShift templates](https://docs.openshift.com/container-platform/latest/openshift_images/using-templates.html)
in your project structure, and let the GitLab CI template `oc apply` it.

The template processes the following steps:

1. _optionally_ executes the `os-pre-apply.sh` script in your project to perform specific environment pre-initialization (for e.g. create required services),
2. looks for your OpenShift [template](https://docs.openshift.com/container-platform/latest/openshift_images/using-templates.html) file, performs [variables substitution](#using-variabless) and [`oc apply`](https://docs.openshift.com/container-platform/latest/cli_reference/openshift_cli/developer-cli-commands.html#oc-apply) it,
    1. look for a specific `openshift-$environment_type.yml` in your project (e.g. `openshift-staging.yml` for staging environment),
    2. fallbacks to default `openshift.yml`.
3. _optionally_ executes the `os-post-apply.sh` script in your project to perform specific environment post-initialization stuff,
4. _optionally_ executes the `os-readiness-check` to wait & check for the application to be ready (if not found, the template assumes the application was successfully started).

Deployment jobs process the selected template with the following [labels](https://docs.openshift.com/container-platform/latest/openshift_images/using-templates.html#writing-labels):

* `app`: the application target name to use in this environment (i.e. `$environment_name`)<br/>
   _Can be overridden with `$OS_APP_LABEL`._
* `env`: the environment type  (i.e. `$environment_type_`)<br/>
   _Can be overridden with `$OS_ENV_LABEL`._

### Cleanup jobs

The GitLab CI template for OpenShift supports two policies for destroying an environment (actually only review environments):

1. script-based cleanup
2. template-based cleanup

#### 1: script-based cleanup

In this mode, you only have to provide a shell script that fully implements the environment cleanup using the [`oc` CLI](https://docs.openshift.com/container-platform/latest/cli_reference/openshift_cli/developer-cli-commands.html).

The a deployment script is searched as follows:

1. look for a specific `os-cleanup-$environment_type.sh` in the `$OS_SCRIPTS_DIR` directory in your project (e.g. `os-cleanup-staging.sh` for staging environment),
2. if not found: look for a default `os-cleanup.sh` in the `$OS_SCRIPTS_DIR` directory in your project,
3. if not found: the GitLab CI template assumes you're using the template-based cleanup policy.

> TIP: a nice way to implement environment cleanup is to declare the label `app=${environment_name}` on every OpenShift 
> object associated to your environment.
> Then environment cleanup can be implemented very easily with command `oc delete all,pvc,is,secret -l "app=${environment_name}"`

#### 2: template-based cleanup

In this mode, you mainly let OpenShift delete all objects from your OpenShift deployment file.

The template processes the following steps:

1. _optionally_ executes the `os-pre-cleanup.sh` script in your project to perform specific environment pre-cleanup stuff,
2. [deletes](https://docs.openshift.com/container-platform/latest/cli_reference/openshift_cli/developer-cli-commands.html#oc-delete) **all** objects with label `app=${environment_name}`<br/>
   _works well with template-based deployment as this label is forced during `oc apply`_
3. _optionally_ executes the `os-post-cleanup.sh` script in your project to perform specific environment post-cleanup (for e.g. delete bound services).

#### Cleanup job limitations

When using this template, you have to be aware of one limitation (bug) with the cleanup job.

By default, the cleanup job triggered automatically on branch deletion will **fail** due to not being able
to fetch the Git branch prior to executing the job (sounds obvious as the branch was just deleted).
This is pretty annoying, but as you may see above, deleting an env _may_ require scripts from the project...

So, what can be done about that?

1. if your project doesn't require any delete script (in other words deleting all objects with label `app=${environment_name}` is
   enough to clean-up everything): you could simply override the cleanup job Git strategy to prevent from fetching the
   branch code:
   ```yaml
   os-cleanup-review:
     variables:
       GIT_STRATEGY: none
   ```
2. in any other case, we're just sorry about this bug, but there is not much we can do:
    * remind to delete your review env **manually before deleting the branch**
    * otherwise you'll have to do it afterwards from your computer (using `oc` CLI) or from the OpenShift console.

### Using variables

You have to be aware that your deployment (and cleanup) scripts have to be able to cope with various environments, each 
with different application names, exposed routes, settings, ...
Part of this complexity can be handled by the lookup policies described above (ex: one script/manifest per env) and also 
by using available environment variables:

1. [deployment context variables](#deployment-context-variables) provided by the template:
    * `${environment_type}`: the current environment type (`review`, `integration`, `staging` or `production`)
    * `${environment_name}`: the application name to use for the current environment (ex: `myproject-review-fix-bug-12` or `myproject-staging`)
    * `${environment_name_ssc}`: the application name in [SCREAMING_SNAKE_CASE](https://en.wikipedia.org/wiki/Snake_case) format
       (ex: `MYPROJECT_REVIEW_FIX_BUG_12` or `MYPROJECT_STAGING`)
    * `${hostname}`: the environment hostname, extracted from the current environment url (after late variable expansion - see below)
2. any [GitLab CI variable](https://docs.gitlab.com/ee/ci/variables/predefined_variables.html)
3. any [custom variable](https://docs.gitlab.com/ee/ci/variables/#add-a-cicd-variable-to-a-project)
    (ex: `${SECRET_TOKEN}` that you have set in your project CI/CD variables)

While your scripts may simply use any of those variables, your [OpenShift templates](https://docs.openshift.com/container-platform/latest/openshift_images/using-templates.html)
shall be variabilized using [parameters](https://docs.openshift.com/container-platform/latest/openshift_images/using-templates.html#templates-writing-parameters_using-templates).

Parameters are evaluated in the following order:

1. from a (optional) specific `openshift-$environment_type.env` file found in the `$OS_SCRIPTS_DIR` directory of your project,
2. from the (optional) default `openshift.env` file found in the `$OS_SCRIPTS_DIR` directory of your project,
3. from the [environment](#using-variables) (either predefined GitLab CI, custom or dynamic variables).

For example, with the following parameters in your template:

```yaml
parameters:
  - name: environment_name
    description: "the application target name to use in this environment (provided by GitLab CI template)"
    required: true
  - name: hostname
    description: "the environment hostname (provided by GitLab CI template)"
    required: true
  - name: MEMORY
    description: "Pod memory (depends on the environment)"
    required: true
  - name: INSTANCES
    description: "Number of pods (depends on the environment)"
    required: true
  - name: SECRET_TOKEN
    description: "A secret that should not be managed in Git !"
    required: true
```

With a default `openshift.env` file:

```dotenv
INSTANCE=1
MEMORY=2Gi
```

And a specific `openshift-production.env` file:

```dotenv
INSTANCE=3
```

And finally `SECRET_TOKEN` variable defined in your project CI/CD variables.

Then, when deploying to `production`, the parameters will be evaluated as follows:

| Parameter      | Evaluated from                                |
| -------------- | --------------------------------------------- |
| `environment_name`      | dynamic variable set by the deployment script |
| `hostname`     | dynamic variable set by the deployment script |
| `MEMORY`       | default `openshift.env` file (undefined in specific `openshift-production.env` file) |
| `INSTANCES`    | specific `openshift-production.env` file      |
| `SECRET_TOKEN` | project CI/CD variables                       |

#### About multi-line parameters

The template manages multiline parameters passed through [environment](#using-variables) (ex: a TLS certificate
in PEM format).

Unfortunately it doesn't support multiline parameters from dotenv files (OpenShift limitation), but you might use the
following technique.

Exemple in your default `openshift.env` file:

```dotenv
# define SSL_CERT template param using a GitLab CI secret variable
TLS_CERT=${DEV_TLS_CERT}
```

We could imagine the `openshift-production.env` as follows:

```dotenv
# define SSL_CERT template param using a GitLab CI secret variable
TLS_CERT=${PROD_TLS_CERT}
```

The template will take care of expanding variables contained in your dotenv files (requires `DEV_TLS_CERT` and
`PROD_TLS_CERT` are defined in your [environment](#using-variables)).

### Environments URL management

The OpenShift template supports two ways of providing your environments url:

* a **static way**: when the environments url can be determined in advance, probably because you're exposing your routes through a DNS you manage,
* a [**dynamic way**](https://docs.gitlab.com/ee/ci/environments/#set-dynamic-environment-urls-after-a-job-finishes): when the url cannot be known before the
  deployment job is executed.

The **static way** can be implemented simply by setting the appropriate configuration variable(s) depending on the environment (see environments configuration chapters):

* `$OS_ENVIRONMENT_URL` to define a default url pattern for all your envs,
* `$OS_REVIEW_ENVIRONMENT_URL`, `$OS_INTEG_ENVIRONMENT_URL`, `$OS_STAGING_ENVIRONMENT_URL` and `$OS_PROD_ENVIRONMENT_URL` to override the default.

> :information_source: Each of those variables support a **late variable expansion mechanism** with the `%{somevar}` syntax, 
> allowing you to use any dynamically evaluated variables such as `${environment_name}`.
>
> Example:
>
> ```yaml
> variables:
>   OS_BASE_APP_NAME: "wonderapp"
>   # global url for all environments
>   OS_ENVIRONMENT_URL: "https://%{environment_name}.nonprod.acme.domain"
>   # override for prod (late expansion of $OS_BASE_APP_NAME not needed here)
>   OS_PROD_ENVIRONMENT_URL: "https://$OS_BASE_APP_NAME.acme.domain"
>   # override for review (using separate resource paths)
>   OS_REVIEW_ENVIRONMENT_URL: "https://wonderapp-review.nonprod.acme.domain/%{environment_name}"
> ```

To implement the **dynamic way**, your deployment script shall simply generate a `environment_url.txt` file in the working directory, containing only
the dynamically generated url. When detected by the template, it will use it as the newly deployed environment url.

### Deployment output variables

Each deployment job produces _output variables_ that are propagated to downstream jobs (using [dotenv artifacts](https://docs.gitlab.com/ee/ci/pipelines/job_artifacts.html#artifactsreportsdotenv)):

* `$environment_type`: set to the type of environment (`review`, `integration`, `staging` or `production`),
* `$environment_name`: the application name (see below),
* `$environment_url`: set to the environment URL (whether determined statically or dynamically).

Those variables may be freely used in downstream jobs (for instance to run acceptance tests against the latest deployed environment).

## Configuration reference

### Secrets management

Here are some advices about your **secrets** (variables marked with a :lock:):

1. Manage them as [project or group CI/CD variables](https://docs.gitlab.com/ee/ci/variables/#add-a-cicd-variable-to-a-project):
    * [**masked**](https://docs.gitlab.com/ee/ci/variables/#mask-a-cicd-variable) to prevent them from being inadvertently
      displayed in your job logs,
    * [**protected**](https://docs.gitlab.com/ee/ci/variables/#protected-cicd-variables) if you want to secure some secrets
      you don't want everyone in the project to have access to (for instance production secrets).
2. In case a secret contains [characters that prevent it from being masked](https://docs.gitlab.com/ee/ci/variables/#mask-a-cicd-variable),
  simply define its value as the [Base64](https://en.wikipedia.org/wiki/Base64) encoded value prefixed with `@b64@`:
  it will then be possible to mask it and the template will automatically decode it prior to using it.
3. Don't forget to escape special characters (ex: `$` -> `$$`).

### Global configuration

The OpenShift template uses some global configuration used throughout all jobs.

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `OS_CLI_IMAGE`           | the Docker image used to run OpenShift Client (OC) CLI commands <br/>:warning: **set the version required by your OpenShift server** | `quay.io/openshift/origin-cli:latest` |
| `OS_URL`                 | Default OpenShift API url              | **has to be defined** |
| :lock: `OS_TOKEN`        | Default OpenShift API [token](#supported-authentication-methods) | **has to be defined** |
| `OS_BASE_APP_NAME`       | Base application name                  | `$CI_PROJECT_NAME` ([see GitLab doc](https://docs.gitlab.com/ee/ci/variables/predefined_variables.html)) |
| `OS_ENVIRONMENT_URL`    | Default environments url _(only define for static environment URLs declaration)_<br/>_supports late variable expansion (ex: `https://%{environment_name}.openshift.acme.com`)_ | _none_ |
| `OS_SCRIPTS_DIR`         | directory where OpenShift scripts (templates, hook scripts) are located | `.` _(root project dir)_ |
| `OS_BASE_TEMPLATE_NAME`  | Base OpenShift template name           | `openshift` |
| `OS_APP_LABEL`           | The OpenShift [label](https://docs.openshift.com/container-platform/latest/openshift_images/using-templates.html#writing-labels) set with the `$environment_name` [dynamic variable](#using-variables) value. _Advanced usage_ | `app` |
| `OS_ENV_LABEL`           | The OpenShift [label](https://docs.openshift.com/container-platform/latest/openshift_images/using-templates.html#writing-labels) set with the `$environment_type` [dynamic variable](#using-variables) value (`review`, `integration`, `staging` or `prod`). _Advanced usage_ | `env` |

### Review environments configuration

Review environments are dynamic and ephemeral environments to deploy your _ongoing developments_ (a.k.a. _feature_ or 
_topic_ branches).

They are **disabled by default** and can be enabled by setting the `OS_REVIEW_PROJECT` variable (see below).

Here are variables supported to configure review environments:

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `OS_REVIEW_PROJECT`      | OpenShift [project](https://docs.openshift.com/container-platform/3.11/architecture/core_concepts/projects_and_users.html#projects) for `review` env | _none_ (disabled) |
| `OS_REVIEW_URL`          | OpenShift API url for `review` env  _(only define if different from default)_    | `$OS_URL` |
| :lock: `OS_REVIEW_TOKEN` | OpenShift API [token](#supported-authentication-methods) for `review` env  _(only define if different from default)_    | `$OS_TOKEN` |
| `OS_REVIEW_APP_NAME`     | Application name for `review` env      | `"${OS_BASE_APP_NAME}-${CI_ENVIRONMENT_SLUG}"` (ex: `myproject-review-fix-bug-12`) |
| `OS_REVIEW_ENVIRONMENT_URL`| The review environments url _(only define for static environment URLs declaration and if different from default)_ | `$OS_ENVIRONMENT_URL` |

Note: By default, review `environment.url` will be built as `${OS_REVIEW_ENVIRONMENT_SCHEME}://${$CI_PROJECT_NAME}-${CI_ENVIRONMENT_SLUG}.${OS_REVIEW_ENVIRONMENT_DOMAIN}`

### Integration environment configuration

The integration environment is the environment associated to your integration branch (`develop` by default).

It is **disabled by default** and can be enabled by setting the `OS_INTEG_PROJECT` variable (see below).

Here are variables supported to configure the integration environment:

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `OS_INTEG_PROJECT`       | OpenShift [project](https://docs.openshift.com/container-platform/3.11/architecture/core_concepts/projects_and_users.html#projects) for `integration` env | _none_ (disabled) |
| `OS_INTEG_URL`           | OpenShift API url for `integration` env  _(only define if different from default)_    | `$OS_URL` |
| :lock: `OS_INTEG_TOKEN`  | OpenShift API [token](#supported-authentication-methods) for `integration` env  _(only define if different from default)_    | `$OS_TOKEN` |
| `OS_INTEG_APP_NAME`      | Application name for `integration` env | `${OS_BASE_APP_NAME}-integration` |
| `OS_INTEG_ENVIRONMENT_URL`| The integration environment url _(only define for static environment URLs declaration and if different from default)_ | `$OS_ENVIRONMENT_URL` |

### Staging environment configuration

The staging environment is an iso-prod environment meant for testing and validation purpose associated to your production branch (`master` by default).

It is **disabled by default** and can be enabled by setting the `OS_STAGING_PROJECT` variable (see below).

Here are variables supported to configure the staging environment:

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `OS_STAGING_PROJECT`     | OpenShift [project](https://docs.openshift.com/container-platform/3.11/architecture/core_concepts/projects_and_users.html#projects) for `staging` env | _none_ (disabled) |
| `OS_STAGING_URL`         | OpenShift API url for `staging` env  _(only define if different from default)_   | `$OS_URL` |
| :lock: `OS_STAGING_TOKEN`| OpenShift API [token](#supported-authentication-methods) for `staging` env  _(only define if different from default)_    | `$OS_TOKEN` |
| `OS_STAGING_APP_NAME`    | Application name for `staging` env     | `${OS_BASE_APP_NAME}-staging` |
| `OS_STAGING_ENVIRONMENT_URL`| The staging environment url _(only define for static environment URLs declaration and if different from default)_ | `$OS_ENVIRONMENT_URL` |

### Production environment configuration

The production environment is the final deployment environment associated with your production branch (`master` by default).

It is **disabled by default** and can be enabled by setting the `OS_PROD_PROJECT` variable (see below).

Here are variables supported to configure the production environment:

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `OS_PROD_PROJECT`        | OpenShift [project](https://docs.openshift.com/container-platform/3.11/architecture/core_concepts/projects_and_users.html#projects) for `production` env | _none_ (disabled) |
| `OS_PROD_URL`            | OpenShift API url for `production` env  _(only define if different from default)_| `$OS_URL` |
| :lock: `OS_PROD_TOKEN`   | OpenShift API [token](#supported-authentication-methods) for `production` env  _(only define if different from default)_    | `$OS_TOKEN` |
| `OS_PROD_APP_NAME`       | Application name for `production` env  | `$OS_BASE_APP_NAME` |
| `OS_PROD_ENVIRONMENT_URL`| The production environment url _(only define for static environment URLs declaration and if different from default)_ | `$OS_ENVIRONMENT_URL` |
| `OS_PROD_DEPLOY_STRATEGY`| Defines the deployment to production strategy. One of `manual` (i.e. _one-click_) or `auto`. | `manual` |


### `os-cleanup-all-review` job

This job allows destroying all review environments at once (in order to save cloud resources).

It is **disabled by default** and can be controlled using the `$CLEANUP_ALL_REVIEW` variable:

1. automatically executed if `$CLEANUP_ALL_REVIEW` set to `force`,
2. manual job enabled from any `master` branch pipeline if `$CLEANUP_ALL_REVIEW` set to `true` (or any other value),

The first value `force` can be used in conjunction with a [scheduled](https://docs.gitlab.com/ee/ci/pipelines/schedules.html)
pipeline to cleanup cloud resources for instance everyday at 6pm or on friday evening.

The second one simply enables the (manual) cleanup job on the `master` branch pipeline.

Anyway destroyed review environments will be automatically re-created the next time a developer pushes a new commit on a
feature branch.

:warning: in case of scheduling the cleanup, you'll probably have to create an almost empty branch without any other
template (no need to build/test/analyse your code if your only goal is to cleanup environments).

### Extra functions

The template provides extra scripts that can be called in your `.gitlab-ci.yml` or hook scripts for extra treatments.

|  Function signature               |   Description                             |
|------------------------------------|-------------------------------------------|
| `force_rollout <deploymentConfig_name>` | Force a new rollout of the specified deploymentConfig. This can be useful when your deployment references a `stable` or `latest`image stream tag that is updated by gitlab pipeline. Once your template applied, if you only changed some application stuff and pushed a new version of the image, yet did not change anything in your template, no rollout will be triggered. Call this function to force a new rollout. |
| `poll_last_rollout <deploymentConfig_name>, [timeout: 2 minutes]` | Wait for the last rollout to end. This function will fail if the rollout fails or did not ended during the specified amount of time (two minutes by default). |
| `purge_old_image_tags <image_name>, <number_to_keep>` | For the given image stream, crawls all the tags and keeps only the `N` youngest ones. This can be useful when you create a new image tag for each pipeline (exemple of tag: `$CI_COMMIT_SHORT_SHA` or `$CI_COMMIT_SHA`). |

## Variants

### Vault variant

This variant allows delegating your secrets management to a [Vault](https://www.vaultproject.io/) server.

#### Configuration

In order to be able to communicate with the Vault server, the variant requires the additional configuration parameters:

| Name              | description                            | default value     |
| ----------------- | -------------------------------------- | ----------------- |
| `TBC_VAULT_IMAGE` | The [Vault Secrets Provider](https://gitlab.com/to-be-continuous/tools/vault-secrets-provider) image to use (can be overridden) | `$CI_REGISTRY/to-be-continuous/tools/vault-secrets-provider:master` |
| `VAULT_BASE_URL`  | The Vault server base API url          | _none_ |
| `VAULT_OIDC_AUD`  | The `aud` claim for the JWT | `$CI_SERVER_URL` |
| :lock: `VAULT_ROLE_ID`   | The [AppRole](https://www.vaultproject.io/docs/auth/approle) RoleID | **must be defined** |
| :lock: `VAULT_SECRET_ID` | The [AppRole](https://www.vaultproject.io/docs/auth/approle) SecretID | **must be defined** |

#### Usage

Then you may retrieve any of your secret(s) from Vault using the following syntax:

```text
@url@http://vault-secrets-provider/api/secrets/{secret_path}?field={field}
```

With:

| Name                             | description                            |
| -------------------------------- | -------------------------------------- |
| `secret_path` (_path parameter_) | this is your secret location in the Vault server |
| `field` (_query parameter_)      | parameter to access a single basic field from the secret JSON payload |

#### Example

```yaml
include:
  # main template
  - project: 'to-be-continuous/openshift'
    ref: '3.1.0'
    file: '/templates/gitlab-ci-openshift.yml'
  # Vault variant
  - project: 'to-be-continuous/openshift'
    ref: '3.1.0'
    file: '/templates/gitlab-ci-openshift-vault.yml'

variables:
    # audience claim for JWT
    VAULT_OIDC_AUD: "https://vault.acme.host"
    # Secrets managed by Vault
    OS_TOKEN: "@url@http://vault-secrets-provider/api/secrets/b7ecb6ebabc231/my-app/openshift/noprod?field=token"
    OS_PROD_TOKEN: "@url@http://vault-secrets-provider/api/secrets/b7ecb6ebabc231/my-app/openshift/noprod?field=token"
    VAULT_BASE_URL: "https://vault.acme.host/v1"
    # $VAULT_ROLE_ID and $VAULT_SECRET_ID defined as a secret CI/CD variable
```

## Examples

### Back-end application

#### Context

* review & staging environments enabled on Kermit no prod,
* production environment enabled on Kermit prod,
* implements automated acceptance (functional) tests: manual on review env, auto on staging.

#### `.gitlab-ci.yml`

```yaml
include:
  - project: 'to-be-continuous/openshift'
    ref: '3.1.0' 
    file: '/templates/gitlab-ci-openshift.yml'

variables:
  OS_URL: "https://openshift-noprod.acme.host" # noprod cluster is default (review & staging)
  OS_PROD_URL: "https://openshift-prod.acme.host/" # prod cluster for prod env only
  # OS_TOKEN and OS_PROD_TOKEN are defined as a protected project variable
  OS_REVIEW_PROJECT: "myproj-noprod" # activates 'review' env in CI pipeline
  OS_STAGING_PROJECT: "myproj-noprod" # activates 'staging' env in CD pipeline
  OS_PROD_PROJECT: "myproj"
  OS_REVIEW_ENVIRONMENT_DOMAIN: "apps-noprod.acme.host" # intranet route
  OS_STAGING_ENVIRONMENT_URL: "https://myproj-staging.apps-noprod.acme.host" # internet route
  OS_PROD_ENVIRONMENT_URL: "https://myproj.apps.acme.com" # internet route


# Pipeline steps
stages:
  - build
  - test
  - deploy
  - acceptance
  - production
```

#### OpenShift template

```yaml
# This generic template instantiates all required OpenShift objects
# It uses the following parameters that will be dynamically replaced by the deployment script:
# - ${environment_name}
# - ${environment_name_ssc}
# - ${hostname}
# - ${environment_name}
apiVersion: v1
kind: Template
metadata:
  name: my-application-template
  description: an OpenShift template for my application
# template parameters
parameters:
  - name: environment_name
    description: "the application target name to use in this environment (provided by GitLab CI template)"
    required: true
  - name: environment_name_ssc
    description: "the application target name in SCREAMING_SNAKE_CASE format (provided by GitLab CI template)"
    required: true
  - name: hostname
    description: "the environment hostname (provided by GitLab CI template)"
    required: true
  - name: docker_image
    description: "the Docker image build in upstream stages (provided by the Docker template)"
    required: true
objects:
# === Service
- apiVersion: v1
  kind: Service
  metadata:
    annotations:
      description: Exposes and load balances the application pods.
    labels:
      app: ${environment_name}
    name: ${environment_name}
  spec:
    ports:
    - name: http
      port: 8080
      protocol: TCP
      targetPort: 8080
    selector:
      app: ${environment_name}
# === DeploymentConfig
- apiVersion: apps.openshift.io/v1
  kind: DeploymentConfig
  metadata:
    annotations:
      description: The deployment configuration of application.
    labels:
      app: ${environment_name}
    name: ${environment_name}
  spec:
    replicas: 1
    revisionHistoryLimit: 2
    selector:
      app: ${environment_name}
    strategy:
      type: Rolling
      rollingParams:
        timeoutSeconds: 3600
    template:
      metadata:
        labels:
          app: ${environment_name}
      spec:
        containers:
        - image: ${docker_image}
          imagePullPolicy: Always
          name: spring-boot
          ports:
          - containerPort: 8080
            name: http
            protocol: TCP
          securityContext:
            privileged: false
    triggers:
    - type: ConfigChange
# === Route
- apiVersion: route.openshift.io/v1
  kind: Route
  metadata:
    annotations:
      description: The route exposes the service at a hostname.
    labels:
      app: ${environment_name}
    name: ${environment_name}
  spec:
    host: ${hostname}
    port:
      targetPort: 8080
    to:
      kind: Service
      name: ${environment_name}
```

#### hook scripts

##### `os-post-apply.sh`

This script - when found by the template - is executed **after** running `oc apply`, to perform specific environment
post-initialization (for e.g. start build).

```bash
#!/bin/bash

set -e

# create a source-to-image binary build if does not exist
oc get buildconfig "$environment_name" 2> /dev/null || oc new-build openshift/redhat-openjdk18-openshift:1.4 --binary="true" --name="$environment_name" --labels="app=$environment_name"

# prepare build resources
mkdir -p target/openshift/deployments && cp target/my-application-1.0.0-SNAPSHOT.jar target/openshift/deployments/

# trigger build: this will trigger a deployment
oc start-build "$environment_name" --from-dir=target/openshift --wait --follow

# example for force_rollout
force_rollout $environment_name
```

##### `os-readiness-check.sh`

This script - when found by the template - is used to wait & check for the application to be ready.

It uses the template variable `$environment_url` to build absolute urls to the application.

It is supposed to exit with  status 0 on success (the template will go on with deployment), or any non-0 value in case
of error (the template will stop and as much as possible revert the ongoing deployment).

```bash
#!/bin/bash
for attempt in {1..20}
do
    echo "Testing application readiness ($attempt/20)..."
    if wget --no-check-certificate -T 2 --tries 1 "$environment_url/healthcheck"
    then
        echo "[INFO] healthcheck response: OK"
        exit 0
    fi
    sleep 5
done

echo "[ERROR] max attempts reached: failed"
exit 1
```