# GitLab CI template for Google Cloud Platform

This project implements a GitLab CI/CD template to deploy your application to the [Google Cloud](https://cloud.google.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/gcloud'
    ref: '4.1.0'
    file: '/templates/gitlab-ci-gcloud.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 Google Cloud Platform.

It allows you to manage automatic deployment & cleanup of standard predefined environments.
Each environment can be enabled/disabled by configuration.
If you're not satisfied with predefined environments and/or their associated Git workflow, you may implement you own environments and
workflow, by reusing/extending the base (hidden) jobs. This is advanced usage and will not be covered by this documentation.

The following chapters present the managed predefined environments and their associated Git workflow.

#### 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` or `main` 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

The Google Cloud Platform template supports two kinds of authentication:

1. basic authentication with [Service Account key file](https://cloud.google.com/bigquery/docs/authentication/service-account-file),
2. or [federated authentication using OpenID Connect](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/).

#### Service account authentication

To use this authentication method, simply generate and provide [Service Account key file](https://cloud.google.com/bigquery/docs/authentication/service-account-file) as secret GitLab CI/CD variables (of type File), using the appropriate variables (see doc below).

Can be provided globally and/or per environment.

#### Federated authentication using OpenID Connect

The GCP template supports a [federated authentication using OpenID Connect](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/).

If you wish to use this authentication mode, please activate and configure the [OIDC variant](#oidc-variant). 

### 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: `myapp-review-fix-bug-12` or `myapp-staging`) - _details below_

#### 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` |

### Deployment and cleanup scripts

The Google Cloud template requires you to provide a shell script that fully implements your application
deployment and cleanup using the [`gcloud` CLI](https://cloud.google.com/sdk/gcloud) and all other tools available in the selected Docker image.

The deployment script is searched as follows:

1. look for a specific `gcp-deploy-$environment_type.sh` in the `$GCP_SCRIPTS_DIR` directory in your project (e.g. `gcp-deploy-staging.sh` for staging environment),
2. if not found: look for a default `gcp-deploy.sh` in the `$GCP_SCRIPTS_DIR` directory in your project,
3. if not found: the deployment job will fail.

The cleanup script is searched as follows:

1. look for a specific `gcp-cleanup-$environment_type.sh` in the `$GCP_SCRIPTS_DIR` directory in your project (e.g. `gcp-cleanup-staging.sh` for staging environment),
2. if not found: look for a default `gcp-cleanup.sh` in the `$GCP_SCRIPTS_DIR` directory in your project,
3. if not found: the cleanup job will fail.

> :information_source: 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 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`)
>     * `${hostname}`: the environment hostname, extracted from the current environment url (after late variable expansion - see below)
> 2. any [GitLab CI variable](https://docs.gitlab.com/ee/ci/variables/predefined_variables.html)
> 3. any [custom variable](https://docs.gitlab.com/ee/ci/variables/#add-a-cicd-variable-to-a-project)
>     (ex: `${SECRET_TOKEN}` that you have set in your project CI/CD variables)

### Environments URL management

The GCP 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):

* `$GCP_ENVIRONMENT_URL` to define a default url pattern for all your envs,
* `$GCP_REVIEW_ENVIRONMENT_URL`, `$GCP_INTEG_ENVIRONMENT_URL`, `$GCP_STAGING_ENVIRONMENT_URL` and `$GCP_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:
>   GCP_BASE_APP_NAME: "wonderapp"
>   # global url for all environments
>   GCP_ENVIRONMENT_URL: "https://%{environment_name}.nonprod.acme.domain"
>   # override for prod (late expansion of $GCP_BASE_APP_NAME not needed here)
>   GCP_PROD_ENVIRONMENT_URL: "https://$GCP_BASE_APP_NAME.acme.domain"
>   # override for review (using separate resource paths)
>   GCP_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).

You may also add and propagate your own custom variables, by pushing them to the `gcloud.env` file in your [deployment script](#deployment-and-cleanup-scripts).

## 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 Google Cloud template uses some global configuration used throughout all jobs.

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `GCP_CLI_IMAGE`          | the Docker image used to run Google Cloud CLI commands| `gcr.io/google.com/cloudsdktool/cloud-sdk:latest` |
| :lock: `GCP_KEY_FILE`    | Default [Service Account key file](https://cloud.google.com/bigquery/docs/authentication/service-account-file) | _none_ |
| `GCP_BASE_APP_NAME`      | Base application name                  | `$CI_PROJECT_NAME` ([see GitLab doc](https://docs.gitlab.com/ee/ci/variables/predefined_variables.html)) |
| `GCP_ENVIRONMENT_URL`    | Default environments url _(only define for static environment URLs declaration)_<br/>_supports late variable expansion (ex: `https://%{environment_name}.gcloud.acme.com`)_ | _none_ |
| `GCP_SCRIPTS_DIR`        | Directory where Google Cloud scripts (deploy & cleanup) are located | `.` _(root project dir)_ |

### 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 `GCP_REVIEW_PROJECT` variable (see below).

Here are variables supported to configure review environments:

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `GCP_REVIEW_PROJECT`     | Google Cloud project ID for `review` env | _none_ (disabled) |
| :lock: `GCP_REVIEW_KEY_FILE`| [Service Account key file](https://cloud.google.com/bigquery/docs/authentication/service-account-file) to authenticate on `review` env  _(only define if different from default)_    | `$GCP_KEY_FILE` |
| `GCP_REVIEW_APP_NAME`    | Application name for `review` env      | `"${GCP_BASE_APP_NAME}-${CI_ENVIRONMENT_SLUG}"` (ex: `myproject-review-fix-bug-12`) |
| `GCP_REVIEW_ENVIRONMENT_URL`| The review environments url _(only define for static environment URLs declaration and if different from default)_ | `$GCP_ENVIRONMENT_URL` |
| `GCP_REVIEW_AUTOSTOP_DURATION`| The amount of time before GitLab will automatically stop `review` environments | `4 hours` |

### 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 `GCP_INTEG_PROJECT` variable (see below).

Here are variables supported to configure the integration environment:

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `GCP_INTEG_PROJECT`      | Google Cloud project ID for `integration` env | _none_ (disabled) |
| :lock: `GCP_INTEG_KEY_FILE`|[Service Account key file](https://cloud.google.com/bigquery/docs/authentication/service-account-file) to authenticate on `integration` env  _(only define if different from default)_    | `$GCP_KEY_FILE` |
| `GCP_INTEG_APP_NAME`     | Application name for `integration` env | `${GCP_BASE_APP_NAME}-integration` |
| `GCP_INTEG_ENVIRONMENT_URL`| The integration environment url _(only define for static environment URLs declaration and if different from default)_ | `$GCP_ENVIRONMENT_URL` |

### Staging environment configuration

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

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

Here are variables supported to configure the staging environment:

| Name                     | description                            | default value     |
| ------------------------ | -------------------------------------- | ----------------- |
| `GCP_STAGING_PROJECT`    | Google Cloud project ID for `staging` env | _none_ (disabled) |
| :lock: `GCP_STAGING_KEY_FILE`|[Service Account key file](https://cloud.google.com/bigquery/docs/authentication/service-account-file) to authenticate on `staging` env  _(only define if different from default)_    | `$GCP_KEY_FILE` |
| `GCP_STAGING_APP_NAME`   | Application name for `staging` env     | `${GCP_BASE_APP_NAME}-staging` |
| `GCP_STAGING_ENVIRONMENT_URL`| The staging environment url _(only define for static environment URLs declaration and if different from default)_ | `$GCP_ENVIRONMENT_URL` |

### Production environment configuration

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

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

Here are variables supported to configure the production environment:

| Name                      | description                            | default value     |
| ------------------------- | -------------------------------------- | ----------------- |
| `GCP_PROD_PROJECT`        | Google Cloud project ID for `production` env | _none_ (disabled) |
| :lock: `GCP_PROD_KEY_FILE`|[Service Account key file](https://cloud.google.com/bigquery/docs/authentication/service-account-file) to authenticate on `production` env  _(only define if different from default)_    | `$GCP_KEY_FILE` |
| `GCP_PROD_APP_NAME`       | Application name for `production` env  | `$GCP_BASE_APP_NAME` |
| `GCP_PROD_ENVIRONMENT_URL`| The production environment url _(only define for static environment URLs declaration and if different from default)_ | `$GCP_ENVIRONMENT_URL` |
| `GCP_PROD_DEPLOY_STRATEGY`| Defines the deployment to production strategy. One of `manual` (i.e. _one-click_) or `auto`. | `manual` |

## Examples

### Google AppEngine application

#### Context

Let's imagine a backend service:

* named **coockedoodledoo**,
* developped in whichever language,
* part of project named **farmvoices**
* hosted on Google AppEngine with project ID `farmvoices-12345`
* with review, staging and production environments enabled.

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

```yaml
include:
  # Include Google Cloud template
  - project: 'to-be-continuous/gcloud'
    ref: '4.1.0'
    file: '/templates/gitlab-ci-gcloud.yml'
  ...

# Global variables
variables:
  ...

  # Google Cloud
  # GCP_KEY_FILE defined as secret CI/CD variable
  GCP_REVIEW_PROJECT: "farm-12345" # enable review env
  GCP_STAGING_PROJECT: "farm-12345" # enable staging env
  GCP_PROD_PROJECT: "farm-12345" # enable production env
  GCP_STAGING_ENVIRONMENT_URL: "https://staging-dot-coockedoodledoo-dot-farmvoices-12345.ew.r.appspot.com"
  GCP_PROD_ENVIRONMENT_URL: "https://coockedoodledoo-dot-farmvoices-12345.ew.r.appspot.com"

  # Postman
  REVIEW_ENABLED: "true"

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

# define review environment url (uses $CI_ENVIRONMENT_SLUG as app version)
gcp-review:
  environment:
    url: "https://$CI_ENVIRONMENT_SLUG-dot-coockedoodledoo-dot-farmvoices-12345.ew.r.appspot.com"
```

#### AppEngine manifest

```yaml
# Google AppEngine manifest
# see: https://cloud.google.com/appengine/docs/standard/java11/config/appref
runtime: TODO # depends on languages
instance_class: F2
service: coockedoodledoo

...

variables:
  # this is an example of hardcoded (non-sensitive) configuration variable
  SOME_CONFIG: "some-value"
  # this is an example of variabilized (secret) configuration variable
  # will be replaced programmatically during deployment
  SOME_SECRET: "${SOME_SECRET}"
```

#### hook scripts

##### `gcp-deploy.sh`

This script is executed by the template to perform the application(s) deployment based on `gcloud` CLI. 

```bash
#!/usr/bin/env bash
echo "[gcp-deploy] Deploy burger/$CI_ENVIRONMENT_SLUG..."

# prepare GAE deployment directory (copy build output)
mkdir -p gae
cp build/* gae

# copy manifest with variables substitution
awk '{while(match($0,"[$]{[^}]*}")) {var=substr($0,RSTART+2,RLENGTH-3);gsub("[$]{"var"}",ENVIRON[var])}}1' < src/app.yaml > gae/app.yaml

# gcloud deploy
# use $CI_ENVIRONMENT_SLUG as the version
cd gae

if [[ "$CI_ENVIRONMENT_SLUG" == "production" ]]
then
  promote_opt="--promote"
else
  promote_opt="--no-promote"
fi

gcloud --quiet app deploy --project=${gcp_project_id} --version=${CI_ENVIRONMENT_SLUG} $promote_opt
```

##### `gcp-cleanup.sh`

This script is executed by the template to perform the application(s) cleanup based on `gcloud` CLI (review env only).

```bash
#!/usr/bin/env bash
echo "[gcp-cleanup] Cleanup burger/$CI_ENVIRONMENT_SLUG..."

# use $CI_ENVIRONMENT_SLUG as the version
gcloud --quiet app versions delete --project=${gcp_project_id} --service=coockedoodledoo ${CI_ENVIRONMENT_SLUG}
```

## Variants

The Google Cloud template can be used in conjunction with template variants to cover specific cases.

### OIDC variant

This variant enables [federated authentication using OpenID Connect](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/).

If you wish to use this authentication mode, please follow carefully [the GitLab guide](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/), then configure appropriately the related variables:

* `GPC_OIDC_PROVIDER` / `GPC_OIDC_ACCOUNT` for any global/common access,
* `GPC_<env>_OIDC_PROVIDER` / `GPC_<env>_OIDC_ACCOUNT` if you wish to use separate settings with any of your environments.

The `GPC_OIDC_PROVIDER` & `GPC_<env>_OIDC_PROVIDER` variable shall be of the form:

```
projects/<PROJECT_NUMBER>/locations/global/workloadIdentityPools/<POOL_ID>/providers/<PROVIDER_ID>
```

The following commands may help you retrieve the different values: 

- `gcloud projects describe $GCP_PROJECT --format="value(projectNumber)"` will return the `PROJECT_NUMBER` value
- `gcloud iam workload-identity-pools list  --location=global --format="value(name)"` will list you POOL_IDs available on your `GCP_PROJECT`
- `gcloud iam workload-identity-pools providers list --workload-identity-pool=<my-pool>  --location=global --format="value(name)"` will return the list of available `PROVIDER_ID` for one `POOL_ID`

#### Configuration

The variant supports the following configuration:

| Name              | description                            | default value     |
| ----------------- | -------------------------------------- | ----------------- |
| `GCP_OIDC_AUD`    | The `aud` claim for the JWT | `$CI_SERVER_URL` |
| `GCP_OIDC_PROVIDER`      | Default Workload Identity Provider associated with GitLab to [authenticate with OpenID Connect](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/) | _none_ |
| `GCP_OIDC_ACCOUNT`       | Default Service Account to which impersonate with OpenID Connect authentication | _none_ |
| `GCP_REVIEW_OIDC_PROVIDER` | Workload Identity Provider associated with GitLab to [authenticate with OpenID Connect](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/) on `review` environment | _none_ |
| `GCP_REVIEW_OIDC_ACCOUNT`  | Service Account to which impersonate with OpenID Connect authentication on `review` environment | _none_ |
| `GCP_INTEG_OIDC_PROVIDER` | Workload Identity Provider associated with GitLab to [authenticate with OpenID Connect](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/) on `integration` environment | _none_ |
| `GCP_INTEG_OIDC_ACCOUNT`  | Service Account to which impersonate with OpenID Connect authentication on `integration` environment | _none_ |
| `GCP_STAGING_OIDC_PROVIDER` | Workload Identity Provider associated with GitLab to [authenticate with OpenID Connect](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/) on `staging` environment | _none_ |
| `GCP_STAGING_OIDC_ACCOUNT`  | Service Account to which impersonate with OpenID Connect authentication on `staging` environment | _none_ |
| `GCP_PROD_OIDC_PROVIDER` | Workload Identity Provider associated with GitLab to [authenticate with OpenID Connect](https://docs.gitlab.com/ee/ci/cloud_services/google_cloud/) on `production ` environment | _none_ |
| `GCP_PROD_OIDC_ACCOUNT`  | Service Account to which impersonate with OpenID Connect authentication on `production ` environment | _none_ |

#### Example

```yaml
include:
  # main template
  - project: 'to-be-continuous/gcloud'
    ref: '4.1.0'
    file: '/templates/gitlab-ci-gcloud.yml'
  # Vault variant
  - project: 'to-be-continuous/gcloud'
    ref: '4.1.0'
    file: '/templates/gitlab-ci-gcloud-oidc.yml'

variables:
  # audience claim for JWT
  GCP_OIDC_AUD: "https://iam.googleapis.com"
  # common OIDC config for non-prod envs
  GCP_OIDC_PROVIDER: "projects/<gcp_nonprod_proj_id>/locations/global/workloadIdentityPools/<pool_id>/providers/<provider_id>"
  GCP_OIDC_ACCOUNT: "<name>@$<gcp_nonprod_proj_id>.iam.gserviceaccount.com"
  # specific OIDC config for prod
  GCP_PROD_OIDC_PROVIDER: "projects/<gcp_prod_proj_id>/locations/global/workloadIdentityPools/<pool_id>/providers/<provider_id>"
  GCP_PROD_OIDC_ACCOUNT: "<name>@$<gcp_prod_proj_id>.iam.gserviceaccount.com"
```

### 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/gcloud'
    ref: '4.1.0'
    file: '/templates/gitlab-ci-gcloud.yml'
  # Vault variant
  - project: 'to-be-continuous/gcloud'
    ref: '4.1.0'
    file: '/templates/gitlab-ci-gcloud-vault.yml'

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

# enable VAULT_JWT_TOKEN ID token for GCP jobs only
.gcp-base:
  id_tokens:
    VAULT_JWT_TOKEN:
      # use your own audience url here
      aud: https://gitlab.com
```