Merge branch 'secure-files-feature-docs' into 'master'

Adding Project-level Secure Files feature documentation

See merge request gitlab-org/gitlab!85213

doc/ci/secure_files/index.md

+---
+stage: Verify
+group: Pipeline Authoring
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
+type: reference
+---
+
+# Project-level Secure Files **(FREE)**
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/78227) in GitLab 14.8. [Deployed behind the `ci_secure_files` flag](../../administration/feature_flags.md), disabled by default.
+
+FLAG:
+On self-managed GitLab, by default this feature is not available. To make it available,
+ask an administrator to [enable the feature flag](../../administration/feature_flags.md)
+named `ci_secure_files`. Limited to 100 secure files per project. Files must be smaller
+than 5 MB. The feature is not ready for production use.
+
+You can securely store files for use in CI/CD pipelines as "secure files". These files
+are stored securely outside of your project's repository, and are not version controlled.
+It is safe to store sensitive information in these files. Secure files support both
+plain text and binary file types.
+
+Secure files can be [downloaded and used by CI/CD jobs](#use-secure-files-in-cicd-jobs)
+by using the [load-secure-files](https://gitlab.com/gitlab-org/incubation-engineering/devops-for-mobile-apps/load-secure-files)
+tool.
+
+NOTE:
+This feature is in active development and is likely to change, potentially in a breaking way.
+Additional features and capabilities are planned.
+
+## Add a secure file to a project
+
+To add a secure file to a project, use the [Secure Files API](../../api/secure_files.md#create-secure-file).
+
+Send a POST request to the secure files endpoint for your project:
+
+```shell
+curl --request POST --header "PRIVATE-TOKEN: <your_access_token>" \
+     "https://gitlab.example.com/api/v4/projects/:project_id/secure_files" --form "name=myfile.jks" --form "file=@/path/to/file/myfile.jks"
+```
+
+The response returns all of the metadata for the file you just uploaded. For example:
+
+```json
+{
+    "id": 1,
+    "name": "myfile.jks",
+    "checksum": "16630b189ab34b2e3504f4758e1054d2e478deda510b2b08cc0ef38d12e80aac",
+    "checksum_algorithm": "sha256",
+    "permissions": "read_only",
+    "created_at": "2022-02-22T22:22:22.222Z"
+}
+```
+
+## List all secure files in a project
+
+To list all secure files in a project, use the [Secure Files API](../../api/secure_files.md#list-project-secure-files).
+
+Send a GET request to the secure files endpoint for your project:
+
+```shell
+curl --request GET --header "PRIVATE-TOKEN: <your_access_token>" \
+     "https://gitlab.example.com/api/v4/projects/:project_id/secure_files"
+```
+
+The response returns an array of all of the secure files in the project. For example:
+
+```json
+[{
+    "id": 1,
+    "name": "myfile.jks",
+    "checksum": "16630b189ab34b2e3504f4758e1054d2e478deda510b2b08cc0ef38d12e80aac",
+    "checksum_algorithm": "sha256",
+    "permissions": "read_only",
+    "created_at": "2022-02-22T22:22:22.222Z"
+}]
+```
+
+## Use secure files in CI/CD jobs
+
+To use your secure files in a CI/CD job, you must use the [`load-secure-files`](https://gitlab.com/gitlab-org/incubation-engineering/devops-for-mobile-apps/load-secure-files)
+tool to download the files in the job. After they are downloaded, you can use them
+with your other script commands.
+
+Add a command in the `script` section of your job to download the `load-secure-files` tool
+and execute it. The files download into a `.secure_files` directory in the root of the project.
+To change the download location for the secure files, set the path in the `SECURE_FILES_DOWNLOAD_PATH`
+[CI/CD variable](../variables/index.md).
+
+For example:
+
+```yaml
+test:
+  variables:
+    SECURE_FILES_DOWNLOAD_PATH: './where/files/should/go/'
+  script:
+    - curl --silent "https://gitlab.com/gitlab-org/incubation-engineering/devops-for-mobile-apps/load-secure-files/-/raw/main/installer" | bash
+```