Merge pull request 'docs(downloads): new page for release assets and download verification' (#10) from docs/release-download-verification into main

Reviewed-on: #10

docs/dci-deploysas9.md

@@ -14,6 +14,8 @@ There are two ways to deploy Data Controller on SAS 9:
 * Full Deployment (preferred)
 * Streaming (for quick demos)
 
+Both fetch a deployment program from the [releases page](https://git.datacontroller.io/dc/dc/releases) - see the [downloads page](/downloads) for what each asset contains and how to verify it.
+
 ### Full Deployment
 
 #### 1 - Deploy Stored Processes
@@ -27,7 +29,7 @@ filename dc url "https://git.datacontroller.io/dc/dc/releases/download/latest/sa
 %inc dc;
 ```
 
-If you don't have internet access from SAS, download `sas9.sas` from [here](https://git.datacontroller.io/dc/dc/releases), and change the initial `compiled_apploc` and `compiled_serverName` macro variable assignments as necessary.
+If you don't have internet access from SAS, download `sas9.sas` from [here](https://git.datacontroller.io/dc/dc/releases), verify it against the release `SHA256SUMS` file ([downloads page](/downloads/#verifying-a-download)), and change the initial `compiled_apploc` and `compiled_serverName` macro variable assignments as necessary.
 
 #### 2 - Deploy the Frontend
 
@@ -35,7 +37,7 @@ The Data Controller frontend comes pre-built, and ready to deploy to the SAS Web
 
 Deploy as follows:
 
-1.  Download the `frontend.zip` file from: [https://git.datacontroller.io/dc/dc/releases](https://git.datacontroller.io/dc/dc/releases)
+1.  Download the `frontend.zip` file from: [https://git.datacontroller.io/dc/dc/releases](https://git.datacontroller.io/dc/dc/releases) (verify it against the release `SHA256SUMS` file - see the [downloads page](/downloads/#verifying-a-download))
 2. Create a folder for Data Controller in the [htdocs folder of your SAS Web Server](https://sasjs.io/frontend-deployment/#sas9-deploy) - typically a subdirectory of: `!SASCONFIG/LevX/Web/WebServer/htdocs` - and unzip the archive **into** that folder. The archive holds the frontend files at its root, so `index.html` sits directly inside your folder (alongside the `images` folder and the compiled asset files) - for example `htdocs/dc/index.html`.
 3. Open the `index.html` file and update the values in the `<sasjs>` tag as follows:
 
@@ -93,7 +95,7 @@ filename dc url "https://git.datacontroller.io/dc/dc/releases/download/vX.X.X/de
 %inc dc;
 ```
 
-If you don't have internet access from your SAS environment, just download `demostream_sas9.sas` from [https://git.datacontroller.io/dc/dc/releases](https://git.datacontroller.io/dc/dc/releases) and modify the `appLoc` on line 2, as follows:
+If you don't have internet access from SAS, download `demostream_sas9.sas` from [https://git.datacontroller.io/dc/dc/releases](https://git.datacontroller.io/dc/dc/releases) (verify it against the release `SHA256SUMS` file - see the [downloads page](/downloads/#verifying-a-download)) and modify the `appLoc` on line 2, as follows:
 
 ![](img/sas9_apploc.png)
 

docs/downloads.md

@@ -0,0 +1,52 @@
+---
+layout: article
+title: DC Downloads
+description: Data Controller release assets and how to verify them
+---
+
+# Downloads
+
+Data Controller releases are published on the [releases page](https://git.datacontroller.io/dc/dc/releases) of the source repository. Every release carries the same set of assets:
+
+| Asset | Use |
+|---|---|
+| `frontend.zip` | The pre-built web frontend, for deployments that serve the frontend from a web server (SAS 9 full deploy, Viya separated deploy) |
+| `sas9.sas` | SAS 9 full deployment program (stored processes + frontend registration) |
+| `demostream_sas9.sas` | SAS 9 streaming deployment program (demos and evaluations) |
+| `viya.sas` | Viya streaming deployment program (backend + frontend) |
+| `viya_noweb.sas` | Viya separated deployment program (backend only) |
+| `viya_noweb.json` | The Viya backend services as a SASjs Drive JSON deployment bundle |
+| `sasjs_server.json.zip` | SASjs Server deployment bundle (all services, for [SASjs Server](https://server.sasjs.io) deployments) |
+| `SHA256SUMS` | SHA-256 checksums for every asset above |
+
+Which asset you need depends on the deployment route - see [SAS 9 Deployment](/dci-deploysas9) or [SAS Viya Deployment](/deploy-viya).
+
+## Verifying a download
+
+Every asset is covered by the `SHA256SUMS` file, which the release pipeline generates over the exact files it uploads. To verify a download:
+
+1. Download the asset (for example `frontend.zip`) from the [releases page](https://git.datacontroller.io/dc/dc/releases).
+2. Download `SHA256SUMS` from the same release into the same folder.
+3. Run the check:
+
+```bash
+sha256sum --check SHA256SUMS --ignore-missing
+```
+
+Each asset that matches reports `OK`. The `--ignore-missing` flag means you only need the files you actually downloaded - the check skips assets you did not fetch.
+
+On Windows, `certutil` can compute the hash of a single file for comparison against the value listed in `SHA256SUMS`:
+
+```
+certutil -hashfile frontend.zip SHA256
+```
+
+### What the checksum proves
+
+A matching checksum confirms the asset is byte-for-byte the file the release pipeline uploaded. It catches corrupted and tampered downloads - interrupted transfers, proxies or mirrors that altered the file in transit.
+
+It is not a cryptographic signature. The hashes travel in the same release as the files they cover, so they protect the download path, not the release itself: a compromise of the forge would allow both the asset and its checksum to be altered together. For download integrity - the typical concern when fetching deployment artifacts over the internet - it is the standard check.
+
+## Integrity inside SAS
+
+The SAS deployment programs embed the frontend and services as generated SAS code. Once `%inc`'d, their integrity is established by the check above at download time. They deploy the stored processes or jobs into the SAS Folder you nominate (`appLoc`) - a metadata location, not physical disk - and the only physical location they write to is the Data Controller location (`dcLoc`) you configure. The programs can be [reviewed in full](https://code.datacontroller.io) (or in the [source repository](https://git.datacontroller.io/dc/dc)) before you run them.

mkdocs.yml

@@ -71,6 +71,7 @@ nav:
 - Macros: macros.md
 - Installation:
     - System Requirements: dci-requirements.md
+    - Downloads: downloads.md
     - SAS Viya: deploy-viya.md
     - SAS 9 EBI: dci-deploysas9.md
     - SAS 9 STP Hardening: dci-stpinstance.md