Add markup file for hld command (#513)

Author: edaena

docs/commands/data.json

@@ -236,7 +236,8 @@
   "hld append-variable-group": {
     "command": "append-variable-group <variable-group-name>",
     "alias": "avg",
-    "description": "Appends the name of an existing variable group to the current manifest-generation.yaml file."
+    "description": "Appends the name of an existing variable group to the current manifest-generation.yaml file.",
+    "markdown": "## Description\n\nAppend a variable group name to the current `manifest-generation.yaml` of an\ninitialized hld repository.\n\n## Example\n\nWhen an HLD repository is first initialized with `spk hld init`, the top portion\nof the `manifest-generation.yaml` looks like this:\n\n```yaml\n# GENERATED WITH SPK VERSION 0.5.8\ntrigger:\n  branches:\n    include:\n      - master\nvariables: []\npool:\n  vmImage: ubuntu-latest\nsteps:\n.\n.\n.\n```\n\nrunning `spk hld append-variable-group my-vg` with a variable group name, in\nthis case `my-vg`, will add it under the `variables` section if it does not\nalready exist:\n\n```yaml\n# GENERATED WITH SPK VERSION 0.5.8\ntrigger:\n  branches:\n    include:\n      - master\nvariables:\n  - group: my-variable-group\npool:\n  vmImage: ubuntu-latest\nsteps:\n.\n.\n.\n```\n"
   },
   "hld init": {
     "command": "init",

src/commands/hld/append-variable-group.md

@@ -0,0 +1,44 @@
+## Description
+
+Append a variable group name to the current `manifest-generation.yaml` of an
+initialized hld repository.
+
+## Example
+
+When an HLD repository is first initialized with `spk hld init`, the top portion
+of the `manifest-generation.yaml` looks like this:
+
+```yaml
+# GENERATED WITH SPK VERSION 0.5.8
+trigger:
+  branches:
+    include:
+      - master
+variables: []
+pool:
+  vmImage: ubuntu-latest
+steps:
+.
+.
+.
+```
+
+running `spk hld append-variable-group my-vg` with a variable group name, in
+this case `my-vg`, will add it under the `variables` section if it does not
+already exist:
+
+```yaml
+# GENERATED WITH SPK VERSION 0.5.8
+trigger:
+  branches:
+    include:
+      - master
+variables:
+  - group: my-variable-group
+pool:
+  vmImage: ubuntu-latest
+steps:
+.
+.
+.
+```

src/lib/fileutils.ts

@@ -496,11 +496,23 @@ export const appendVariableGroupToPipelineYaml = (
       path.join(dir, fileName)
     ) as AzurePipelinesYaml;
     pipelineFile.variables = pipelineFile.variables || [];
+    let variableGroupExists = false;
+
+    pipelineFile.variables.forEach((variable) => {
+      if ("group" in variable && variable.group === variableGroupName) {
+        variableGroupExists = true;
+        logger.info(
+          `Variable group '${variableGroupName}' already exits in '${dir}/${fileName}'.`
+        );
+      }
+    });
 
-    pipelineFile.variables.push({ group: variableGroupName });
+    if (!variableGroupExists) {
+      pipelineFile.variables.push({ group: variableGroupName });
 
-    logger.info(`Updating '${dir}/${fileName}'.`);
-    write(pipelineFile, dir, fileName);
+      logger.info(`Updating '${dir}/${fileName}'.`);
+      write(pipelineFile, dir, fileName);
+    }
   } catch (err) {
     throw buildError(
       errorStatusCode.FILE_IO_ERR,