feat: devcontainer part 4 (#3339)

add utils.sh, prelim docs

Signed-off-by: Dave Lee <dave@gray101.com>

.devcontainer-scripts/utils.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+
+# This file contains some really simple functions that are useful when building up customization scripts.
+
+
+# Checks if the git config has a user registered - and sets it up if not.
+#
+# Param 1: name
+# Param 2: email
+#
+config_user() {
+    local gcn=$(git config --global user.name)
+    if [ -z "${gcn}" ]; then
+        echo "Setting up git user / remote"
+        git config --global user.name "$1"
+        git config --global user.email "$2"
+        
+    fi
+}
+
+# Checks if the git remote is configured - and sets it up if not. Fetches either way.
+#
+# Param 1: remote name
+# Param 2: remote url
+#
+config_remote() {
+    local gr=$(git remote -v | grep $1)
+    if [ -z "${gr}" ]; then
+        git remote add $1 $2
+    fi
+    git fetch $1
+}
+
+# Setup special .ssh files
+#
+# Param 1: bash array, filenames relative to the customization directory that should be copied to ~/.ssh
+setup_ssh() {
+    local files=("$@")
+    for file in "${files[@]}"; then
+        local cfile="/devcontainer-customization/${file}"
+        local hfile="~/.ssh/${file}"
+        if [ ! -f "${hfile}" ]; then
+            echo "copying ${file}"
+            cp "${cfile}" "${hfile}"
+            chmod 600 "${hfile}"
+        fi
+    done
+    ls ~/.ssh
+}

.devcontainer/customization/README.md

@@ -7,14 +7,19 @@ If files with those names exist here, they will be called at the end of the norm
 
 This is a good place to set things like `git config --global user.name` are set - and to handle any other files that are mounted via this directory.
 
-An example of a useful script might be:
+To assist in doing so, `source /.devcontainer-scripts/utils.sh` will provide utility functions that may be useful - for example:
 
 ```
 #!/bin/bash
-gcn=$(git config --global user.name)
-if [ -z "$gcn" ]; then
-    git config --global user.name YOUR.NAME
-    git config --global user.email YOUR.EMAIL
-    git remote add PREFIX FORK_URL
-fi
+
+source "/.devcontainer-scripts/utils.sh"
+
+sshfiles=("config", "key.pub")
+
+setup_ssh "${sshfiles[@]}"
+
+config_user "YOUR NAME" "YOUR EMAIL"
+
+config_remote "REMOTE NAME" "REMOTE URL"
+
 ```