feat: add utility script to upgrade docker-snap version (#199)

* add: utility script to upgrade docker-snap version

- It works by running it from the base root of the project:
```
./.github/workflows/upgrade.sh
```
It generates the necessary changes on snap/snapcraft.yaml
by fetching the latest version available for Moby
using the GitHub api.
And then based on the Dockerfile for the latest version, it
fetches the necessary tags for the other parts of docker-snap.
It only changes the needed code and not the comments.

* feat: use GitHub releases API
* feat: fetch only the last release of the api consult
* feat: add helper functions
 * helper to check if yq is present.
 * helper to check the need of update.
 * replace all occurencies of the old engine version
    for the new one in the comments.

Signed-off-by: Lincoln Wallace <[email protected]>

---------

Signed-off-by: Lincoln Wallace <[email protected]>

upgrade.sh

@@ -0,0 +1,119 @@
+#!/bin/bash
+
+set -eux
+
+fetch_latest() {
+  # Fetch latest version from Github releases API
+  LATEST=$(curl -s "https://api.github.com/repos/moby/moby/releases?per_page=1" | jq -r '.[0].tag_name')
+}
+
+# Validate the version format
+validate_version() {
+  # Original simplified RegEx:
+  # v\d+.\d+.\d+\-*(rc.\d|rc\d|beta.\d)*
+  # By analysing the last tags on github.com/moby/moby/tags
+  # of last 3 years (since 2021).
+  if [[ "$LATEST" =~ ^v[0-9]+\.[0-9]+\.[0-9]+(-rc\.[0-9]|rc[0-9]|beta\.[0-9])?$ ]]; then
+    echo "$LATEST matches the regex."
+  else
+    echo "Version doesn't match known pattern."
+    exit 1
+  fi
+}
+
+check_yq() {
+  if ! command -v yq &>/dev/null; then
+    echo -e "yq is not installed."
+    echo -e "Please run:"
+    echo -e "\tsudo snap install yq"
+    exit 1
+  fi
+}
+
+check_new_version() {
+  if [[ "$CURRENT" == "$LATEST" ]]; then
+    echo -e "Docker snap is already updated\n"
+    exit 0
+  fi
+}
+
+main() {
+  check_yq
+
+  # Define the path to the YAML file
+  yaml_file="snap/snapcraft.yaml"
+
+  CURRENT=$(yq e '.parts.engine.source-tag' "$yaml_file")
+
+  fetch_latest
+
+  echo "Latest TAG: $LATEST"
+
+  validate_version
+
+  check_new_version
+
+  SNAP_VERSION=${LATEST#v}
+  echo -e "New snap version $SNAP_VERSION"
+
+  echo "The latest version of moby is: $LATEST"
+
+  # Fetch the Dockerfile
+  dockerfile=$(curl -s "https://raw.githubusercontent.com/moby/moby/refs/tags/$LATEST/Dockerfile")
+
+  # Declare variables and their corresponding regex patterns
+  declare -A variables=(
+    [GO_VERSION]='^ARG GO_VERSION='
+    [CONTAINERD_VERSION]='^ARG CONTAINERD_VERSION='
+    [RUNC_VERSION]='^ARG RUNC_VERSION='
+    [TINI_VERSION]='^ARG TINI_VERSION='
+    [DOCKERCLI_VERSION]='^ARG DOCKERCLI_VERSION='
+    [BUILDX_VERSION]='^ARG BUILDX_VERSION='
+    [COMPOSE_VERSION]='^ARG COMPOSE_VERSION='
+  )
+
+  # Extract versions using a loop
+  for var in "${!variables[@]}"; do
+    value=$(echo "$dockerfile" | awk -F= "/${variables[$var]}/ {print \$2}")
+
+    # Handle special cases: GO_VERSION and BUILDX_VERSION
+    if [[ "$var" == "GO_VERSION" ]]; then
+      # for GO_VERSION Extract major.minor
+      value=$(echo "$value" | awk -F. '{print $1 "." $2}')
+    elif [[ "$var" == "BUILDX_VERSION" && $value != v* ]]; then
+      value="v$value" # Prepend 'v' if missing
+    fi
+
+    declare "$var=$value"
+    echo "$var: ${!var}"
+  done
+
+  # Replace the `version:` field with the value of $SNAP_VERSION
+  yq -i ".version = \"$SNAP_VERSION\"" "$yaml_file"
+
+  # Replace fields in YAML using a loop
+  declare -A yaml_updates=(
+    [engine.source-tag]=$LATEST
+    [containerd.source-tag]=$CONTAINERD_VERSION
+    [runc.source-tag]=$RUNC_VERSION
+    [tini.source-tag]=$TINI_VERSION
+    [docker-cli.source-tag]=$DOCKERCLI_VERSION
+    [buildx.source-tag]=$BUILDX_VERSION
+    [compose-v2.source-tag]=$COMPOSE_VERSION
+  )
+
+  for part in "${!yaml_updates[@]}"; do
+    yq -i ".parts.${part} = \"${yaml_updates[$part]}\"" "$yaml_file"
+  done
+
+  # Replace `build-snaps` for `engine` with $GO_VERSION
+  yq -i '.parts.engine."build-snaps"[0] |= sub("[0-9]+\.[0-9]+", "'"$GO_VERSION"'")' "$yaml_file"
+
+  # Replace the remaining comments
+  sed -i "s/$CURRENT/$LATEST/g" "$yaml_file"
+
+  echo "YAML file updated successfully."
+
+}
+
+main