Generate release changelog based on commits

scripts/generate_changelog.sh

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+#
+# This script obtains the changelog to be introduced in the new release.
+
+set -eu
+
+function log_error() {
+    echo "Error:" "$@" >&2
+    exit 1
+}
+
+function log_info() {
+    echo -e "[+]" "$@"
+}
+
+GIT_BIN=$(which git) || log_error 'git is not installed. Please follow https://github.com/git-guides/install-git for instructions'
+
+# Generate the changelog between the provided tag and origin/master.
+function generate_changelog() {
+    local tag="$1"
+    # From the remote origin url, get a link to pull requests.
+    remote_link=$($GIT_BIN config --get remote.origin.url | sed 's/\.git/\/pull\//g') || log_error 'Failed to get remote origin url'
+
+    prs=$($GIT_BIN --no-pager log --pretty=format:"%s" "$tag"..origin/master) || log_error 'Failed to obtain commit list'
+
+    log_info "Changelog\n"
+    while IFS= read -r line; do
+        # Obtain the pr number from each line. The regex should match, as provided by the previous grep.
+        if [[ $line =~ "(#"([0-9]+)")"$ ]]; then
+            pr_number="${BASH_REMATCH[1]}"
+        else
+            continue
+        fi
+
+        # Generate a valid PR link.
+        pr_link="$remote_link$pr_number"
+        # Generate the link as markdown.
+        pr_md_link=" ([#$pr_number]($pr_link))"
+        # Print the changelog line as `- commit-title pr-link`.
+        echo "$line" | awk -v var="$pr_md_link" '{NF--; printf "- "; printf; print var}'
+    done <<< "$prs"
+}
+
+# Get latest release tag.
+tag=$($GIT_BIN describe --match "v[0-9]*" --abbrev=0 origin/master) || log_error 'Failed to obtain the latest release tag'
+log_info "Latest release tag: $tag"
+# TODO: verify that the tag is part of an actual release
+$GIT_BIN verify-tag "$tag" > /dev/null 2>&1 || log_error 'Failed to verify tag'
+
+generate_changelog "$tag"