• [CHANGE] Telegram Integration: api_url is now optional. #2981
• [CHANGE] Telegram Integration: ParseMode default is now HTML instead of MarkdownV2. #2981
• [CHANGE] Webhook Integration: url is now marked as a secret. It will no longer show up in the logs as clear-text. #3228
• [CHANGE] Metrics: New label reason for alertmanager_notifications_failed_total metric to indicate the type of error of the alert delivery. #3094 #3307
• [FEATURE] Clustering: New flag --cluster.label, to help to block any traffic that is not meant for the cluster. #3354
• [FEATURE] Integrations: Add Microsoft Teams as a supported integration. #3324
• [ENHANCEMENT] Telegram Integration: Support bot_token_file for loading this secret from a file. #3226
• [ENHANCEMENT] Webhook Integration: Support url_file for loading this secret from a file. #3223
• [ENHANCEMENT] Webhook Integration: Leading and trailing white space is now removed for the contents of url_file. #3363
• [ENHANCEMENT] Pushover Integration: Support options device and sound (sound was previously supported but undocumented). #3318
• [ENHANCEMENT] Pushover Integration: Support user_key_file and token_file for loading this secret from a file. #3200
• [ENHANCEMENT] Slack Integration: Support errors wrapped in successful (HTTP status code 200) responses. #3121
• [ENHANCEMENT] API: Add CORS and Cache-Control HTTP headers to all version 2 API routes. #3195
• [ENHANCEMENT] UI: Receiver name is now visible as part of the alerts page. #3289
• [ENHANCEMENT] Templating: Better default text when using {{ .Annotations }} and {{ .Labels }}. #3256
• [ENHANCEMENT] Templating: Introduced a new function trimSpace which removes leading and trailing white spaces. #3223
• [ENHANCEMENT] CLI: amtool silence query now supports the --id flag to query an individual silence. #3241
• [ENHANCEMENT] Metrics: Introduced alertmanager_nflog_maintenance_total and alertmanager_nflog_maintenance_errors_total to monitor maintenance of the notification log. #3286
• [ENHANCEMENT] Metrics: Introduced alertmanager_silences_maintenance_total and alertmanager_silences_maintenance_errors_total to monitor maintenance of silences. #3285
• [ENHANCEMENT] Logging: Log GroupKey and alerts on alert delivery when using debug mode. #3438
• [BUGFIX] Configuration: Empty list of receivers and inhibit_rules would cause the alertmanager to crash. #3209
• [BUGFIX] Templating: Fixed a race condition when using the title function. It is now race-safe. #3278
• [BUGFIX] API: Fixed duplicate receiver names in the api/v2/receivers API endpoint. #3338
• [BUGFIX] API: Attempting to delete a silence now returns the correct status code, 404 instead of 500. #3352
• [BUGFIX] Clustering: Fixes a panic when tls_client_config is empty. #3443
• [BUGFIX] Fix stored XSS via the /api/v1/alerts endpoint in the Alertmanager UI.