feat: Support multiple configuration files (#389)

* Allow configuration to be distributed

* catch iteration errors when collecting config files

* rm unused func

* Fix suffix check for config loading

* test configuration loading

* GATUS_CONFIG_PATH can be a file or a directory now

* Add deprecation note

* Fix cs

Co-authored-by: TwiN <twin@linux.com>

* cs fixes

Co-authored-by: TwiN <twin@linux.com>

* cs fixes

Co-authored-by: TwiN <twin@linux.com>

* cs fixes

Co-authored-by: TwiN <twin@linux.com>

* cs + rm useless line

Co-authored-by: TwiN <twin@linux.com>

* Update config/config.go

Co-authored-by: TwiN <twin@linux.com>

test-conf/conf.d/endpoints.yaml

@@ -0,0 +1,24 @@
+endpoints:
+  - name: front-end
+    group: core
+    url: "https://twin.sh/health"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+      - "[BODY].status == UP"
+      - "[RESPONSE_TIME] < 150"
+
+  - name: back-end
+    group: core
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+      - "[CERTIFICATE_EXPIRATION] > 48h"
+
+  - name: monitoring
+    group: internal
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"

test-conf/conf.d/endpoints.yml

@@ -0,0 +1,29 @@
+endpoints:
+  - name: nas
+    group: internal
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+
+  - name: example-dns-query
+    url: "8.8.8.8" # Address of the DNS server to use
+    interval: 5m
+    dns:
+      query-name: "example.com"
+      query-type: "A"
+    conditions:
+      - "[BODY] == 93.184.216.34"
+      - "[DNS_RCODE] == NOERROR"
+
+  - name: icmp-ping
+    url: "icmp://example.org"
+    interval: 1m
+    conditions:
+      - "[CONNECTED] == true"
+
+  - name: check-domain-expiration
+    url: "https://example.org/"
+    interval: 1h
+    conditions:
+      - "[DOMAIN_EXPIRATION] > 720h"

test-conf/config.yaml

@@ -0,0 +1,6 @@
+endpoints:
+  - name: example
+    url: https://example.org
+    interval: 30s
+    conditions:
+      - "[STATUS] == 200"