feat: allow users to run custom commands before exit

Dockerfile

@@ -1,6 +1,6 @@
 FROM node:20-alpine
 
-RUN apk add --no-cache jq=1.7.1-r0 && \
+RUN apk add --no-cache jq=1.7.1-r0 curl=8.8.0-r0 && \
 	npm install -g wikibase-cli@17.0.8
 
 COPY --chmod=755 ./transferbot.sh /usr/bin/transferbot

README.md

@@ -6,6 +6,7 @@ A Docker image providing a command that transfers entities from a source to a ta
 
 ```
 docker run --rm ghcr.io/wbstack/transferbot \
+	-e CALLBACK_ON_SUCCESS="echo 'this worked'" -e CALLBACK_ON_FAILURE="echo 'this failed'" \
 	https://source.wikibase.cloud https://target.wikibase.cloud Q1 P1 Q2
 ```
 
@@ -36,6 +37,18 @@ The OAuth access token used for authenticating against the target wiki.
 
 The OAuth access secret used for authenticating against the target wiki.
 
+## Running commands after the script has finished
+
+It's possible to provide commands that should be run when the script has finished.
+
+### `CALLBACK_ON_SUCCESS` (optional)
+
+If a value is set for this key, its content will be executed in case the script exits 0.
+
+### `CALLBACK_ON_FAILURE` (optional)
+
+If a value is set for this key, its content will be executed in case the script exits non-zero.
+
 ---
 
 This work is distributed under the [BSD 3-Clause license](./LICENSE).

transferbot.sh

@@ -3,6 +3,17 @@
 set -eu
 set -o pipefail
 
+trap finish EXIT INT TERM
+
+finish () {
+  exit_code=$?;
+  if [ ! -z "${CALLBACK_ON_SUCCESS:-}" ] && [ "$exit_code" = 0 ]; then
+    sh -c "$CALLBACK_ON_SUCCESS"
+  elif [ ! -z "${CALLBACK_ON_FAILURE:-}" ] && [ "$exit_code" != 0 ]; then
+    sh -c "$CALLBACK_ON_FAILURE"
+  fi
+}
+
 source_wiki_origin="$1"
 shift
 target_wiki_origin="$1"