catch errors when scraping datadir from help output

Author: yosifkit

5.5/docker-entrypoint.sh

@@ -19,7 +19,17 @@ for arg; do
 done
 
 _datadir() {
-	"$@" --verbose --help --log-bin-index=`mktemp -u` 2>/dev/null | awk '$1 == "datadir" { print $2; exit }'
+	toRun=( "$@" --verbose --help --log-bin-index="$(mktemp -u)" )
+	if ! "${toRun[@]}" 2>/tmp/mysql-config-error.log | awk '$1 == "datadir" { print $2; exit }'; then
+		cat >&2 - /tmp/mysql-config-error.log <<-EOM
+
+			ERROR: mysqld failed while attempting to determine datadir
+			command was: "${toRun[*]}"
+
+		EOM
+		exit 1
+	fi
+	rm /tmp/mysql-config-error.log
 }
 
 # allow the container to be started with `--user`

5.6/docker-entrypoint.sh

@@ -19,7 +19,17 @@ for arg; do
 done
 
 _datadir() {
-	"$@" --verbose --help --log-bin-index=`mktemp -u` 2>/dev/null | awk '$1 == "datadir" { print $2; exit }'
+	toRun=( "$@" --verbose --help --log-bin-index="$(mktemp -u)" )
+	if ! "${toRun[@]}" 2>/tmp/mysql-config-error.log | awk '$1 == "datadir" { print $2; exit }'; then
+		cat >&2 - /tmp/mysql-config-error.log <<-EOM
+
+			ERROR: mysqld failed while attempting to determine datadir
+			command was: "${toRun[*]}"
+
+		EOM
+		exit 1
+	fi
+	rm /tmp/mysql-config-error.log
 }
 
 # allow the container to be started with `--user`

5.7/docker-entrypoint.sh

@@ -19,7 +19,17 @@ for arg; do
 done
 
 _datadir() {
-	"$@" --verbose --help 2>/dev/null | awk '$1 == "datadir" { print $2; exit }'
+	toRun=( "$@" --verbose --help )
+	if ! "${toRun[@]}" 2>/tmp/mysql-config-error.log | awk '$1 == "datadir" { print $2; exit }'; then
+		cat >&2 - /tmp/mysql-config-error.log <<-EOM
+
+			ERROR: mysqld failed while attempting to determine datadir
+			command was: "${toRun[*]}"
+
+		EOM
+		exit 1
+	fi
+	rm /tmp/mysql-config-error.log
 }
 
 # allow the container to be started with `--user`