Add HEALTHCHECK directive

This commit adds HEALTHCHECK instructions to the Dockerfiles.

The actual healthcheck logic is in the `healthcheck.sh` file, which is
copied into the image via a `COPY` instruction in the Dockerfiles. The
reason for the separate script vs. inline in the Dockerfile is that
AFAIK, environment replacement isn't supported by the `HEALTCHECK`
instruction.

Author: hyleung

5.5/Dockerfile

@@ -71,7 +71,12 @@ RUN mkdir -p /var/lib/mysql /var/run/mysqld \
 VOLUME /var/lib/mysql
 
 COPY docker-entrypoint.sh /usr/local/bin/
+COPY healthcheck.sh /usr/local/bin/
+
 RUN ln -s usr/local/bin/docker-entrypoint.sh /entrypoint.sh # backwards compat
+
+HEALTHCHECK CMD ["/bin/bash", "/usr/local/bin/healthcheck.sh"]
+
 ENTRYPOINT ["docker-entrypoint.sh"]
 
 EXPOSE 3306

5.5/healthcheck.sh

@@ -0,0 +1,3 @@
+#/bin/bash
+
+mysql --protocol=socket -hlocalhost -uroot -p$MYSQL_ROOT_PASSWORD -e 'SELECT 1'

5.6/Dockerfile

@@ -57,7 +57,12 @@ RUN sed -Ei 's/^(bind-address|log)/#&/' /etc/mysql/my.cnf \
 VOLUME /var/lib/mysql
 
 COPY docker-entrypoint.sh /usr/local/bin/
+COPY healthcheck.sh /usr/local/bin/
+
 RUN ln -s usr/local/bin/docker-entrypoint.sh /entrypoint.sh # backwards compat
+
+HEALTHCHECK CMD ["/bin/bash", "/usr/local/bin/healthcheck.sh"]
+
 ENTRYPOINT ["docker-entrypoint.sh"]
 
 EXPOSE 3306

5.6/healthcheck.sh

@@ -0,0 +1,3 @@
+#/bin/bash
+
+mysql --protocol=socket -hlocalhost -uroot -p$MYSQL_ROOT_PASSWORD -e 'SELECT 1'

5.7/Dockerfile

@@ -57,7 +57,12 @@ RUN sed -Ei 's/^(bind-address|log)/#&/' /etc/mysql/mysql.conf.d/mysqld.cnf \
 VOLUME /var/lib/mysql
 
 COPY docker-entrypoint.sh /usr/local/bin/
+COPY healthcheck.sh /usr/local/bin/
+
 RUN ln -s usr/local/bin/docker-entrypoint.sh /entrypoint.sh # backwards compat
+
+HEALTHCHECK CMD ["/bin/bash", "/usr/local/bin/healthcheck.sh"]
+
 ENTRYPOINT ["docker-entrypoint.sh"]
 
 EXPOSE 3306

5.7/healthcheck.sh

@@ -0,0 +1,3 @@
+#/bin/bash
+
+mysql --protocol=socket -hlocalhost -uroot -p$MYSQL_ROOT_PASSWORD -e 'SELECT 1'

8.0/Dockerfile

@@ -57,7 +57,12 @@ RUN sed -Ei 's/^(bind-address|log)/#&/' /etc/mysql/mysql.conf.d/mysqld.cnf \
 VOLUME /var/lib/mysql
 
 COPY docker-entrypoint.sh /usr/local/bin/
+COPY healthcheck.sh /usr/local/bin/
+
 RUN ln -s usr/local/bin/docker-entrypoint.sh /entrypoint.sh # backwards compat
+
+HEALTHCHECK CMD ["/bin/bash", "/usr/local/bin/healthcheck.sh"]
+
 ENTRYPOINT ["docker-entrypoint.sh"]
 
 EXPOSE 3306

8.0/healthcheck.sh

@@ -0,0 +1,3 @@
+#/bin/bash
+
+mysql --protocol=socket -hlocalhost -uroot -p$MYSQL_ROOT_PASSWORD -e 'SELECT 1'