Populate cassandra after Docker-compose finishes - docker

Question

Here's my docker-compose.yaml:
version: '3'
services:
cassandra:
container_name: cassandra
image: cassandra:3.10
ports:
- 9142:9042
volumes:
- $PWD/src/database/migrations:/migrations
depends_on:
- mysql
mysql:
image: mysql:5.7
volumes:
- ./src/database/migrations:/docker-entrypoint-initdb.d
ports:
- 3307:3306
restart: always
environment:
- MYSQL_ROOT_PASSWORD=password
- MYSQL_DATABASE=leonardo
- MYSQL_ALLOW_EMPTY_PASSWORD=1
And a shell script bootstrap.sh to start:
#!/bin/bash
set -e
docker-compose -f $PWD/docker-compose.yaml down
docker-compose -f $PWD/docker-compose.yaml up -d
This is working and fires up the stack.
Now I'd like to add a keyspace to Cassandra, however, below this line throws an error:
docker-compose -f $PWD/docker-compose.yaml exec cassandra /bin/sh -c $'cqlsh cassandra -e "CREATE KEYSPACE mykeyspace WITH replication = {\'class\': \'SimpleStrategy\', \'replication_factor\': \'1\'} AND durable_writes = true;"'
Connection error: ('Unable to connect to any servers', {'172.18.0.2':
error(111, "Tried connecting to [('172.18.0.2', 9042)]. Last error:
Connection refused")})
Cassandra has probably not initialised yet.
What's a good approach for this?

Answer 1

If you try to execute a command in Cassandra in your bootstrap.sh script just after starting the containers, the Cassandra server won't have the time to start.
A simple solution would be to wait a few seconds in your script before executing the command, using an until loop:
#!/bin/bash
set -e
docker-compose -f $PWD/docker-compose.yaml down
docker-compose -f $PWD/docker-compose.yaml up -d
until docker-compose -f $PWD/docker-compose.yaml exec cassandra /bin/sh -c "cqlsh cassandra -e 'show version'";
do
docker-compose -f $PWD/docker-compose.yaml exec cassandra /bin/sh -c $'cqlsh cassandra -e "CREATE KEYSPACE mykeyspace WITH replication = {\'class\': \'SimpleStrategy\', \'replication_factor\': \'1\'} AND durable_writes = true;"'
done