How to execute some task in background within a docker container - docker

Question

I'm trying to perform some user operation(change admin-user), after Neo4j container boots up. But my background script doesn't wait for the neo4j to come up and dies before Neo4j comes online.
entrypoint.sh is something like
if [some condition]
my_function &
fi
if [${cmd}" == "neo4j" ]; then
exec neo4j console
fi
helper_file.sh has my_function
function my_function {
echo "Checking to see if Neo4j has started at http://${DB_HOST}:${DB_PORT}..."
curl --retry-connrefused --retry 5 --retry-max-time 300 http://${DB_HOST}:${DB_PORT}
if [ $? -ne 0 ]; then
echo "Curl failed with error $?. Exiting.."
return 1
fi
migrate_users <--- another function
}
the problem that I'm facing is Neo4j doesn't bootup till curl is doing the retries.
Tue Sep 20 12:46:35 UTC 2022 Checking to see if Neo4j has started at http://localhost:7474...
Tue Sep 20 12:46:35 UTC 2022 % Total % Received % Xferd Average Speed Time Time Time Current
Tue Sep 20 12:46:35 UTC 2022 Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
Tue Sep 20 12:46:35 UTC 2022 curl: (7) Failed to connect to localhost port 7474: Connection refused
Tue Sep 20 12:46:35 UTC 2022 Curl failed with error 0. Exiting..
user: vmanage; command: neo4j
Directories in use:
How can I ensure that migrate_users function gets called after Neo4j has come up online completely?
Edit:
thank you for providing the suggestion.
If I go with the background process approach, I'm seeing that Neo4j doesn't boots up, till curl queries have finished
Tue Sep 20 18:57:34 UTC 2022 Checking to see if Neo4j has started
at http://localhost:7474...
Tue Sep 20 18:57:34 UTC 2022 Neo4j not ready
Tue Sep 20 18:57:34 UTC 2022 Connection refused
Tue Sep 20 18:57:34 UTC 2022 config-db is not up, try to setup password again
user: vmanage; command: neo4j
Directories in use:
home: /var/lib/neo4j
config: /var/lib/neo4j/conf
logs: /log
plugins: /var/lib/neo4j/plugins
import: /var/lib/neo4j
data: /data
certificates: /var/lib/neo4j/certificates
licenses: /var/lib/neo4j/licenses
run: /var/lib/neo4j/run
Starting Neo4j.
Going to try this : https://github.com/neo4j/docker-neo4j/issues/166#issuecomment-486890785

Answer 1

You can add a loop inside your script to check the health of neo4j container. If the health check get pass only proceeed further in you script otherwise loop untill it pass.

Answer 2

You can use docker-compose with the depends_on + condition to do that.
Even docker-compose documentation recommends to implement some kind of script to wait until the service is up. Take a look to the following links docker-compose and stackoverflow
But it could be something like:
version: "2"
services:
neo4j-admin:
build: .
depends_on:
- "neo4j"
command: ["./wait-for-it.sh","--", "sh", "change_admin_passwd.sh"]
neo4j:
image: neo4j

Answer 3

Your function named my_function could use until to keep waiting for neo4j to start, for example:
function my_function {
let RETRIES=0
declare SUCCESS=0
until [[ $SUCCESS -eq 1 ]] || [[ $RETRIES -eq 50 ]]; do
echo "Checking to see if Neo4j has started at
http://${DB_HOST}:${DB_PORT}..."
STATUS_CODE=$(curl -w %{http_code} -o /dev/null -s http://${DB_HOST}:${DB_PORT})
if [[ $STATUS_CODE -eq 200 ]]; then
echo "Neo4j is up and running" && SUCCESS=1 && exit 0
else
echo "Neo4j not ready" && let RETRIES+=1 && sleep 10
fi
done
migrate_users
}