为什么这会有什么不同？ 搬运工/ MySQL的/ apache2的

Question

i can barley explain whats happening but check it out... i am using Docker over here with mysql, php, apache2.

it makes a difference if i start everything up at once like this:

docker-compose up mysql apache2

or if i decide to first start only mysql in a terminal window like this:

docker-compose up mysql

and in a seperate terminal window apache2:

docker-compose up apache2

if i start up all at once it happens many many times that i end up with following error:

Missing Tablespace

sometimes it helps to just use

docker-compose down

followed by another

docker-compose up mysql apache2

but most of the time the error is consistent. i can avoid this error all the time with starting the systems in seperate windows, first mysql - once its fired up i start apache2.

how can this be a thing? i dont have enough docker knowledge to understand this kind of issue, but i would like to. in my opinion apache should not talk to mysql until the actual application gets hit by a request?

any advice is much appreciated - let me know if further information is needed

Answer 1

There is option in docker-compse.yaml, called depends_on to define the requirement order to start your services:

version: '3.4'
services:
  mysql:
    image: mysql:5.6
  apache2:
    image: httpd:alpine
    depends_on:
      - mysql

Then, you should use docker-compose up to start both.

Reference: https://docs.docker.com/compose/compose-file/#depends_on