Dot env file is not found in docker compose file

Background

So there is a case I need to substitue the variables defined in .env to the docker compose for further process, but when I run the docker-compose up command, the variable refer in docker compose file cannot be interpreted.  

Reason

Normally the .env file sits to the same directory as the docker compose yml file, and is expected the docker compose command being executed in the current directory of the docker compose file and the .env file, which I am not in this case.

Solutions

If the current directory is not the place where the compose file is sitting in, we need to specify --project-directory to allow docker-compose program to be able to recognize the directory where the yml file and the .env file sits in, the correct command after fixing is as follows

docker-compose -f {docker-compose-file-dir} --project-directory={directory-of-docker-compose-file} up -d

Setting up custom variables in gitlab pipeline

Background

Having a new pipeline needed to setup, I try to put some frequently use variables e.g. AWS login ID to the custom variable convenient for my pipeline usage, but somehow it fails to read the variable 

Reason

Settings problem, I configure the variable as a protected variable, which only allows protected branches or tags to use only, as the target branch is not configured, the custom variable is not recognized

Solutions

We need to configure our target branch as a protected branch in Settings > Repository > Protected Tags, in that section we can input regular expression for the tags identified as "protected" branch, after that, the custom variable is recognized successfully

Unable to deploy webpage through docker of AWS lightsail instance

Background

So I am trying to build and deploy a very simple LAMP application through docker, but encounters difficulties of repeatedly restarting mySQL server with the following errors

mysqld entered running state exit status 0 expected

It repeatedly restarts and never stops until I turn off the docker services. I am annoying on this because deploying a LAMP based web site through docker should be short and shouldn't take too much time.

Reason

So I finally figure out I can investigate through mySQL log through /var/log/mariadb/mariadb.log, you can determine the exact log path in the my.cnf file located in /etc/my.cnf

And this shows up as 1 of the log

innodb: cannot allocate memory for the buffer pool

Bingo ! So memory insufficient is the cause

Solutions

As I am using AWS Lightsail, the cheapest plan with only 512mb ram, and the remaining RAM is just several MBs, which is totally not enough for running all 2 containers (lamp docker container & ftp).

The I quickly think of swap spaces, which use fast SSD as memory, following URL's guidance, the LAMP docker service can be run successfully 

References

• How To Add Swap on Ubuntu 14.04
• Mysql cannot allocate memory for the buffer pool
• How do I allocate memory to work as swap space in an Amazon EC2 instance by using a swap file?
• Amazon Linux 2 - install docker and docker-compose
• How to increase swap space?