Mail Basics — about MX records, A records, TXT records etc

CF. MainEnable Setup
Prerequisites >>
- install software on a Master Server
- Need A record of mail.Master Server
- Need MX record of mail.Master Server
- IIS needs to route traffic to the Master Server (for web console client)

Attaching EFS to Rocket Chat or MongoDB instance
1. Beware of the Security groups
2. Install yum install nfs-utils (to mount via nfs)
- you can mount via nfs, efs helper(DNS), or by IP
3. execute command mount -t nfs4 -o XXXXX:/ /where/you/want/to/mount(inlocal)
- to unmount umount /where/you/mounted/on/local

  • * You…

First Create Active Directory in AWS
- (type in like a domain name)
- 2 Availability zones

Create Master Server EC2

  • add this computer to the domain !
    ( System Properties > Computer Name Domain > Add the domain)
    - If cannot find domain -> need to add the…

  • How to check ports running (used ports)
    netstat -ab
  • Cp command
    copy DIRECTORY/filename DIRECTORY/tofilename
  • View file (=cat)
    type <filename>
  • Set environment variable (export $XXX)
    for /f %i in (<command>, output) do setx RELEASE_VERSION=%i /M
  • 2 commands at once
    - IF you want to run it tgt (without sequence)
    : <command> & <command>
    - IF you want to run it with sequence (Dependency)
    : <command> && <command>
  • How to redirect/configure IP tables
    : netsh advfirewall firewall add rule name=”HTTPS port” dir=in action=allow protocol=TCP localport=443
    : netsh interface portproxy add v4tov4 listenport=443 connectport=8080 connectaddress=
  • In resource (EC2), you should provide securitygroupID, instead of actual securitygroup name → or will throw parameter group error
  • If you launch AMI with Windows, the administrator password will be the same + also you will not be able to retrieve a new windows password
  • AWS::CloudFormation::WaitCondition is to WAIT until the configuration stpes are done — before announcing the EC2 creation complete !
    Must use together with WaitConditionHandler
  • If you use custom AMI image, User data will not probably be execued, since it’s already started
  • Every command in the “init:config” section, will wait for 60 seconds to reboot if not specified “waitAfterCompletion: 0”

AWS Secrets Manager
→ create the key — could be RDS, DynamoDB, or custom
→ Put in any <key> <value> pair

How to access :
1. via program code ex. require(aws)
2. via CLI command line
this will output a JSON format of file

  • Prerequisite
    - aws configure (login to…

Cache vs Artifacts

  • Cache are globally defined
    if you cache .m2/respository → all the later stages/jobs will have that repo by default
  • Artifacts are defined within a “stage”
    if you make .m2/repository …

Standard process
git status
git add .
git commit -m “new change”
git push [repository name]

How to push to branch
git status
lets you check which branch you’re on
git branch OR git branch --list
git branch june
git checkout june

How to pull ONLY a branch repo
git clone -b june <repo url>

If there is no “REMOTE” repository but have “local” repository
will get error that there is no upstream branch
git push --set-upstream origin[repositoryname] june

How to check origin (=remote branch)
git remote -v
git remote set-url origin new.git.url/here

When your instance failes to create
— Because they failed to create specific resources (security group, route53)
— Because the success health check signal didn’t come through for a certain time → This doesn’t give you much info about error
(Mostly because of Metadata(cfn-init) or UserData)

Then How should we Troubleshoot?
* Turn Off the “roll back function
- So we can go into the instance to troubleshoot
→ ‘Stack Creation Option’ : Rollback — disable (When launching template)

Then SSH into instance and Check — Metadata, Userdata, etc
* /var/log/cfn-init.log
* Check User Data Script : cat /var/lib/cloud/instance/scripts/part-001

June Chung

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