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How to add a specific IP to your RDS security group on command line

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If you go towards DevOps, automated provisioning, you definetely will need to do things in automation.


Here is the command line, in case you need the new automated provisioned server to be added in your RDS security group:

aws rds rds-authorize-db-security-group-ingress –db-security-group-name mydbsecuritygroup –cidrip

How to block an IP on AWS?

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Security Groups on AWS by default blocks all, so you can just define what you allow. As a result, you cannot block an IP using Security Group, e.g. to prevent a specific IP to access to your web port

ACL is right there for that need. You need to define the IP/IPs which you want to block and remember to keep the rule 100 always in place:)


AWS Elasticbeanstalk NewRelic agent installation

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Credits for @umitunal_

    newrelic-sysmond: []
      command: nrsysmond-config –set license_key=xxxxxxxxxxxxxx
      command: echo hostname=NameOfYourServer >> /etc/newrelic/nrsysmond.cfg
      command: /etc/init.d/newrelic-sysmond start

AWS SSL Certificate cannot be added

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Although the private and public keys are valid (Already tested on another platform), AWS Web Console is giving error while i am trying to define under ELB Listeners.

In order to debug the situtation, the following command line will be helpful:

aws iam upload-server-certificate –server-certificate-name my-server-cert –certificate-body file://my-certificate.pem –private-key file://my-private-key.pem –certificate-chain file://my-certificate-chain.pem –debug

AWS instance metadata

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Just a simple best-practice for you to know in case you need to get instance related data during automation:


For example, if you want to use the hostname in your automation, just use the output:

$ curl

WordPress and CloudFront Access-Control-Allow-Origin problem a.k.a. CORS

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You may be having the following type of error after you enable CDN on your WordPress:

Font from origin '' has been blocked from loading by Cross-Origin Resource Sharing policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '' is therefore not allowed access.

That's because you do not have the "Access-Control-Allow-Origin" header set by the web-server of the origin, which is Apache or Amazon S3.

You can verify this with the following command and you will not see the header:

curl -I -s -X GET -H "Origin:"

1- With S3: In order to set that header in S3, refer to the AWS Documentation.

2- Without S3: 

2-a: CloudFront:

– Edit Behaviors

– Change "Allowed HTTP Methods" to GET, HEAD, OPTIONS, PUT, POST, PATCH, DELETE

– Change "Forward Forward" headers to "Whitelist"

– Add "origin" to Whitelist headers

2-b: Apache

You need to You just need the following to be added under the Document section in your httpd.conf:

Header set Access-Control-Allow-Origin "*"

and gracefuly restart your http server:

apachectl -k graceful

Check if the header appeared with the "curl" command previously we used.


HTTP/1.0 200 OK

Content-Type: image/png

Content-Length: 299245

Date: Wed, 16 Dec 2015 22:28:00 GMT

Server: Apache

X-Frame-Options: SAMEORIGIN

Last-Modified: Wed, 09 Dec 2015 15:07:22 GMT

ETag: "490ed-52678727d1480"

Accept-Ranges: bytes

Access-Control-Allow-Origin: *

X-Cache: Miss from cloudfront

X-Amz-Cf-Id: e14A-xV0D-ajm0S7wLe696YombjT8zKCmbr0LL8NmqlMarArJo1jnw==

X-Cache: MISS from

X-Cache-Lookup: MISS from

Via: 1.1 (CloudFront), 1.0 (squid/3.1.23)

Connection: keep-alive

Building Microservices

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I have recently finished reading Sam Newman's "Building Microservices" book, from which i learned so many topics that were questions in my mind towards building micro services.

Micro Services

Although there are so many lessons i learned, but the most remarkable ones are:

– Services are communicated between each other on service-level rather than via DB

– Although there is no restriction, but having seperate DB for each/set of services is ok

– Service orchestration and scaling

– Breaking monolith into pieces




git repository from scratch

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I just need to bring up a git repo from scratch and push to github on a computer where there was initially

– NO git repo

– NO ssh keys to connect to github


So here are the straightforward steps:

1. Initializing git repo on the directory where you want:

git init

2. Adding all the files to the git repository:

git add .

3. First commit:

git commit -m "First commit"

4. Adding a remote repository:

git remote add origin [email protected]/funkydorian/ansible.git

5. You can check the effect of the previous step by:

cat .git/config

6. Check if you have ssh keys in order to connect to github:

ls ~/.ssh/id_rsa

7. If yes, check if you can connect to github:

ssh -T [email protected]

7. If not, create the keys:

ssh-keygen -t rsa -b 4096 -C "[email protected]"

8. Add your private key identities to the authentication agent:

ssh-add ~/.ssh/

9. Copy the key to your clipboard:

pbcopy < ~/..ssh/

10. Login to your from your browser

Settings –> SSH Keys –> Add Key –> Paste the content of

11. Create the repository on

12. Check again if you can connect to github:

ssh -T [email protected]

You must see the output like:

"You've successfully authenticated…."

13. Try to push to github:

git push -v origin master DevOps Presentation

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The images are from today's DevOps presentation


n11 DevOps 20151026_173203

Docker –link

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I was trying to find a use-case of the "–link" functionality in Docker in terms of a "Service Discovery" perspective and i found the following repo:

Seems some way through… I will be going deeper, any comments are appreciated….


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